FACTORS ASSOCIATED WITH BREAKDOWN OF

by

Raymond Laurent Granger

A thesis submitted to the Faculty of Graduate Studies and Research of McGill University in partial fulfilment of the requirements for the degree of Doctor of Philosophy

Department of Plant Science, Macdonald College of McGill University, c Montreal• March, 1979 iii - •

I dedicate this thesis

to my wife

UIREILLE ABSTRACT

FACTORS ASSOCIATED HITH SPARTAN BREAKDOWN OF APPLE

DEPARTMENT OF PLANT SCIENCE

RAYMOND LAURENT GRANGER

Quebec-grown Spartan were compared with those from British

Columbia in an effort to explain why B.C. fruits are more susceptible

to the Spartan breakdown storage disorder. Based on fruit diameter

apples were sized into small, medium and lar~e categories from Quebec

and medium, large and extra large from British Columbia. Peel and

flesh tissues of individual apples from each category were analysed

for total N, P, K, Ca, Mg and Zn. Firmness, percent red colour, specific

gravity, moisture content, titrateable acidity and percent soluble

solids along with and release rates also were determined on co2 c2n4 individual fruits in every category.

Large fruit size, decreasin~ firmness and high or H release co2 c2 4 rates expressed on a fruit basis were associated with Spartan breakdown

development in cold storage. The predictive values of the various

mineral analyses for Spartan breakdown were in the following order:

peel Mg > flesh K > flesh P > flesh Mg > flesh Ca > peel K > peel Ca.

The British Columbia apples contained significantly higher levels

of all elements except those of N and Ca which were not significantly

different in the fruit from both pr.ovinces. c i In a second experiment the clonal apple rootstocks M 26, M 7,

MM 106 and MM 111 grafted to 'Spartan' and 'Delicious' were planted in pots of sand. After a period of growth the trees were depotted, pruned to the 3 basal leaves of the scion and the roots were immersed in a nutrient solution containing 45Ca. Gibberellic acid plus 6-Benzyladenine applied at the axillary buds of these leaves failed to promote their growth and interfered with 45Ca uptake. 'Spartan' trees took up more 45Ca than the 'Delicious' trees in the same time period. M 26, MM 106 and M 7 showed no signi­ ficant difference in their ability to transport 45Ca to the scion cultivar. However, al~ were significantly more efficient than MM 111.

ii 0 ABREGE FACTEURS ASSOCIES AU BRUNISSEMENT DE LA POMME SPARTAN DEPARTEMENT DE PHYTOTECHNIE RAYMOND LAURENT GRANGER

Un premier essai eut pour objet d'expliquer la moins grande sus­ ceptibilite au brunissement des pommes Spartan cultivees au Quebec comparativement a celles cultivees en Colombie Britannique. Des le debut on classa lea pommes du Quebec en petites, moyennes et grosses. Comparativement, celles de la Colombie Britannique furent classees en moyennes, grosses et tres grosses selon leur calibre. La pelure et la chair de fruits individuals de chaque categorie subirent une analyse en elements totaux de N, P, K, Ca, Mg et Zn. Chez ces memes

fruits on evalua en outre la fermete, le pourcentage de coloration rouge, la gravite specifique, la teneur en eau, en acidite titrable et en solublea solides. En plus on mesura lea taux de respiration et de degagement d'ethylene d'echantillons de pommea preleveea dans chaque categorie.

Le brunisaement de la pomme Spartan en entrepot refrigere s'aaso­ cia au fort calibre du fruit, a sa fermete ainai que son degagement de C0 ou de exprime sous une base de fruit. Lea elements qui 2 c2n4 ae aont averes lea meilleurs predicteurs du brunisaement furent, par ordre de priorite, la teneur en Mg de la pelure > en K de la chair > en P de la chair > en Mg de la chair > en Ca de la chair > en K de

la pelure > en Ca de la pelure. 0 Les pommes de la eolombie Britannique se sont revelees plus riches en tous les elements excepte en N et en ea. Les pommes du Quebec ne furent pas significativement di(ferentes de celles de la eolombie Britannique quant a ces deux elements.

Dans un deuxieme essai les porte-greffes clones M 26, M 7, MM 106

et MM 111 plantes dans des pots de sable furent greffes avec les Spartan et Delicieuse Rouge. Apres une periode de croissance

on depota les arbres puis apres les avoir rabattus au niveau de la troisieme feuille basale du scion on en immergea le systeme radiculaire

dans une solution nutritive contenant du calcium radioactif.

L'acide gibberellique ainsi que la 6-Benzyladenine lorsqu'appliques

sur les bourgeons axillaires de ces feuilles reduisirent la croissance des nouvelles tiges et diminuerent !'absorption du - 5ea. Le cultivar Spartan favorisa beaucoup plus !'absorption du ' 5ea que le cultivar Delicieuse Rouge. Les porte-greffes M 26, KM 106 et M 7 ne furent

pas significativement differents entre eux quant au transport du ' 5ea dans la partie superieure de l'arbre. eependant ils furent signifi- / cativement plus efficaces que le MM 111.

c 0 ACKNOWLEDGEHENTS

I wish to thank wholeheartedly Hr. J.J. Jasmin, who on behalf of

the Canada Department of Agriculture, enabled me to pursue my Ph.D.

studies. My sincere gratitude is conveyed to professor C.D. Taper,

Chairman, Department of Horticulture at Macdonald College and director

of this thesis, for his criticisms and kind assistance. I am parti­

cularly endebted also to Dr. D.V. Fisher, director of the Agriculture

Canada Research Station at Summerland, B.C. He very generously

introduced me to his professional colleagues who shared their faci­

lities and enabled me to conduct the experiments described in this

thesis.

Very special thanks are directed to Dr. N.E. Looney, head of the

Pomology Section at the C.D.A. Research Station of Summerland, B.C.,

whose encouragement, inspiration, enthusiasm and continued energetic

support were of primordial importance. Appreciation is extended to

Drs. S.W. Porritt, M. Meheriuk and Miss L. Berard C.D.A. post-harvest

physiologists at Summerland and St-Jean, whose vast experience was of

/great assistance to me. Similarly I wish to thank Dr. M. Faust of

the U.S.D.A. Fruit Research Laboratory at Beltsville, Md, U.S.A. for

his valuable advice.

For guidance in statistics I wish to express my gratitude to

Professor Fanous of Macdonald College, to Dr. Gilles Rousselle of

Agriculture Canada at St-Jean, and to Professor G. Eaton, Plant·Science c iv 0 Department, University of British Columbia. For the statistical analysis of the data, the assistance of Mr. D. Royer, Mr. C. Mcintosh

and Mr. K. Price respectively from Rt-Jean, Summerland and Ottawa

was greatly appreciated.

Advice and help in the laboratory by the late Mr. D. Riordan,

Mr. G. Wardle, Mr. B.G. Drought and Mr. J. MacDougal from Summerland

along with that of Mr. Y. Perron from St-Jean is gratefully acknow­

ledged. The efficient technical assistance of Mr. H. Schmid,

Mr. B. Taylor, Mr. A. Fisher and Hiss A. l~ardle all from Summerland,

has helped m~ to successfully complete my experiments. I am grateful

to the photographers Mr. F. Dolezsar and Mr. L.G. Simard, respectively

from Summerland and St-Jean who have taken or processed the photographs

and to Mr. H.R. Jackson of the Biographic Unit at Ottawa for drawing

the figures included herein. Likewise I recognize the great help of Miss c. Rolland in typing this thesis.

Finally I wish to acknowledge the kind-willingness of Dr. and

Mrs. J.L. Mason for exchanging their job site and facilities with me

for one year. /

March, 1979

V c TABLE OF CONTENTS

Chapter Page

ACKNOWLEDGEMENTS •• ~ • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • i V

LIST OF TABLES ••••••••••••••••••••••••••••••••••• ~ ••••••••••

LIST OF FIGURES •••••••••.•••••••••••••••••••••••••••••••••••

1. INTRODUCTION .•••••••••••••••• ~ ••.••••••••• ~ •.•••.••.• :...... 1

2. REVIEW OF LITERATURE~.~ •• :.:~ •••••••• ~.: •• :: •• :...... 3

2.1. Cultural Factors Associated with Apple Storage Disorders. 3 2.1.1. Introduction...... 3 2.1.2. Scion/rootstock relationships...... 3

2.1.3. Irrigation, pruning and thinning...... 4 2.1.4. Soil management, soil type and mineral content...... 6

2.1.5. Growth regulator and fungicide sprays...... 8

2.1.6. Time of harvest and post-harvest treatments...... 9

2.2. Nutritional Factors Associated With Storage Disorders •••• 12

2.2.1. Prominent role of calcium •••••••••••••••••••••••••••• 12

2.2.2. Elements other than Ca associated with storage di- sorders •••••••••••••••••••• ~••••••••••••••••••••••••• 16 2.2.3. Cytological, physiological and environemental factors 25

3. EXPERIMENTS AND RESULTS••••••••••••••••••••••••••••••••••••••• 32 3.1. Some Differences Between Quebec (Fresniere} and British Columbia (Summerland) Spartan Apples ••••••••••••••••••••• 32

3.1.1. Physical properties and chemical constituents as they relate to Spartan breakdown •••••••••••••••••••••••••• 32

3.l.l.A. Materials and methods •••••••• ~••••••••••••••••••••• 32

3.1.1.B. Results ••• ~ ••••••••••••••• ~~ •• ~.~ •••••• ~ •••••••.••• 43 3.l.l.B.l. Development of breakdown and rots in cold storage 43

3.l.l.B.2. Fruit mineral content...... 44 TABLE OF CONTENTS (Continued)

Chapter Page

3.1.l.B.3. Fruit firmness at harvest and after storage and colour, specific gravity, and tissue moisture content at harvest •••••• ~ ••• ~ ••••••• ~ •• ~~ ••••• ~ •• 56

3.l.l.B.4. Juice acidity and soluble solids content ••••••••• 61

3.l.l.C. Discussion •••••.•••••••••••• ~.~ •••••••.••• ~· •••••••• 61

3.l.l.C.l. Development of breakdown and rots in cold storage 61

3.l.l.C.2. Fruit mineral content ••••••• ~•••••••••••••••••••• 65 3.l.l.C.3. Fruit firmness, colour, specific gravity and moisture content •••••••• ~ •••••••••••••••••••••••• 92

3.l.l.C.4. Juice acidity and soluble solids content ••••••••• 96

3.1.2. Comparison Between British Columbia and Quebec Spartan. Apples With Regard to Postharvest Respiration and Ethylene Production Rates •••••••••••••••••••••••••••• 98

3.1.2.A. Materials and methods •••••••••••••••••••••••••••••• 98

3.1.2.B. Results ••••••••••••••••••••••••••••.••••••••••••••• 101

3.1.2.B.l. Respiration' at 20 0 C of B.C. and Quebec Spartan apples removed from 1°C storage shortly after harvest •••••••••••••••••••••••••••••••••••••••••• 101 3.1.2.B.2. Ethylene production at 20 0 C •••••••••••••••••••••• 104

3.1.2.B.3. Some qualitative changes of Spartan apples held for 12 days at 20°c •••••••••••••••••••••••••••••• 105

3.1.2.C. Discussion •••••••••.••••••••••••••••••••••••••••••• 106

3.1.2.C.l. Respiration•••••••••••••••••••••••••••••••••••••• 112 3.1.2.C.2. Ethylene production •••••••••••••••••••••••••••••• 115

3.1.2.C.3. Some qualitative changes of Spartan apples held for 12 days at 20°C ••••••••••••••••• ~ •••••••••••••••• 118

3.2. Absorption of ~ 5Calcium by Apple Rootstockg and Scion Cultivars •••••••• ~ •• ~~: .•••••••• ~~ •••••••• ~~~ •• ~~ •••••••••• 122 TABLE OF CONTENTS (Continued)

Chapter Page

3.2.1. Absorption of 45Ca by two cultivars on four rootstocks •• ~.~~ ••• ~.~ ••••• ~~~~ ••• ~~ ••• ~~~ ••••••• ~ ••• 122

3.2.1.A. Materials and methods~ •• ~ •••• ~.~~~~~ •• ~ •••••••••••• 122

3.2.l.B. ResultS ••••• ~ •••••••••••••• ~~~ •••••••••••••••• ~ •••• 142

3.2.l.C. Discussion •• ~ •• ~~ •••••••••••••••••• ~ •••••••••• ~ •••• 154

3.2.2. Effect of GA and BA treatments on the absorption of radiocalcium •••••••• ~ •••• ~ •• ~ • • • • • • • • • • • • • • • • • • • • • • •.• 162

3.2.2.A. Materials and methods •••••••••••••••••••••••••••••• 162

3.2.2.B. Results ••••••••• ~~ ••••••••••••••••••••••••••••••••• 163

3.2.2.C. Discussion ••••••• ~ •••• ~ •••••••••••••••••••••••••••• 165

4. SUMMARY AND CONCLUSIONS ••••••••••••••••••••••••••••••••••••••• 167

5. CONTRIBUTIONS TO ORIGINAL KNOWLEDGE. • • • • • • • • • • • • • • • • • • • • • • • . • • 172

6. LITERATtJRE CITED ••••••••••••••••••••••••••••••••••••••••••••••

.APPEN'DIX TABLES •••• 4i •••••••••••••••••••••••••••••••••••••••••• LIST OF TABLES

Table 1. Size designation of apples used in the experiment:.~.... 34

Table 2. Dates when samples of each class of Spartan apples were

processed in the· laboratory. • • • • • • • • • • • • • • • • • • • • • • • • • • • 35

Table 3. Per cent breakdown and rotting of apples of various

average diameters from Quebec and B.C •.examined 8 1/2

months after harvest ••••••••••••••••••••••••••••••••••• 46

Table 4. Total nitrogen content (% dry weight) of peel and flesh

tissue of B.C. and Quebec Spartan apples ••••••••••••••• 49

Table 5. Idem/l~gnesium content (ppm dry weight) •••••••••••••••• 51

Table 6. Idem/Potassium content (%dry weight) •••••••••••••••••• 52 Table 7. Idem/Calcium content (ppm dry weight)...... 53

Table 8. Idem/Phosphorus content (ppm dry weight) ••••••••••••••• 54

Table 9. Idem/Zinc content (ppm dry weight) •••••••••••• ·••••••••• 55

Table 10. Firmness (kg) of Quebec and B.C. Spartan apples of

different sizes (a) within 3 weeks of harvest and {b) after 8 1/2 months in 1°C storage ••••• ~ •••••••••••• 58

Table 11. Average surface red colour (%) of the Quebec and B.C.

Spartan apples•••••••••••••••••••••••··~········••••••• 59 Table 12. Specific gravity and percent peel and flesh moisture

content.. . . . • . . . . • ...... • ...... • . • . . 60

Table 13. Juice acidity (% malic acid) and percent soluble

solids measured shortly after harvest •••••••••••••••••• 62

Table 14. Correlation values (r) relating at factors studied

and presented in matrix form ••••••••••••••• : ••••••• : ••• 68 LIST OF TABLES (Continued)

Table 15. Soil analysis report.-. ••••• : •••••••• :~.~~~.~.~.~: •• : ••• 69

Table 16. Nitrogen, calcium, magnesium, potassium and phosphorus

content of peel and flesh ••• : •••••• ~:::· •••••••••••••••• 78

Table 17. Ion ratio in peel and flesh tissues of Spartan apples of

various sizes from Quebec and B.c:~.~: ••••••••••••••••• 79

Table 18. Correlation values of the most important ion ratios and

Spartan breakdown •••••• ~ ••• ~~~ •••• : •••••••••••••••• ~ ••• 80

Table 19. Year 1974 soil temperature (°C) at a 20 cm depth in

Quebec and B.C. near the experimental orchards ••••••••• 86

Table 20. Average carbon dioxide and ethylene production rate

per unit weight (12 days at 20°C).: •••••••••••••••••••• 107

Table 21. Idem per apple.·~ . .•••. ~ ..••• ~ •.••.. ~ •...•••.. _.. . • • • • . . • . 108

Table 22. Firmness of fruits used for co and C2H production 2 4 studies (10 days 20°C) ••••••••••••••••••••••••••••••••• 109

Table 23. Idem for soluble solids content •••••••••••••••••••••••• 110

Table 24. Idem for titrateable acidity in the fruit juice •••••••• 111

Table 25. Flow chart for _·Block I ••••••••••••••••••••••••••••••••• 125

Table 26. Number of days during which ~ 5 Ca was absorbed by apple

trees in each block in 1975 •••••••••••••••••••••••••••• 126 Table 27. Determination of quenching by CHC1 ••••••••••••••••••••. 136. 3

Table 28. Recuperation of radiocalcium per tree •• ~ ••••••••••••••• 145

Table 29. Levels of significance between the radiocalcium uptake

and four treatments ••••••••••••••.•• ~~~~~-~.~~ ••••••••• 146 LIST OF TABLES (Continued)

Table 30. Total uptake of radiocalcium per tree for rootstocks,

45 ...... cultivars and Ca levels ••••••••••.•.••••••• ~··••••••• 147

Table 31. Uptake of the full nutrient solution per tree~ ••••• ~ ••• 148

Table 32. Levels of significance between the radiocalcium uptake

at five locations of the tree •••••••••••••••••••••••••• 149

Table 33. Effect of growth regulators on the development of the

young shoots ••• ~ ••• ~ ••.• ~~~ •••••••••••••••••••• ~ •••.••• 164 LIST OF FIGURES Page Fig. 1 Summerland-grown Spartan apples severely affected by

breakdown-~ . ; •••. ~ ~ •. ~ ~ ~ • ~ ••• ~ •• ~ ~ ~ ~ • ~ ~ .• ~ •.•. ~. . . • • • • • . • 2

Fig. 2 -Spartan apples from Fresniere (Quebec)

-Spartan apples transfered to wooden bushel boxes with a

perforated polyethylene liner •••••••••••••••••••••••••• 33

Fig. 3 Apparatus used to measure fruit specific gravity •••••••• 36

Fig. 4 -Hand driven apple peeler

-Each apple was sliced into 8 uniform sectors ••••••••••• 38

Fig. 5 The peel and the flesh prepared for freeze drying ••••••• 39

Fig. 6 -Flesh and peel samples being placed into a laboratory

freeze dryer

-Dry samples in polyethylene bags ••••••••••••••••••••••• 40

Fig. 7 Collecting and analyzing juice •••••••••••••••••••••••••• 41

Fig. 8 Spartan breakdown development after 8 1/2 months of

storage at 20 C and high relative humidity ••••••••••••••• 47

Fig. 9 Relationship between fruit weight and breakdown in

Spartan apples.••••••••••••••••••••••••••••••••••••••••• 48 Fig. 10 Firmness in kg within 3 weeks of harvest related to Spartan

breakdown after 8 1/2 months in storage ••••••••••••••••• 57

Fig. 11 Spartan breakdown after 8 1/2 months in storage as related

to peel and flesh magnesium ••••••••••••••••••••••••••••• 71

Fig. 12 idem as related to peel and flesh potassium ••••••••••••• 75

Fig. 13 idem, as related to peel and flesh calcium •••••••• ~ ••••• 76

Fig. 14 idem, as related to peel and flesh phosphorus •••• ~ •••••• 84 LIST OF FIGURES (Continued)

Fig. 15 Changes in the total ash, potassium, calcium and

phosphorus contents of apples during

the growing season on an absolute basis ••••••• ~.~ ••••••• 88,

Fig. 16 Respiration jars containing 5 apples ••••••••••• ~ •••••••• 102

Fig. 17 The Hewlett Packard gas chromatograph •••• ~ •••••••••••••• 103

Fig. 18 A.Spartan /MM. 111 on apple tree one month after grafting

B.General tree development

C.Tree before heading back

D.Display of the aerating system (pump, main duct,

micro-tubing, milk cartons) ••••••••••••••••••••••••••• 127

Fig. 19 A.Water imersion system for tree removal

B.Root system close-up

C.Air bubling in nutrient solution

D.Plant tissues weighting ••••••••••••••••••••••••••••••• 128

Fig. 20 Leaf area chart•••••••••••••••••••••••••••••••·••••••••• 129 Fig. 21 A.Shoot total length measurement

B.Display at trees headed back

·C.Tree out of a container ••••••••••••••••••••••••••••••• 130

Fig. 22 A.Harvest of young shoots

B.Chopping at old leaves

C.Taking a "high bark" sample

D.Area of a bark sample ••••••••••••••••••••••••••••••••• 132

Fig. 23. Diagram of an experimental tree.:~ •••••• ~ •••••••• ~ •••••• 134

Fig. 24 Energy spectra of radiocalcium and radiocarbon.~ •••••••• 135 c LIST OF FIGURES (Continued)

Fig. 25 Quench correction curve.:.: ••••••••••• ~:.:.:: ••••••••••• 139

Fig. 26 Distribution of radiocalcium throughout the tree •••••••• 150

Fig. 27 Distribution at two levels of radiocalcium throughout

the tree . ..•. ~ ..••....•.•.••.•...•...... •..... ~ ~ . . • • . • • 151

Fig. 28 Distribution of radiocalciuin within each rootstock •••••• 152

Fig. 29 Idem for cultivar and tissue •••••••••••••••••••••••••••• 153

Fig. 30 Differences between the cultivars in % of radiocalcium

within each t~ssue •••••••••••••••••••••••••••••••••••••• 156

c - 1 -

1. INTRODUCTION

The Spartan apple originated at Summerland~ British Columbia,

from a cross between Mcintosh and Newtown and was named in 1936.

It is a red Mclntosh-type apple of outstanding eating quality. It

is the third most important apple in the Okanagan Valley, B.C. where

it grows ta perfection. When grown under irrigated conditions (B.C.)

it develops fairly large fruit size whereas under non-irrigated con­

ditions (Quebec) the fruits tend to be rather small. It is a deeply

blushed, very attractive fruit, and it competes favourably with Mclntosh

(Fisher, 1971; Lapins and Fisher, 1972; Lareau and Granger, 1973).

However a physiological disorder, called Spartan breakdown, charac­

terized by a diffuse browning of the outer cortex immediately adjacent

to the epidermis of fruits in cold storage (Fig. 1) poses a serious

economic threat to the Spartan apple industry in British Columbia.

Its occurrence has been sporadic and not related to any obvious

year to year climatic difference (Lidster, 1972). However, it is

believed to be associated with calcium deficiency (Mason and McDougal1, 1974), large fruit size (Lidster et at. 1975), and high relative humidity in the cold storage atmosphere (Porritt and Meberiuk, 1973).

0 - 2 - '

Fig. 1. Summerland-grown Spartan apples severely affected by breakdown

when examined on June 12, 1975. They were harvested at optimum

maturity on October 3, 1974, and stored in polyethylene box • liners at 20 C and 92 to 94% RH • - 3- c

2. REVIEW OF LITERATURE

2.1. Cultural Factors Associated with Apple Storage Disorders

2.1.1. Introduction

Spartan breakdown is an internal disorder of fruits in cold

storage somewhat similar to other apple disorders generally clas-

sified by Smock (1977) as ''senescent breakdown disorders' even

though it is considered distinct enough to warrant a separate category.

Susceptibility to internal disorders of this type is clearly related

to orchard practices such as soil management and control of tree

vigour (Lidster et al. 1975). In another large group of apple di-

sorders the fruits are characterized by tissue pitting or corking

and in many cases cultural factors inducive to pitting are different

than those inducive to internal disorders such as Spartan breakdown

(Fidler et al. 1973). Nevertheless, both classes of disorders are

aggravated by low fruit Ca content (Shear, 1975) and, since many

cultural practices might affect fruit Ca (Sharples, 1973), both pitting

and internal disorders will be considered in this review.

2.1.2. Scion/rootstock relationships

Sharples (1973) indicated that more vigorous rootstocks often

lead to a greater incidence of bitter pit in scion cultivars suscep- c tible to that disorder. Wallace (1953) found that breakdown in Bramley's Seedling apple stored at 10 C was greater in fruits from trees on the - 4 -

semi-vigorous EM 4 than in fruit from trees on the very dwarfing

EM 9 rootstock. He also pointed out that scion cultivars on EM 5

(semi-dwarfing) were susceptible to breakdown. A survey conducted by

Lidster (1972) of 90 growers in the Okanagan Valley of British Columbia

revealed that the semi-dwarfing EM 7 was associated with less Spartan

breakdown than other rootstocks commercially used in that area.

However, a more recent study (Lidster et al. 1975) suggested that

rootstock was not significantly related to Spartan breakdown.

It is well known, however, that scion cultivars, irrespective of

rootstock, show particular weaknesses to different storage disorders.

For example, is known to be susceptible to bitter pit,

Jonathan to spot, Mcintosh to mealy breakdown,

to a breakdown following preharvest water core, to storage

scald and Spartan to Spartan breakdown.

2.1.3. Irrigation, pruning and thinning

Unpublished trial data collected by Reeney (1968) at Smithfield,

Ontario have shown that applying irrigation water to Spartan apple

trees late in the growing season improved the size of the fruit much

more than early season thinning. Furthermore, Spartan trees in the

Okanagan Valley of B.C. suffering from a lack of irrigation water

are always less vigorous and produce apples which are smaller in size.

Thus, adequate water is very important in sizing of Spartan apples. c However, excessive use of irrigation water with or without mulching - 5 -

(see also 2.1.4. second paragraph) have led to breakdown and other fruit disorders (Faust and Shear, 1968, van der Boon and Das, 1969).

For example, Jonathan spot was aggravated by high irrigation especially in conjunction with high N (van der Boon et at. 1970). In contrast, an adequate supply of irrigation water, particularly when applied at night, has improved fruit quality (Unrath, 1972; Guelffat'Reich et at.

1974). Finally, Quinlan (1969) found that fruit thinning of Laxton's

Fortune apple increased fruit dry weight and element content but had little effect on element concentration, with the exception that calcium concentration tended to be higher in thinned fruits at harvest. Dry orchard conditions, while inducing a higher incidence of bitter pit and other corking disorders (Faust and Shear, 1968), have not been associated with internal breakdown disorders.

Tree vigour may be related to the breakdown disorders associated with heavy pruning. It has been reported that severe winter pruning was associated with an increase in the incidence of bitter pit on apple (HilkenbUumer and Reinken, 1959; Refatti, 1959; Gorini, 1964; Faust and Shear, 1968). Heavy pruning has also been shown to be responsible for increased breakdown in Jonathan (Palmer, 1931) and of water core· in other cultivars (O'Gara, 1913; Faust et at. 1969). Heavily pruned

Mcintosh trees were found to bear large fruits of poor quality at

Frelighsburg, Quebec in 1970, 1971 and 1972 (Granger, 1970, 1971 and

1972). Wallace (1953) found that heavily pruned trees of Allington

Pippin were sensitive to breakdown. Similarly treated apple trees - 6 -

were also found to develop bitter pit (HilkenbHUmer and Reinken,

1959; Refatti, 1959; Gorini, 1964; Faust and Shear, 1968). Recent

information indicates that chemical pruning treatments applied 2 and

4 weeks after full bloom decreased significantly the incidence of

bitter pit in apple fruits (Jackson et al. 1976).

2.1.4. Soil management, soil type and mineral content

Clean cultivation is no longer recommended in modern orchards

because it in1.Tolves more work, is difficult to practice in stony

soils, and is detrimental to fruit quality (Wallace, 1953; Montgomery

and Wilkinson, 1962). Growing grass around trees in orchards has

improved significantly the keeping quality of fruit in Europe. In

general, these fruit develop fewer storage disorders than fruit from

cultivated orchards (Hilkenbftumer and Reinken, 1959; Landfald, 1962).

However, Delver (1972) found in Holland that bitter pit was greatly

reduced by rotovating, especially where the grass clippings were left

in situ. In a dry season grass vegetation was found to cause an

increase of bitter pit apparently because the grass was competing for

water and causing stress to the tree. By contrast, mulching and a

high level of humus in the soil have alleviated bitter pit and other

corking disorders in apples (Johansson, 1956; Hilkenblumer and

Reinken, 1959). According to Sharples (1973), sward exerts a bene­

ficial effect on internal disorders since it reduces excessive tree c vigour and serves to regulate supplies of water and nutrients. - 7 -

There is little evidence directly relating herbicide use to breakdown and other apple disorders. Nevertheless, in the Okanagan

Valley, most of the Spartan apple trees where the fruits were severely afflicted with Spartan breakdown in 1970 had been growing for a few years in herbicide-treated strips. Vigour is generally increased by this practice. Sharples (1973) cites unpublished reports from both

Holland and England suggesting that the absence of mechanical culti­ vation in herbicide-treated orchards permits greater development of surface roots than in clean cultivation and that water and nutrient uptake are more effective in herbicide-treated soils than in soils under grass or clean cultivation. Since an excess of either water or nutrients can more easily occur in herbicide-treated soils, special attention must be paid to irrigation and fertilization in order to avoid bitter pit or breakdown development of apple fruits. Lord et al.

(1970) showed that the nitrogen content of the leaves of different rootstocks was significantly increased by applying progressively higher rates of simazine.

Little has been reported on the effects of soil type on storage disorders. van der Boon et al. (1968) reported that the ratio of K and Mg to Ca is higher in leaves of trees on light sandy soil than on heavier soils. The same investigators (van der Boon et al. 1966 and

1968) reported that potash is probably more readily absorbed from sandy soils which would influence the level of exchangeable cations in the soil which could eventually adversely affect fruit keeping · - 8 -

quality. Furthermore, sandy soils are more likely to lead to moisture

stress which interferes with uptake of cations. Higher incidence of

scald in Lombarts Calville apples (Stenvers, 1969) and of brown heart

in apples (Nyhlen and Johannsen, 1964) have been found

in lighter soils. Mason (1966) hypothesizes that some clay soils of

the Okanagan Valley, B.C. produce softer apples because they are

paturally high in Mg and low in Ca compared to other sandy or silty

soils of the area.

A subsequent section (2.2) will discuss in more depth the asso­

ciation between nutrition and fruit disorders. However, it must be

pointed out at this time that the relationships between soil mineral

content and fruit mineral content is seldom clear-cut. Sharples

(1973) reports that even though storage disorders have often been

attributed to Ca deficiency no cleaT relationship to soil Ca exists. Nonetheless, Yamazaki et at. (1968) found a negative correlation between the occurence of bitter pit and Ca content of the sub-soil

in Japan but Ca content of the top 20 cm did not relate to bitter pit

incidence. They suggest that high K in the top soil may interfere

with Ca absorption and thus mask the Ca: bitter pit relationship there.

2.1.5. Growth regulator and fungicide sprays

Growth regulators:

The use of growth regulators has become popular in all apple c and pear growing areas of theworld. These substances are used to - 9 -

prevent fruit drop, improve fruit firmness, increase colour, hasten or retard maturity, control vegetative growth, promote flowering and promote fruit and flower abscission. · The effects of growth regulator sprays on fruit disorders has been adequately reviewed by Sharples (1973).

In general, those which reduce fruit size tend to reduce the

incidence of pitting and senescent disorders (Martin et at. 1968); those which advance ripening tend to aggravate senescence related disorders

(Allen, 1953); and others which delay ripening may have the converse effect (Looney, 1969).

Fungicides:

MOst fungicides have had no detrimental effect on the keeping quality of apples. However, in Europe, it has been reported that dimethyldithiocarbamate sprays (thiram, ziram, ferbam and tecoram), applied for the control of , increased the incidence of bitter pit in the cultivars Notarisappel (Keijer and Dijksterhuis, 1959),

Reinette du Mans (Paulin and Anquez, 1962) and Worchester (Kirby et at. 1968). The use of these fungicides has occasionally led to a reduction in crop rendering the apples subject to bitter pit

{Kirby et aZ. 1968; Sharples and Kirby, 1971).

2.1.6. Time of harvest and post-harvest treatments

Harvest date:

Harvesting at the proper stage of maturity is of paramount impor- - 10 -

tance to obtaining maximum keeping quality of apples. According to

Smock and Neubert (1950), if harvest and storage of apples that have

reached their optimum picking time is delayed for a week, there may

be a considerable increase in bitter pit development in storage. They

have also observed that delayed storage may increase the incidence

of breakdown and other storage disorders such as Jonathan spot and

spy spot.

On the other hand they stated that whenever picked too soon the

apples of certain cultivars may become subject to bitter pit or scald

(ibidem). Growers and researchers have learned that early picking

should be avoided for cultivars prone to superficial scald (Smock and

Neubert, 1950; Tindale, 1966). Wi1kinson (1966) has made the same

observation for cultivars susceptible to core flush.

Post-harvest treatments:

Ethoxyquin (Stop-Scald} or diphenylamine, (DPA, No-Scald DPA},

used as post-harvest dip treatments have been recommended commercially

for many years and have given, when used properly, 100% scald control

on Cortland, Mcintosh, Delicious and other cultivars (Blanpied and

Smock, 1963). These treatments also help to control other disorders.

For example, dipping apples at harvest in solutions

of 0.2% ethoxyquin or 0.16% DPA controlled internal browning in regular

storage at 00 C but in a modified atmosphere (15% co and 5% o ) DPA 2 2 doubled the incidence of core flush com~ared with other treatments c (Leblond and Morgat, 1971). Moreover, ethoxyquin and DPA increased - 11 -

the number of fruits with internal browning but adding benomyl fungi­

cide (Benlate) to the ethoXyquin dip solution gave some control of

browning. Wax (Sta-Fresh 200) gave 100% control of browning while

paper wraps increased browning (Leblond and Morgat, 1971).

Calcium dips:

Very recently a considerable amount of work has been conducted on

the effects of dipping fruit in calcium salt solutions at harvest as

a prestorage treatment. Bangerth et al. (1972) found that dipping

Jonathan apples in a CaC12 solution prior to storage greatly reduced the development of internal breakdown and reduced flesh softening.

Softening of Mclntosh apples was also reduced to a great extent by

dipping fruit 2 days after harvest in 4% CaC1 • The addition of 2 Keltrol, a commercial food thickener, at 3 g/l to retain more Ca

solution on the fruit, increased the effectiveness of the treatment (Mason et al. 1975).

Mason e~ at. (1974) first reported that CaC12 dips could greatly reduce incidence of Spartan breakdown and that adding thickeners to

:he CaC12 solution was of additional benefit. Porritt et al. (1975) found that dipping Spartan apples either in a solution of gibberellic

acid at 200 ppm or in a 4% solution of CaC1 or in a solution of 4% 2 CaC12 + 200 DPA prior to storage significantly reduced the incidence of internal breakdown in Spartan apples. Lidster (1975), using radio­

active Ca, found that early dipping (early to mid-Dctober) led to more c ~ 5 Ca absorption than late dipping (late November). Dipping Spartan - 12 -

apples in a 4% solution of CaC1 has become a recommended practice in 2 the Okanagan Valley.

Management of cold storage rooms:

It must be emphasized that the recommended conditions of storage for a given cultivar are often critical and that a slight deviation can cause serious trouble. A proper balance of temperature, relative humidity, co2 and o2 levels must be maintained in controlled atmosphere storage rooms if core flush, low temperature breakdown, co2 injury, etc. are to be avoided (Fidler et al. 1973}. Unfortunately, conditions known to enhance freshness and storage life may also promote the deve­ lopment of disorders in some fruits. For example, high relative humidity promotes Spartan breakdown development (Porritt and Meheriuk, 1973).

2.2. Nutritional Factors Associated With Storage Disorders

2.2.1. Prominent role of calcium

Of the essential elements, Ca was early recognized by Garman and Mathis (1956) as important in the mineral balance of apple fruits, especially in relation to storageability. This has been supported further by a recent paper by Martin et al. (1976) who states that Ca levels relate strongly to the storage disorders of Cleopatra apples.

Childers and Abdalla (1974} have stressed the importance of Ca nutrition in tree fruits: - 13 -

"Horticulturists are beginning to realize that while ea may be adequately present in a soil, a particular fruit tree or plant under some conditions is unable to get and/or move enough ea into the fruits. And this may cause various ea-oriented problems to appear such as bitter pit, cork spot, and physiological breakdown of apples, blossom-end-rot of tomatoes, and possibly other troubles as yet unidentified".

Ca has been reported by Mason et aZ. (1975) to have reduced greatly the

incidence of senescent breakdown on Spartan apples in British Columbia.

Shear (1972) reported that the percentage of fruit showing cork spot

was negatively correlated with the concentration of Ca in leaves and in

the flesh of the apple fruit. He observed that to assure commercial

control of cork spot the ea content of the flesh of

apple must be above 200 ppm on a dry weight basis. According to Drake

et al. (1974) bitter pit incidence could be predicted from Ca contact

in either leaf or peel of apples. It was also found that

scald, internal breakdown and decay were more prevalent when peel Ca

of Baldwin apples was below 700 ppm on a dry weight basis and that

the occurrence of bitter pit was inversely related to Ca levels (Bramlage

et al. 1974).

Many experiments have been aimed at improving the Ca level of fruits

through soil applications of ea salts. The purpose of applying Ca salts

to the soil may be two fold. First, when the pH of acid soil is raised

to 6, 6.5 or possibly 7 the absorption of most essential elements is

optimized (Childers and Abdalla, 1974), and secondly, to increase the

ea uptake by the plant, thus decreasing the incidence of physiological c disorders. A number of workers have studied the movement·of Cain fruit - 14 -

trees. According to ehilders and Abdalla (1974), ea supply should be rather abundant at the start of the growing season since ea applied to the root system moves most rapidly during the rapid metabolic activity which occurs early in the growing season. Applied to apple trees during this period, ~ 5ea did enter the fruits but when applied after terminal growth was completed, its presence in fruits could not be detected (Millikan, 1971). ~ 5 Ca applied to the root system of apple trees moves readily to the developing leaves and uptake occurs mainly during the period of cell division (Faust and Shear, 1970;

Link, 1974).

Bell and Biddulph (1963) working with isotopic calcium on tomatoes demonstrated that Ca ascended the stem by an exchange mechanism which apparently takes place in the xylem. Stebbins and Dewey (1972) found that in young apple trees ~ 5 ea moves primarily in the phloem but leaks into the xylem at increasing rates in the younger stem near the growing apex. Therefore, it appears that the mass flow idea does not apply to the movements of ea in fruit trees. This may partly explain why Ca moves so slowly in the plant and is often in short supply in fruit, resulting in physiological disorders.

Shear and Faust (1970) suggest that all of the ea used by each apple crop comes from the soil in that season. Mason and McDougald

(1974) revealed that Spartan apple trees treated with high levels of Ca salts in a nutrient solution and sand culture system bore fruits which had very little breakdown whereas apples from the trees which - 15 -

had a low Ca supply broke down severely. Garman and Mathis (1956)

observed that soil injections with Ca solutions were beneficial in

reducing incidence of bitter pit in Baldwin apples. Experiments in

Holland revealed that heavy applications of gypsum applied annually

~or several years decreased the incidence of bitter pit (van der Boon

et al. 1966 and 1968) but it took three years to reduce the incidence

of bitter pit with applications of CaN0 and Caso on a sandy soil. 3 4 Moreover, Chittenden et al. (1963) and Porreye and Piot (1964) found

that gypsum and other Ca salts were either ineffective or caused a

slight increase in bitter pit at least during the first two growing

seasons after their soil applications.

Foliar applications of Ca salts have generally proved to be

more effective than soil applications for controlling bitter pit and

breakdown in apple. Lewis and Martin (1973) used ~ 5Ca to demonstrate

that absorption from soil was poor, that it moved slowly in the tree,

and was immobilized before it reached the fruit.

The two most hygroscopic Ca salts, CaC1 and CaN0 , have proved 2 3 most satisfactory in controlling corking disorders of apples. They

were more effective than calcium lactate or acetate which also gave

some slight control (Baxter, 1960; Buchloh, 1960; Beyer, 1962;

Smock et al. 1962; Porreye and Piot, 1964; Schumacher and Frankhauser,

1964). Ca(H Po ) gave no control at all (Askew et al. 1960; Buchloh, 2 4 2 1960; Martin et al. 1960). It has been found in Belgium that an

equivalent amount of CaC1 was more effective than CaN0 in controlling c 2 3 - 16 -

bitter pit (van Goor, 1973).

To provide adequate control of bitter pit, 3 to 5 sprays per season of CaN0 or CaC1 may be necessary, preferably evenly spaced, 3 2 when the irrigation systems are not in use, and when the relative humidity is low since rapid evaporation of the spray droplets may speed salt penetration (Tukey, 1971). The most effective sprays were those applied near harvest (Sharples, 1971). In cases of very severe Ca deficiency, pre-storage Ca dips may give even better control of corking disorders (Tukey, 1971).

Looney (1977) reports that a single pre-harvest spray of 2.5 or

5% CaC12 was highly effective in reducing breakdown of Spartan apples.

2.2.2. Elements other than Ca associated with storage disorders

While Ca is generally considered the single most important element relating directly to the incidence of storage disorders (Mason and

McDougald, 1974), the levels of other elements such as nitrogen, potassium, phosphorus, magnesium and boron may relate to the incidence of fruit disorders in cold storage (Sharples, 1973) ·~

Nitrogen:

N has been found to relate to the incidence of bitter pit, break­ down, soft scald, scald, rotting and core flush of apples. In most cases, additional N aggravated the damage but in a few instances it had no effect or had beneficial effects (Sharples, 1973). - 17 -

.Q

In trials with Lawfam (Hill, 1952), Cox's Orange Pippin (Nyhlen,

1960; Chittenden, 1961), and Jonathan (Yamazaki et al. 1962) incidence

of bitter pit was increased as N levels were increased. However,

in other trials (Refatti, 1959; van Schreven et al. 1962; Hohmann,

1963; t-1eeks et al. 1965) additional N had little or no effects on

bitter pit incidence. Stebbins (1972) hypothesized that if N appli­

cations increased fruit set they might actually reduce the incidence

of bitter pit since it is well known that light fruit set is an

overriding factor• It was found by HilkenbaUmer and Kohl (1968) that

applications of N salts increased bitter pit in Cox apples grown on

soils of low Ca status but not o.n soil well supplied with Ca.

Shear and Faust (1970) grew York Imperial apples trees in sand with

nutrient solutions. In their trial high N treatments aggravated

the development of Ca deficiency symptoms on both leaves and fruits.

Not only the level but the form of N had a bearing on the incidence

of the disorders. A pot culture experiment revealed that more severe

symptoms of Ca deficiency appeared on trees fed with 75% ~TB 4-N plus 25% N0 -N than with 100% N0 -N (Shear, 1972). Even though No -N 3 3 3 was recognized as a superior form of N to use in order to prevent some

internal disorders, Stebbins (1972) commented that Shear's work

was executed under highly artificial conditions and that it would be

very difficult to feed NH -N to fruit trees in the orchard because 4 it is converted to N0 -N by bacteria in the soil before it reaches 3 very many of the tree roots. In a similar kind of study using soilless

0 culture, ammonium N reduced the Ca content in tomatoes and favoured the - 18 -

development of blossom-end rot (lUlcox et at. 1973). In pot culture

work on Jonathan (Martin et al. 1970), trees fed with urea bore fruits

which did not show symptoms of bitter pit whereas trees treated with

equal amounts of N supplied as (NH ) and NH were severely 4 2so4 4No3 affected.

Nitrogen additions.were also found to increase the incidence of

disorders other than bitter pit. For example, work on Jonathan (Tiller

et at. 1959; De Stanchina and Gorini, 1966), Cox's Orange Pippin

(Tiller et al. 1959; Herregods, 1970), Sturmer (Tiller et al. 1959},

Erwin Baur (Schubert, 1967), Bramley's Seedling and Worchester

Pearmain (Wallace, 1953) showed that the incidence of breakdown in

storage was aggravated by excessive additions of N to orchard soils.

The same treatments caused soft scald on Golden Delicious (Pratella,

1961) and favoured the development of superficial scald on Red Delicious

(Weeks et al. 1965), Golden Delicious (Herregods, 1970), Dunn's Favorite,

Sturmer Pippin and other cultivars (Tiller et al. 1959). High rates

of applied N have also been associated with low temperature injury in

Cox stored at 0 0 C from trees growing in grass but not from trees grown

under clean cultivation (MOntgomery and Wilkinson, 1962). High N

regimes have increased rotting of apples in storage (Wallace, 1953;

Montgomery and Wilkinson, 1962; Eaves et at. 1964). However, in some

trials (BUnemann and Ludders, 1960; Letham, 1969), fruit Ca content

has been increased due to application of N. Moreover, Eaves et al. c (1964) and Sharples (1973) found that core flush was less prevalent - 19 -

in fruits from trees fertilized with extra N.

The effects on storage disorders by foliar application of N salts as compared to their application on the soil have received very little attention. However, Blasberg (1953) found that urea sprays on

Mcintosh trees considerably reduced the firmness and the soluble solids content of the fruit.

The time of application of N may also influence the composition of the fruit at harvest and thereby affect storage quality. In a recent paper, BUnemann and Ludders {1975) demonstrated that in sand culture heavy N fertilization during the period of most vigorous shoot development, that is, during June and July, increased signifi­ cantly the incidence of bitter pit. In other experiments, high rates of N led to an increased amount of breakdown in Erwin Baur apples regardless of the time of application (Schubert, 1967). When used at a lower rate, more breakdown occurred in apples from trees fertilized in the spring.

Potassium:

K is found abundantly in actively growing regions of plants such as buds, young leaves and root tips, it functions primarily as a regulator of photosynthesis and an activator of enzymes (Epstein,

1972). Unlike Ca, it is highly mobile in plants where it is the most abundant monovalent cation (Meyer and Anderson, 1952). In apple fruits

K has been reported to influence the incidence of storage disorders - 20 -

such as low temperature injury, rotting, breakdown, scald, bitter pit, brown heart and core flush (Sharples, 1973).

Excessive levels of applied K increased the number of scalded

and rotted apples in storage (Nyhlen, 1960; Montgomery and Wilkinson,

1962; Weeks et aZ •. l965; Sharples, 1968). Similar treatments have

increased significantly the incidence of bitter pit on cultivars such

as Cox (Nyhlen, 1960), Red Delicious (Weeks et al. 1965) and others. Moreover, Oberly et aZ. (1968) found a positive correlation between

the K status of the leaves or fruits and bitter pit incidence. Core

flush (Hallace, 1953) and brown heart (Nyhlen, 1960) were aggravated

by K applications. However, beneficial effects of K on post-harvest

disorders have been observed. For example, foliar sprays of K salts

have reduced the incidence of breakdown in Cox's Orange Pippin

(Sharples, 1968; van der Boon et al. 1968). Similarly, soil dressings

with K salts have been shown to reduce the incidence of low temperature

injury in Cox's Orange Pippin (Montgomery and Wilkinson, 1962) and

Jonathan (Bllnemann et al. 1959).

The antagonistic effects of K on Ca and Mg uptake have been observed by many researchers. For example, K has been shown to depress the Ca

status of the fruits (Weeks et al. 1965). According to van der Boon

et al. (1966), a negative correlation exists between leaf Ca and fruit K

and Mg levels. Mason and McDougald (1974) indicated that as Mg and

K concentration increased in the flesh of Spartan apples there was a 0 corresponding decrease in Ca content. Trials conducted at East Mailing - 21 -

with apple rootstocks (Ford, 1966) revealed that more K, Ca and Mn

accumulated in the plant whenever there were low levels of Mg.

Sharples (1973) suggested that additions of K may depress Ca uptake

and this would explain the K effect on several of the storage disor­

ders •. However, Lidster et at. (1975) found that the combination of

K, Ca and B was a predictor of breakdown in Spartan apples and

suggested that K bad a direct effect rather than one of limiting the

concentration of Ca in apple flesh. They even recommended that under

the conditions which prevail in the Okanagan Valley of British Columbia,

apple flesh K should be less than 883 ppm fresh weight to minimize

Spartan breakdown.

Phosphorus:

Despite the relatively low requirements of apple trees for P, this

element often exerts beneficial effects on the keeping quality of pome

fruits when applied in proper quantities to be soil (Fidler et al.

1973). Unlike K, P tends to accumulate in seeds and fruits of growing

plants (Meyer and Anderson, 1952). It also acts as an activator of

some enzymes (Epstein, 1972) and since it is involved in the energy

transfer systems of plants it would be expected to be high in the

mitochondria.

A high degree of resistance to breakdown has accompanied increased

levels of P in apple fruits (Perring, 1968 and 1968A; Sharples, 1968).

Breakdown incidence has also been reduced by foliar application of c potassium dihydrogen phosphate in early summer (Martin et at. 1965). - 22 -

In soils where the plants are responsive to P fertilization, such as

certain orchards soils in Australia and New Zealand, applications of

P have reduced breakdown (Tiller et al. 1959; Martin et al. 1965;

Letham, 1969). The beneficial effect of P on the keeping quality

of apples were discussed by Sharples (1973). He reported that

phosphorus had been shown to be necessary for the uptake of calcium

by certain cereal crops and its relationship with breakdown may have

been due to a similar effect in apples.

No effect of P on the incidence of other storage disorders such

as core flush, bitter pit, scald, etc., have been reported. Further

comments on the role of P at the cellular level are found in Chapter

2.2.3.

Magnesium:

Mg, the only mineral constituent of the chlorophyll molecule, is

primarily found in chloroplast-containing tissues but also in seeds

and mature fruits (Meyer and Anderson, 1952). Large quantities of Mg

in apple fruits relative to the Ca level may cause an increase in

bitter pit incidence (Garman and Mathis, 1956; Askew et al. 1959 and

1960; van der Boon et al. 1966; Sharples, 1968). Apples containing low

levels of Mg may be subject to low temperature injury and to senescent

breakdown (Perring, 1968, 1968A; Sharples, 1968). Martin et al. (1969),

in experiments with sprays of Mg salts on Cleopatra apple trees, found c a negative correlation between scald incidence and fruit Mg. In most cases, heavy applications of Mg salts either in the form of soil - 23 - c

dressings or foliar sprays have increased the Mg:Ca ratio in the

fruit (Garman and Mathis, 1956; van der Boon, 1966 and 1968) and

often times have had deleterious effects on bitter pit (Martin et at.

1960; Porreye and Piot, 1964; van der Boon et al. 1966 and 1968).

Granger 1974 (unpublished) observed that when the leaf Ca level was

very high, i.e. at or above 1.6% in the case of the cultivar Mcintosh, it had a depressing effect on the Mg level. This confirms previous

observations by Sharples (1973). Similarly, Mason and McDougald (1974)

found that the Mg concentration in Spartan apples, from trees growing

in sand culture, increased with decreasing Ca supply in the nutrient

solution. flhen applied late in the season, Mg sprays did not affect

the incidence of bitter pit or breakdo~nn of Cox's Orange Pippin and

Jonathan apples (van der Boon et al. 1968).

Boron:

Like Ca, B in most plants is not a readily mobile element and

usually the range between the amount of B necessary for the best development of a plant and that causing injury is very narrow

(Meyer and Anderson, 1952). In fruit nutrition, both extremes have

led to storage disorders and a number of studies have suggested a role for B in maintaining good fruit quality.

When soil B levels have become excessive, the storage life of

apples has been reduced and symptoms such as earlier changes in ground

colour, stimulation in post-harvest respiration rate, changes in enzyme

c activity during maturation and storage, water core, breakdown or - 24 -

scald have developed (Philips and Johnson, 1943; Haller and Batjer,

1946; Holbecke, 1946; Thomas, 1960; Bramlage and Thomson, 1962 and

1963).

On the other hand, other corking disorders such as cork spot, corky core and drought spot which are not strictly storage problems were found to be related to B deficiency and occured quite often under relatively dry climatic conditions (McLarty et al. 1936; Wilcox,

1938; Wilcox and Woodbridge, 1943).

The role of B in the Ca metabolism of pome fruits has been examined recently by several workers. Lidster et al. (1975) found that apple flesh Ca was positively correlated with flesh B and that these two elements were significantly and negatively correlated with Spartan breakdown. Faust and Shear (1968) suggested that B may be required for the transport of Ca but this could only be demonstrated when B rather than Ca was the limiting factor. Cork spot in York Imperial apples, which was controlled to a certain extent by E sprays, was controlled more effectively by a mixture of B and Ca (Stiles, 1964;

Hewetson, 1966). Several hypotheses have been proposed regarding the

Ca-B relationship. Stebbins (1973) submitted the two following hypo­ theses: First, as observed in apple, when leaf B increased fruit Ca decreased and fruit breakdown increased. Excessive B may therefore induce breakdown by displacing Ca from the fruits to the leaves.

Secondly, Minarik and Shive (1939) report that B deficiency was associated with higher moisture content of soybean and excess B gave - 25 -

the lowest Ca levels in the leaves. Excess of B might therefore induce

breakdown by reducing the absorption of Ca by the roots. This might be

caused by a chemical reaction between B and Ca forming calcium borate

in the soil or perhaps in the plant. Such a reaction happens in the

soil following liming (Stebbins, 1973). In 1966, Granger (unpublished)

observed that the application of 50 pounds of hydrated lime to

15-year-ol~ and Joyce apple trees produced severe fruit symptoms

of B deficiency. The untreated trees bore normal fruits. Similarly,

Reeve and Shive (1944) have shown that B toxicity may sometimes decrease with increasing concentration of Ca. Lidster et at. (1975) found that

the ratio of Ca to B in flesh of apples from British Columbia was not

a better predictor of Spartan breakdown than Ca alone.

Micro-nutrients:

Applications of as many as 36 elements, most of which are consi­

dered as non-essential, such as strontium, vanadium, tungsten, etc.,

failed to correct any physiological disorders of apples (Barnicoat, 1963; Martin et al. 1965). However, Metzner and Hllbner (1971) reported

that zinc phosphate sprays gave some degree of control of bitter pit

on Cox's Orange Pippin apples. Similarly, Pais and Peth8 (1971) found

that Jonathan spot incidence could be greatly reduced by sprays contai­

ning 0.15% Ca enriched with Zn or Ni ions at 0.05 ppm.

2.2.3. Cytological, physiological and environmental factors c C¥tological factor~: Several storage disorders, such as bitter pit and breakdown, are - 26 - c

reported to be more prevalent in large apple fruits (Martin, 1953,

1954 and 1954A; Faust et at. 1969; and Lidster et at. 1975). The

question raised here is whether fruits with relatively large cells

are more vulnerable to these disorders. Thinning trials, used to

increase fruit size and thus increase susceptibility to bitter pit and

breakdown (Bain and Robertson, 1951; Robertson and Turner, 1951;

Martin and Lewis, 1952), showed that the disorders were primarily as­

sociated with the mineral composition of the fruit and only secondarily

with mean fruit size regardless of the size of the cells or their

total number (Martin et at. 1954 and 1965). On the other hand, positive

correlations between internal breakdown and mean cell size were found

for several apple cultivars .(Martin et al. 1954 and 1965; Letham, 1961).

But again, the effect of fruit N content was greater than the effect

of cell size alone (Letham, 1961; Martin et at. 1965). Other workers

in England and New Zealand failed to find consistent effects of cell

volume on storage disorders in apple (Montgomery and Wilkinson,

1962; Jackson, 1967; Sharples, 1968A). Thus, it appears that both number

and size of cells contribute to larger-sized fruits but it is unclear

which of these two factors is most important. Increasing cell size

correlated with reduced P content of apple fruits (Letham, 1969).

Since under marginal levels of P .a decline in the level of phospholipids

may bring about the reduced membrane stability associated with breakdown,

this might explain the relationship between cell size and storage quality c, (Sharples, 1973). - 27 -

Physiological factors:

Among the cell biochemical compounds, oxalic acid has been found to induce Ca deficiency in tobacco (Brumagen and Hiatt, 1966) and it inactivated Ca in apple fruits (Liege!, 1972). According to Stebbins

(1973) when a high level of N0 occ.urs in the different parts of an 3 apple tree it is accompanied by high levels of Ca as insoluble oxalate.

A certain percentage of this Ca comes from the fruits where it may become deficient. Stebbins et al. (1972) further indicated that Ca oxa- late is deposited as crystals in apple stem, petiole and fruit tissues.

Calcium oxalate crystals were found in Jonathan apples which had internal breakdown. Ca from intensive Ca treatments raised the ascorbic acid level of apple flesh six fold (Bangerth, 1974). This acid in turn may retard fruit senescence.

Bangerth et al. (1972) also found that infiltration of fruit with sorbitol produced internal breakdown symptoms on Jonathan apples. No such breakdown symptoms developed from infiltrations with sucrose or glucose.

Ca has been found to be essential for the maintenance of the / plasma membrane and Marinos (1962 and 1963) showed that plasma and vacuolar membranes disintegrate when there is a specific lack of Ca. Rousseau et al. (1972) studied changes in membrane permeability of apples in storage and concluded that Ca sprays helped maintain cellular compartmentalization and thereby prevented the development of some storage disorders. - 28 -

Assuming that low-ea apples have a higher tissue permeability

than high-ea fruits, Bangerth (1974) hypothesized that for apples

affected by bitter pit, if the tonoplast gets more permeable, acids

as well as phenols from the vacuole can penetrate more readily into

the cytoplasm and destroy or coagulate enzymes and damage the mito­

chondria and other cellular particles.

Another theory suggests that permeability of the cell membrane

is regulated by the ratio of multivalent to univalent ions. According

to this theory, ea could bind the anionic groups of protein and phos­

photidic acids and provide a more rigid and less permeable structure

than when univalent ions are present (Hofmeister, 1954; Umrath, 1956;

eollander, 1957).

Once harvested a fruit no longer has access to water and nutrients,

· and its principal interchanges with the environment become the loss of

H and and the uptake of • The rate at which apples deteriorate 2o co2 o2 or age in storage is often positively related to their respiration rate;

Mitochondria, which are responsible for respiration, could, in the

presence of a source of energy, accumulate ea in quantity (Bangerth,

1974). However, no clear-cut evidence that ea exerts a specific action

on mitochondria could be found by Bangerth (1974) who pointed out that

other workers have found that Ca can either reduce or stimulate res­

piration of mitochondria depending on the sequence in which the 0 substrate is added to the assay medium. At any rate, Faust and Shear (1972) have suggested that low Ca fruits respire at a higher rate. Looney - 29 - c

(1977), however, did not find such a relationship with Spartan apples.

Another physiological factor associated with storage disorders

is transpiration rate of plant organs. This has interested a few

workers since it has been found to be positively correlated to Ca

uptake. Stebbins and Dewey (1972) discovered that Ca accumulation in

apple leaves increased with an increased rate of transpiration. How­

ever Ca was found to be low in the apple fruit though the other parts

of the trees proved to be well supplied with Ca. Lewis and Martin

(1973) injected a ~ 5 calcium chloride solution into a fruiting branch

of a Merton tree 8 weeks prior to harvest and found that leaves and

buds on the injected branch accumulated 95% of the recoverable Ca.

The fruits accumulated the remaining 5% of which only a very small part

was in the calyx end. Link (1974) attributes this low Ca content to

the poor transpiration rate of fruits. A practical application of this

idea is the maintenance during the growing season of a rather low

leaf/fruit ratio on trees bearing a light fruit load based on Knowlton's

and Hoffman's (1930) findings that a low leaf/fruit ratio of 10 to 25

caused no breakdown in storage whereas leaf/fruit ratios from 30 to

50 led to increasing amounts (up to 60%) of breakdown in storage. A

low leaf/fruit ratio would increase transpiration by the fruits relative

to that by the leaves. This idea is consistent with the summer pruning

practice suggested to control Spartan breakdown in British Columbia c (Mason et at. 1973). Looney (1977) found that the apples. located in the top of the tree - 30 - c

canopy were lower in Ca. This finding suggests that high leaf

transpiration may lead to a loss of Ca from the fruits to the leaves.

Environmental factors:

Thus, excessive loss of water vapor from fruit trees may aggra­

vate some disorders by increasing leaf Ca content at the expense of

fruit Ca. That could explain the greater incidence of bitter pit on

apple in arid Australia than in humid England (Shear, 1975) •. However,

in cold storage after the apples are harvested the opposite case has

been observed by Porritt and Meheriuk (1973). They found that 40%

of the Spartan apples stored in 92-94% relative humidity developed

breakdown whereas only 2.8% of them broke down when the fruit was

stored in 80% R.H. Many of the factors discussed so far could be

affected by altered moisture supply and the moisture content of a

fruit becomes an extremely complex subject because it involves inter­

actions with soil moisture, transpiration rate, and other factors.

Little information is available concerning direct or specific

effects of light on the development of storage disorders. Wallace

(1953) reported higher incidence of bitter pit in apples grown in

exposed positions on the tree and Jackson et al. (1971) showed that

the use of shade on fruit trees reduced the incidence of bitter pit on

Cox's Orange Pippin apples. Looney (1977) demonstrated that exposed

Spartan apples tended to have lower Ca levels and developed more

breakdown. However he attributed this effect to a Ca transport

problem rather than to light exposure. Helms and David (1973) experi- ~ 31 -

menting with PhaseoZus vuZgaPis showed that light could increase the

Ca content and dry weight of all organs except cotyledons and hypoco- tyls and that white light was more effective than red light in decreasing the incidence of hypocotyl collapse which is a severe symptoms of

Ca deficiency. Shear {1975) hypothesized that, under the influence of light, an increased photosynthetic activity might increase the rate of fruit enlargement and thus further dilute the Ca that was moved into the fruit.

Strongly associated with sunlight, temperature by itself may have an indirect influence on the incidence of fruit disorders. With tobacco plants an increase in temperature from 21-23 0 C to 29-30 0 C favored the development of very severe Ca deficiency symptoms (Chang et al. 1968}.

Similar results were obtained on apple by Fisher et al. {1931) who found that high temperatures shortly before picking increased signifi- cantly the incidence of water c~re and Sharples (1973) mentioned that this disorder occurs usually on a large scale only after unusually hot summers or when seasonal conditions favor the production of low

Ca apples. - 32 -

3. EXPERIMENTS AND RESULTS

3.1. Some Differences Between Quebec (Fresniere) and British Columbia

(Sunnnerland) Spartan Apples

3.1.1. Physical properties and chemical constituents as they

relate to Spartan breakdown

3.1.1.A. Materials and methods

Spartan apples from representative orchards in British Columbia and in Quebec were compared. The orchards selected in British Columbia were on the Agriculture Canada Research Station at Summerland and in

Quebec the holdings of Mr. Jean-claude Spenard of Fresniere, Co.

Deux-Montagnes were used. In each location the same fruit selection technique was employed: Both the Quebec and B.C. Spartan apples were picked at their optimum picking maturity. The fruit of sixty randomly chosen bushel (bu) boxes (approx. 18 kg/bu) were mixed thoroughly and sorted into size categories of small, medium, and large apples in

Quebec and medium, large and extra large for B.C. The size of apples in each class and location is shown in Table 1. Five bushels in each size category were used for the experiment. Each apple was carefully measured with a size gauge. One day after harvest the Quebec-grown

Spartan apples were air-freighted to the Summerland Research Station.

They arrived in good condition one day later (Fig. 2, top) and were stored at 10 C after they had been transferred into orchard boxes with - 33 -

' perforated polyethylene liners (Fig. 2, bottom) to maintain a high level of relative humidity (92 to 94% RH) around the fruits.

Figure 2 - Top: Spartan apples from Fresniere, Quebec as they arrived

at Summerland, B.C., Oct. 7, 1974.

Bottom: Spartan apples transfered to wooden bushel boxes with a

perforated polyethylene liner to increase the relative • humidity around the fruit during 1 0 C storage. - 34 - c Table 1. Size designation of apples used in the experiment

Category Size Province Diameter in centimeters 1 Counts

Quebec Small 5.11 to 5.60 cm 230

Quebec Medium 6.12 to 6.60 cm 185

Quebec Large 6.90 to 7.39 cm 155

B.C. Medium 6.12 to 6.60 cm 185

B.C. Large 6.90 to 7.39 cm 155

B.C. Extra 7.90 to 8.95 cm 95 Large

1 . The number of apples of this size which would fit into a commercial

1 bu box. - 35 -

Table 2. Dates when samples of each class of Spartan apples were

processed in the laboratory

1 1 Date Sample no. Date Sample no. 1 2 3 1 2 3

2 Oct. 9 BCL Nov. 1 QM u 10 BCEL " 6 QL " 11 BCM u 7 QL u 17 QS " 8 BCM BCM .. 18 QM lt 9 BCL

'fl 21 QL .. 11 BCL " 22 QS tl 12 BCEL BCEL " 23 QM " 31 QS

1 The quantity of apples processed for samples 1 and 2 was 15 and

for sample 3• 20 to make up a total of 50 apples per class

2 BCL • B.C. large, BCEL • B.C. extra large,

BCM = B.C. medium, QS • Quebec small, QM = Quebec med~um QL = Quebec large c - 36 - I Figure 3. Apparatus used to measure

fruit specific gravity. The fruit

of a known weight is immersed with

a tripod plunger. The balance (tared

between each fruit) records the force

required to submerse the apple in

water.

Specific apple wt (g) gravity flotation force (g)

Three groups of apple samples were randomly selected for each of

the 6 categories shown in Table 1. One group of 5 apples was used for

carbon dioxide and ethylene release studies as will be described in

Chapter 3.1.2. Another group comprised of 50 apples was used for

physical and chemical analyses as seen in the next few pages. The

remaining fruits, 5 bushels of 100 fruits each, were stored at 1°C for

8 1/2 months. On June 16, 1975 immediately after removal from storage

each apple of this group was examined for breakdown and rotting and

pressure tested on opposite sides of each fruit. The 50 apples from

each size and location used for physical and chemical analyses were

taken from cold storage between Oct. 9 and Nov. 12, 1974. To minimize

effects of time in storage a sampling schedule was followed (Table 2).

Physical criteria assessed for each apple were percentage of

surface with red colour, specific gravity, firmness and moisture con- • tent. The percentage of red colour for each apple was visually assessed . '( - 37 c by a reference to a reference to a standard apple having 90% red colour

and 10% ground colour according to experienced colour judges and preci-

sely measured with a colour meter. Specific gravity was determined by an

application of Archimedes principle (Fig. 3). Fruit firmness was

measured with a Magness-Taylor pressure tester equipped with a 1.1 cm

diameter tip. This instrument, also called a penetrometer, was attached

to a vertical standard 15 cm above and parallel to the surface of a

laboratory table. Each fruit was pressure tested at 3 different loca-

tions. The peel was removed from each of the 3 spots with a paring

knife. The percentage of peel moisture of each fruit was calculated

from the difference between the peel fresh weight and the peel dry

weight (after freeze drying) of each sample. For example, the peel

moisture of a typical sample was calculated as follows:

11.2 g (fresh wt) - 2.04 g (dry wt) a 9.16 g

9.16 X --=-- 11.2 100

916 x • ---- = 81.786% moisture 11.2

The percentage of moisture in the flesh tissue of each fruit was

·determined in the same way.

The fruit peel and the flesh sectors obtained were treated as

described in Figures 4 to 7.

Chemical analyses included measurement of soluble solids and

titrateable acidity of the juice pressed from 3 of the 8 sectors - 38 - I

Fig. 4 - Top: Hand-driven apple peeler and corer used to separate

peel and flesh of each fruit.

Bottom: Each apple was sliced into 8 uniform sectors. Three

(those with holes from the penetrometer) were used for

the determination of juice acidity and soluble solids

content. The remaining 5 sectors and the peel string • were analyzed for N, P, K, Mg and Ca content. - 39 - I

• Fig. 5 - The peel and the flesh prepared for freeze drying • - 40 - '

Fig. 6 ~ Top: Flesh and peel samples being placed into a laboratory

freeze dryer.

Bottom: Dry samples in polyethylene bags. These samples were

held in a low humidity room until they were analyzed • for mineral content. - 41 - '

Fig. 7 - Collecting and analyzing juice.

Top: Hand juice extractor. A few drops of the composite juice

sample collected in this manner were used to determine

% soluble solids with a hand-held refractometer.

Bottom: A 3 ml sample was titrated to pH 8.1 with 0.1 N NaOH

and acidity was calculated as % malic acid. The

instruments shown are a Coming pH meter and a Dosimat • Model E 415 titrimeter • - 42 -

0

obtained from each fruit. A total of 5 peel and flesh sectors were

dried and then analyzed for N, P, K, Mg and Ca.

The juice acidity expressed as per cent malic acid was calculated

as follows:

NA VA =NB VB

where NA = Acid Normality

VA = Acid Volume NB = Base Normality

VB = Base Volume

The gram molecular weight of malic acid is 134 and, since 1 molar malic acid is 2 normal, 134 = 67. For a sample which needed 2.43 ml 2 of .101 N NaOH to titrate 3 ml of juice to a pH of 8.1 then:

NA • NB VB = .101 X 2.43 = .0818 VA 3

% Acidity as Malic = .0818 x 67 = .5481 10

The fresh weight of the 5 sectors used for mineral analysis was

carefully recorded along with the fresh weight of each individual peel string. _They were then put in a deep freezer at -28.8 0 C for 3-4 days

and then placed in a freeze dryer (Fig. 6) for 36 hours from which

they were transferred into sealed polyethylene bags and stored fmme-

diately in a special low humidity cool storage room where they were

re-weighed. They were held for 3 weeks under these conditions and then

transferred to a freezer until they were analyzed for mineral content. 1 - 43 -

For mineral analysis both the peel and the flesh were ground with

a Wiley mill, transferred into separate polyethylene bags tightly

closed with rubber bands and stored in a freezer at -23.3°C. Total

nitrogen was determined by the Kjeldahl method.

One gram of each dry apple flesh or peel tissue sample, in 50 ml

beakers, was placed into a muffle furnace for 12 hours at 475 0 C. The

dry-ashed tissue was then taken up with 25 ml of 0.5 N hydrochloric

acid and K, Zn, Mg and Ca were determined by atomic absorption spectro-

photometry. The atomic absorption spectrophotometer used for this

analysis was a Techtron Model AA-3 equipped with an R 136 photomul­ tiplier having a wave length range of 4000 to 8000 R. When the aqueous solution of the metal salts from each apple sample were sprayed

into a 10 cm narrow-slit flame, the atoms of the elements of the samples

were excited to the point where they became atomized and absorbed the

light of a specific lamp. Phosphorus was determined spectrophotometrically

by the phosphomolybdovanadate procedure of Kitson and Mellon (1959). A

Spectronic 20 spectrocolormeter was used for this determination. The

amount of phosphorus contained in each fruit sample was obtained by

referring its transmittance (%) to a standard curve.

3.l.l.B~ Results

3.l.l.B.l. Development of breakdown and rots in cold storage c When stored under the conditions described, fruits from both B.C. and Quebec began showing symptoms of breakdown after 6 1/2 months - 44 -

in storage. When examined after 8 1/2 months, there were some subs­ tantial differences between the Quebec and B.C. lots (Table 3 and

Figs. 8 and 9). There was 57.15% as much breakdown in the Quebec fruit as in the B.C. fruit of the same diameter. Breakdown tendency was positively related to fruit diameter in fruits from both regions.

The medium and large apples from B.C. were more susceptible to break­ down than the medium and large apples from Quebec. The extra large fruits were notably more prone to the disorder than the other sizes

(Table 3 and Fig. 8).

A general trend was that larger fruit had a higher incidence of decay in storage (Table 3). The difference among each group of apples was not statistically significant although in total the

Quebec fruits were significantly less susceptible to rotting than the B.C. fruits. The rots on the apples were identified as being

Peniciliun e:r:pansum Lk. ex Thorn., Botrytis cinerea Pers. and GZ.oeosponum spp.

3.l.l.B.2. Fruit mineral content

Summaries of the data for N (total), Mg, K, P, Ca, and Zn in peel and flesh tissue of the 3 size categories of Quebec and B.C.

Spartan apples are presented in tables 4, 5, 6, 7, 8 and 9 respec­ tively.

Total Nitrogen. There was no location effect on total N nor any clear relationship between total Nand fruit size (Table 4). At both - 45 - c

locations total N of the flesh was about 48% of the peel total N

content. It would appear that the Quebec and B.C. fruit were grown

on trees of comparable vigour which should bolster the validity of

tbe other comparisons made. The total N content of the fruit showed

no significant relationship to breakdown (Table 14).

Magnesium. Peel Mg levels were clearly high in B.C. apples

(Table 5). On a dry weight basis, peel Mg was about 3 times the

flesh level in Quebec and about 3.5 times the flesh level in B.C.

fruit. Larger fruit tended to have higher levels of peel Mg at both

locations. Flesh Mg was similar in Quebec and B.C. fruit and the

relationship of flesh Mg to fruit size was unclear, although the

extra large B.C. apples did display significantly higher levels.

Peel Mg was among the best predictors of breakdown (Table 14 and

Fig. 11).

Potassium. Both flesh and peel K content were higher in B.C.

fruit (Table 6). Interestingly, peel and flesh levels were very

comparable at both locations. Flesh K levels tended to be slightly

higher than peel levels in Quebec fruit whereas the reverse was true

of B.C fruit. At both locations there was a slight tendency for larger

apples to have more K per unit dry weight of peel or flesh. Flesh K

was one of the best predictors of breakdown (Table 14 and Fig. 12).

Calcium. Peel Ca levels were about 3 times the flesh levels

0 on a ppm dry weight basis at both locations (Table 7). Larger apples - 46 -

Table 3. Per cent breakdown and rotting of apples of various

average diameters from Quebec and B.C. examined 8 1/2

months after harvest

1 Location Size category n Per cent breakdown Per cent Rotting

2 2 Quebec Small 5 8.80 a 2.8 a

Quebec Medium 5 14.60 ab 2.8 a

Quebec Large 5 23.12 abc 3.0 a B.C. Medium 5 27.80 be 3.6 a

B.c. Large 5 38.20 c 5.4 a " B.C. Extra Large 5 68.44 d 5.8 a

2 2 Quebec Medium & Large 10 18.86 a 2.9 a

B.C. Medium & Large 10 33.00 b 4.5 b

2 2 Quebec Small 5 8.80 a 2.8 a

Quebec & B.C. Medium 10 21.20 b 3.2 a Quebec & B.C. Large 10 30.66 b 4.2 a

B.C. Extra Large 5 68.44 c 5.8 a

1 80 to 100 apples made up each unit evaluated

2 Mean separation within columns by Scheffe's (1950) test performed at the 5% probability level c - 47 -

ISO

!B. C. \60 IE.L_= -~)(tra_Jargef L=Large .,~ M= Medium S Small 1~ 1so /0J 10 :o I~ lW 140 I~

\30

IS

\-5 rs r1 · la IMEAN APPLE DIAMETER (cm)

Fig. 8. Spartan breakdown development after 8 1/2 months of storage c at 2°C and high relative humidity. - 48 -

\EL

Is. c. IM EL = Extra L. a. rgr­ L Large M= Medium /oJ S = Small - .

/S

11oo r2oo /300 j MEAN FRUIT WEIGHT (G) ---~~·----~-~. ~~---·--·-~--...... ------~~--...... ~--'--

Fig. 9 Relationship between fruit weight and breakdown in Spartan apples. - 49 - c

Table 4. Total nitrogen content (% dry weight) of peel and flesh

tissue of B.C. and Quebec Spartan apples

Location Fruit size n Peel N Flesh N

1 1 Quebec Small 50 .307 a .149 a

Quebec Medium 50 .306 a .138 a

Quebec Large 50 .329 a .161 a

B.C. Medium 50 .297 a .143 a

B. C. Large 50 .320 a .142 a

B.C. Extra Large 50 .315 a .162 a

1 1 Quebec Medium & Large 100 .318 a .150 a

B.C. Medium & Large 100 .309 a .143 a

1 1 Quebec Small 50 .307 ab .149 a

Que. & B.c. Medium 100 .302 a .140 a

Que. & B.C. Large 100 .325 b .152 a

B.C. Extra Large 50 .315 ab .162 a

1 Mean separation, within columns, by Scheffe's (1950) test performed

at the 5% probability level - so -

were somewhat lower in both peel Ca and flesh Ca. B.C. apples were marginally lower than Quebec fruit in both peel and flesh Ca but these differences were not statistically significant.

Phosphorus. B.C. apples were twice as high in peel P as Quebec apples (Table 8). Flesh P was also significantly higher. It is also noteworthy that flesh and peel P levels were very similar in the Quebec fruit but peel P in the B.C. fruit was nearly twice that of the flesh. At both locations there was a tendency for the largest apples to contain the most flesh P. This tendency was less evident in the peel. Flesh P was among the best predictors of breakdown

(Table 14 and Fig. 14).

Zinc. Although some data, in retrospect, appeared unreasonable and were therefore thrown out, it: appears that Quebec apples were somewhat higher in tissue Zn levels (Table 9). No clear relationship between fruit size and Zn levels immerged. At least in the B.C. samples, the flesh and peel Zn levels were quite comparable. - 51 -

Table 5. Magnesium content (ppm dry weight) of flesh and peel

of Spartan apples of various sizes from Quebec and B.C.

Location Fruit Size n Peel Mg Flesh Mg

1 1 Quebec Small 50 646.59 a 228.25 a

Quebec Medium 50 650.66 a 222.70 a

Quebec Large 50 676.95 ab 228.25 a

B.C. Medium 50 717.15 b 229.56 a

B.C. Large 50 787.55 c 231.15 a

B.C. Extra Large 50 871.40 d 250.70 b

1 1 Quebec Med. & Large 100 663.81 a 225.47 a

B.C. Med. & Large 100 752.35 b 230.35 a

1 1 Quebec Small so 646.59 a 222.17 a Que. & B.c. Medium 100 683.90 b 226.13 a

Que. & B.C. Large 100 732.25 c 229.70 a B.C. Extra Large so 871.40 d 250.70 b

1 Mean separation, within columns, by Scheffe's (1950) test performed

at the 5% probability level - 52 -

Table 6. Potassium content (% dry weight) of peel and flesh

tissue of Quebec and B.C. Spartan apples

Location Fruit Size n Peel K Flesh K ·

1 1 Quebec Small 50 .512 a .556 a

Quebec Medium 50 .526 a .558 a

Quebec Large 50 .605 a .611 ab

B.C. Medium 50 .758 b .676 b

B.C. Large 50 .749 b .658 b

B.C. Extra Large 50 .798 b .769 c

Quebec Me d. & Large 100 .566 a 1 .585 a1 B.C. Med. & Large 100 • 754 b .667 b

1 1 Quebec Small 50 .520 a .556 a

Que. & B.C. Medium 100 .642 b .617 b

Que. & B.C. Large 100 .677 b .635 b B.c. Extra Large 50 .798 c .769 c

1 Mean separation, within columns, by Scheffe's (1950) test performed at the 5% probability level c - 53 -

Table 7. Calcium content {ppm dry weight) of peel and flesh

tissue of Quebec and B.C. Spartan apples

Location Fruit Size n Peel Ca Flesh Ca

1 1 Quebec Small 50 712.3 a 228.0 a

Quebec Medium 50 665.0 ab 217.9 ab

Quebec Large 50 610.9 ab 196.4 ab

B.C. Medium 50 622.0 ab 189.6 b

B.C. Large 50 631.5 ab 188.7 b

B.C. Extra Large 50 586.7 b 175.9 b

1 1 Quebec Med. & Large 100 638.0 a 207.2 a

B.C. Med. & Large 100 626.8 a 189.2 a

1 1 Quebec Small 50 712.3 a 228.0 a

Que. & B.C. Medium 100 643.6 ab 203.7 b

Que. & B.C. Large 100 620.8 b 193.5 b B.C. Extra Large 50 586.7 b 175.9 b

1 Mean separation. within columns, by Scheffe's (1950) test performed

at the 5% probability level - 54 -

Table 8. Phosphorous content {ppm dry weight) of peel and flesh

tissues of Quebec and B.C. Spartan apples

Location Fruit Size n Peel P Flesh P

1 1 Quebec Small 50 556.3 a 505.4 a

Quebec Medium 50 534.8 a 503 .. 1 a

Quebec Large 50 626.5 a 582.9 ab

B.C. Medium 50 1095.0 b 649.5 b

B.C. Large 50 1188.6 b 700.4 be

B.C. Extra Large 50 1144.4 b 762.3 c

1 1 Quebec Med. & Large 100 580.6 a 543.0 a

B.C. Med. & Large 100 1141.8 b 674.9 b

Quebec Small 50 556.3 a 1 505.4 a 1

Que. & B.C. Medium 100 814.9 b 576.3 b Que. & B.C. Large 100 907.6 b 582.9 b

B.C. Extra Large 50 1144.4 b 731.3 b

1 Mean separation, within columns, by Scheffe's (1950) test performed at the 5% probability level c - 55 -

Table 9. Zinc content (ppm dry weight) or peel and flesh tissue

of Quebec and B.C. Spartan apples

Location Fruit Size n Peel Zn Flesh Zn

1 Quebec Small 50 5.44 a

Quebec Medium 50 7.18 a

Quebec Large 50 4.41 6.59 a

B.C. Medium 50 2.79 2.54 b

B.C. Large 50 2.93 1.72 b

B.C. Extra Large 50 4.02 5.70 a

1 Quebec Med. & Large 100 6.89 a

B.C. Med. & Large 100 2.86 2.13 b

Quebec Small 50 5.44 a 1

Que. & B.C. Medium 100 4.86 a

Que. & B.C. Large 100 3.67 4.16 a B.C. Extra Large 50 4.02 5.70 a

1 Mean separation within a column by Scheffe's (1950) test performed at the 5% probability level

0 - 56 - c

3.1.1.B.3. Fruit firmness at harve.st and after storage and colour,

specific gravity, and tissue moisture content at harvest

Firmness. Clear effects of both fruit size and region on fruit

firmness were evident (Table 10). B.C. apples were substantially softer

after 8 1/2 months storage at 1°C. Medium size B.C. apples were as firm

as medium size Quebec apples near harvest time but the B.C. fruit softened

more during the storage period. Likewise, B.C. large fruits softened in

cold storage more rapidly than the comparable Quebec fruit (34% loss of

firmness compared to 27%). Flesh firmness of the fruit shortly after

harvest was found to be an excellent predictor of breakdown (Table 14).

Percent red colour. The Quebec fruit used for this experiment were

more highly colored than the B.C. fruit (Table 11). The 3 size classes

of Quebec fruit were uniformly coloured whereas the smallest B.C. fruits

were less red than the rest of the fruit in the experiment.

Specific gravity. Where there were comparable fruit diameters, B.C.

apples were higher in specific gravity than the Quebec fruit (Table 12).

However, the largest fruits from each location were significantly less

dense than the 2 smaller sizes.

Moisture content. Conversely, flesh moisture content was higher

in the Quebec fruit {Table 12). At both locations flesh moisture

content was higher than peel moisture content but there was no clear

relationship to fruit size. 0 - 57 -

0 / 0 BREAKDOWN 70

60

50- B. C. EL= Edra Lorgf L=Lorge M=Medium S =Small 40- J

30

20-

s 10

I 5.70 6.81 7.27 7.73 8.18 Fl RM NESS (Kg)

Fig. 10 Firmness in kg within 3 weeks of harvest related to Spartan 0 breakdown after 8 1/2 months in storage. - 58 - c

Table 10. Firmness (kg) of Quebec and B.C. Spartan apples of

different sizes (a) within 3 weeks of harvest and

(b) after 8 1/2 months in 1°C storage

Location Size No. examined Firmness (kg) (a) (b) (a) (b)

1 1 Quebec Small 50 25 8.20 a 5.77 a

Quebec Medium 50 25 7.60 b 5.24 b

Quebec Large 50 25 7.29 c 5.34 b

B.C. Medium 50 25 7.64 b 4.97 c

B.C. Large 50 25 6.91 d 4.56 d

B.C. Extra Large 50 25 6.35 e 3.54 e

1 1 Quebec Med. & Large 100 50 7.45 a 5.29 a

B. C. Med. & Large 100 50 7.28 b 4.77 b

1 Quebec Small 50 25 8.20 a 5.77 a 1

Que. & B.C. Medium 100 50 7.62 b 5.13 b Que. & B.c. Large 100 50 7.10 c 4.95 c

, B.c. Extra Large 50 25 6.35 d 3.54 d

1 Mean separation, within columns, by Scheffe's (1950) test performed

at the 5% probability level - 59 -

.c

Table 11. Average surface red colour (%} of the Quebec and B.C.

Spartan apples used in these experiments

Location Fruit size n Percent Surface Red Colour

1 Quebec Small 50 86.1 a

Quebec Medium 50 85.5 a

Quebec Large 50 85.2 a

B.C. Medium 50 69.6 b

B.C. Large so 80.4 a

B.C. Extra Large 50 86.8 a

1 . Mean separation by Scheffe's (1950) test performed at the 5%

probability level - 60 -

Table 12. Specific gravity and percent peel and flesh moisture

content of Quebec and B.C. Spartan apple of various

sizes

Location Fruit Size n Specific % moisture gravity Peel Flesh

1 1 1 Quebec Small 50 .812 be 80.30 a 85.83 a Quebec Medium so .809 cd 79.63 ab 86.05 a Quebec Large 50 .802 d 78.43 e 85.93 a

B.C. Medium 50 .824 a 78.46 e 83~57 e

B.C. Large 50 .818 ab 80.73 a 84.51 b

B.C. Extra Large 50 .803 d 78.42 e 84.44 b

1 1 1 Quebec Med. & Large 100 .806 a 79.03 a 85.99 a

B.C. Med. & Large 100 .821 b 79.60 a 84.04 b

1 1 Quebec Small 50 .812 b1 80.45 a 85.83 a

Que. & B.C. Medium 100 .817 a 80.36 a 84.81 c

Que. & B.C. Large 100 .810 b 79.50 b 85.22 b B.C. Extra Large 50 .803 c 78.42 c 84.44 d

1 Mean separation, within columns, by Scheffe's (1950) test performed

at the 5% probability level c - 61 - c

3.l.l.B.4. Juice acidity and soluble solids content

Juice acidity. Acidity of Quebec apples, reported here as percent

malic acid, was about 20% lower than the B.C. fruit (Table 13). There

was no relationship to fruit size at either location but when the

sizes and locations were combined the larger fruit appeared to have

higher acidity.

Soluble solids. Likewise, juice soluble solids were generally

lower in the Quebec fruits examined (Table 13). At both locations

the smallest fruits exhibited significantly higher soluble solids

than the largest fruits.

3.l.l.C. Discussion ·

. 3.1.1.C.l. Development of breakdown and rots in cold storage

When stored under high humidity conditions (92-94% R.H.), fruits

from both provinces began showing symptoms of breakdown after 6 1/2

months in storage. This is considered to be quite late in the sto­

rage season and is an indication that the Spartan apples harvested

in 1974 in the Okanagan Valley were not particularly susceptible to

breakdown. Nonetheless, using inductive conditions, breakdown did

occur in the experimental lots. This clearly supports the contention

of Porritt and Meheriuk (1973) that high humidity enhances the develop­

ment of the disorder. Even in this favorable year the B.C. apples 0 were noticeably more susceptible to breakdown than the Quebec fruit - 62 - c

Table 13. Juice acidity (% malic acid) and percent soluble

solids of B.C. and Quebec Spartan apples of various

sizes measured shortly after harvest

Location Fruit Size n % Malic Acid % Soluble Solids

1 Quebec Small 50 13.27 ab .

Quebec Medium 50 .443 b 11.98 d

Quebec Large 50 .438 b 12.65 c

B.C. Medium 50 .564 a 13.54 a

B.C. Large 50 .552 ab 13.33 ab

B.C. Extra Large 50 .558 ab 12.94 be

Quebec Med. & Large 100

B.C. Med. & Large 100 .558 a 13.44 a

1 1 Quebec Small 50 .454 c 13.27 a

Que. & B.C. Medium 100 .503 b 12.76 b

Que. & B.C. Large 100 .495 b 12.98 a

B.C. Extra Large 50 .558 a 12.94 ab

1 Mean separation within columns, by Scheffe's (1950) test performed

at the 5% probability level.

0 - 63 - c

(Table 3 and Fig. 8}. Apples of greater diameter were more susceptible

to breakdown. This confirms observations by other workers with the

Spartan cultivar (Mason et al. 1973; Lidster et al. 1975) and other

apple cultivars such as Cox's Orange Pippin (Martin, 1954), Jonathan

(Trout et al. 1940; Chace, 1962; Martin et al. 1965), Northern Spy

(Bernstein and Marshall, 1942) and Delicious (Hall and Cellier,

1966). While the greater susceptibility of B.C. medium and large

apples to breakdown parallels that of Quebec medium and large fruits

it increases sharply in the case of the extra large fruits (i.e. when

exceeding 7 cm in diameter as seen in Fig. 8}. This agrees with the

findings of Lidster et al. (1975) that to minimize Spartan breakdown

incidence, the optimum diameter is 5.8 cm.

This apparent relationship between breakdown susceptibility and

fruit size, however, requires further discussion. The segregation of

individual fruits on the basis of radial diameter as done in this study

was considered to be valid because: 1) this is the grading technique

used by the apple industry across Canada;- and 2) radial diameter was

considered more likely to reflect similar growing conditions, particularly

tree nutrition, than a segregation technique based upon fruit weight.

The validity of this assumption, however, may be questioned when

the data for percent breakdown are plotted against mean fruit weight

for the six categories of fruit (Fig. 9). Plotted in this manner, the c regional differences in breakdown susceptibility are clearly diminished - 64 -

by the relationship between breakdown and fruit weight. The B.C. fruit

were considerably heavier than Quebec Spartan's of the same diameter.

B.C. medium and large apples averaged 122.2 and 177.7 g, respectively compared to 98.8 and 117.8 g for the Quebec fruit. This difference

is due to a higher specific gravity (Table 12) and to the more elongated

shape of western-grown apples. This latter is normally attributed to

cooler temperatures early in the growing season (Sullivan, 1965).

Such conditions apparently encourage cell elongation and/or cell divi­ sion near the calyx end of the fruit. The hormonal basis for this

can be deduced from the effectiveness of the gibberellin-cytokinin

spray mixtures now used commercially to elongate eastern-grown apples

(l-1illiams and Stably • 1969; Unrath, 1974 and 1978).

In general, the factors which encourage the development of break­

down in storage appear also responsible for the development of decay

in storage (Edney, 1973). Factors which may contribute to increasing

breakdown and mold development in storage according .to Edney (1973) are excessively high levels of K in leaves and fruits. a high K to Ca

ratio in fruits, low frtiit Ca content and low levels of fruit anthocya­ nins. Montgomery and Wilkinson (1962) concluded that a heavy crop load could cause a higher reduction of rotting in storage·and was a

greater determining factor than manurial treatments. Nonetheless,

they indicated that high N and K fertilisation and clean cultivation

as opposed to sward caused considerably more rotting of Cox's Orange c Pippin apples. On the other hand high P soil application in absence - 65 - c

of N decreased the incidence of rotting in storage.

Some of these factors may have played a role in the development

of breakdown and rots in this study. Quebec apples developed fewer

rots and less breakdown and we might expect them to be richer in

phenolics, especially chlorogenic and quinic acidst and contain most

likely higher levels of protein. These characteristics were not

examined in the present study but would be interesting topics for

further research.

3.l.l.C.2. Fruit mineral content

Total nitrogen. A number of workers have stated that large-sized apples are more susceptible to storage disorders (Faust et at. 1969; Lidster 1975; Smock and Neubert 1950; Link 1974; Shear 1975; Bramlage

et al. 1974; Mason et at. 1973; Martin 1954). The present work

supports this relationship (Table 3) but we were unable to associate

fruit N with fruit size in Spartan apples since no significant diffe­ rences were found between Quebec and B.C. 'Spartan' apples for both peel and flesh N content (Table 4). Moreover, the total N content

of the fruit showed no significant relationship to breakdown (Table 14).

Likewise Lidster et at. (1975) found no relationship between amino N

and breakdown incidence in Spartan apple.

Magnesium. Among the various elements which were found to play 0 a role in bitter pit development, Brooks and Fisher (1918) found Mg to be the most important. Sharples (1971), Wirth et al. (1970) and - 66 - c

Das (1971) provided further evidence that excessive Mg could provoke

bitter pit development.

Concerning Spartan breakdown, the results indicate that peel Mg

was one of the best predictors of breakdown (Fig. 11 and Table 14) with 2 a r of .930. Flesh Mg was also a good predictor of breakdown (Fig. 11

and Table 14) with a r 2 of .826. . These results do not agree with t h ose

of Lidster et at. (1975) who found that flesh Mg was not a good

predictor of Spartan breakdown although these workers analyzed only

the flesh of B.C.-grown Spartan apples.

Interestingly, peel Mg increased with increasing fruit size whereas

flesh Mg did not (Table 5). Furthermore, B.C. apples had higher peel

Y~ which may relate to the fact that the B.C. apples developed more

at the calyx end. Redmond (1975) found that Mg accumulated at the

calyx end of apples where lenticels are more numerous. Shear (1975)

reported that excessive transpiration rates could eventually induce

bitter pit and corking disorders. Similarly Gerard and Hipp (1968)

showed that vapor pressure deficit above 14 to 15 mm Hg induced

blossom-end rot of tomatoes. One could therefore postulate that

apples grown under the high transpiration conditions of the dry and

sunny B.C. interior accumulate more Mg in the peel. Mg is very mobile

in plants (Epstein, 1972) and should be translocated more rapidly

and accumulate more in fruits or plant parts where transpiration is

high. Humid conditions prevailing in Quebec would favour the opposite

c situation. The fact that B.C. apples were higher in peel Mg than the - 67 - c

Quebec ones may also be partly explained by the more active photo­

synthesis of the apple trees growing in the Okanagan Valley where solar

radiation is much higher than in Quebec. During the early part of the

growing season apple fruits develop chlorophyll, which of course contains

Mg in the center of its porphyrin ring, and the amount of chlorophyll

may relate to location.

Leaching of elements such as Mg and K from leaves .and fruits has

been observed (Epstein, 1972; Tukey, 1970) and may also partially

explain why the B.C. apples have high levels of Mg and K. First the

amount of water used in over-tree irrigation in the Okanagan Valley

apple trees was much less than the rain water which falls seasonally

in Quebec. MOreover, the irrigation water contains dissolved salts

and therefore does not lend itself to leaching as much as does rain

water.

As seen in Table 15, Quebec soils may contain fairly high levels

of Mg. However, they are generally low in available Mg to apple

trees (Heeney and Hill, 1960; Granger, 1974). An increase in that

element by the regular Epsom salt orchards sprays is important for

increasing the level of Ca in the Quebec or B.C. grown fruit. In

both provinces this treatment is recommended and may help to reduce

the Spartan breakdown development because according to Shear (1974)

increasing Mg supply from a deficient to an adequate level can increase

Ca uptake whereas a further increase will reduce the Ca uptake. 0

23 23

down. down.

Break-

* *

22 22

.901 .901

(fr.) (fr.)

C2H4 C2H4

0 0

* *

21 21

(Wt.) (Wt.)

CzH4 CzH4

-.849 -.849

-.658 -.658

2 2

* *

* *

20 20

*"' *"'

co

(fr.) (fr.)

.967 .967

.873 .873

-,883 -,883

2 2

19 19

co

.737 .737

(lit.)· (lit.)·

-.778 -.778

-.659 -.659

form form

18 18

(F) (F)

.603 .603

,354 ,354

Moist. Moist.

-.576 -.576 -.733

-.338 -.338

-.499 -.499

matrix matrix

in in

** **

17 17

.574 .574

.250 .250

.940 .940

(P) (P)

-.676 -.676

. .

-.542 -.542

-.645 -.645

Moist. Moist.

** **

** **

711 711

• •

.475 .475

.683 .683

16 16

-.5oo -.5oo

-.957 -.957

-.934 -.934

-.800 -.800

.presented .presented

M.ac:id M.ac:id

and and

15 15

,154 ,154

.115 .115

.650 .650

.202 .202

.019 .019

s.s. s.s.

-.702 -.702 -.599 -.599

-.218 -.218

* *

* *

* *

,.~·---

** **

** **

studied studied

.441 .441

.387 .387

.836 .836

.871 .871

.045 .045

-.945 -.945

-.924 -.924

-.559 -.559

-.909 -.909

harvest harvest

l"irm.at l"irm.at

6 6

• •

13 13 14

.354 .354

.498 .498

.605 .605

.126 .126

factors factors

n n

-.458 -.458

-.242 -.242

-.438 -.438

-.074 -.074

-.271 -.271

-.607 -.607

Crar, Crar,

Spec:, Spec:,

• •

all all

% %

,018 ,018

.160 .160

.006 .006

.762 .762

.194 .194

.853 .853

.579 .579

.039 .039

red red

12 12

,841) ,841)

-.166 -.166

-.576 -.576

-.586 -.586

• •

* *

2 2

* *

* *

* *

** **

. .

(r (r

relating relating

.934 .934

.903 .903

.441 .441

.845 .845

.871 .871

.048 .048

ll ll

p p

(F) (F)

-.757 -.757

-.763 -.763

-.767 -.767

-.863 -.863

-.865 -.865

-.231 -.231

(1'_) (1'_)

.917 .917

* *

"' "'

* *

** **

** **

,607 ,607

'771 '771

.737 .737

.976 .976

,604 ,604

.934 .934

is is

10 10

l' l'

(P) (P)

-.851 -.851

-.664 -.664

-.908 -.908

-.400 -.400

-.843 -.843

-.676 -.676

-.soo -.soo

** **

values values

* *

* *

* *

"' "'

** **

** **

** **

799 799

9 9

lt lt

(F) (F)

,829 ,829

.960 .960

,834 ,834

.912 .912

.380 .380

.s63 .s63

,01 ,01

,961 ,961

-.616 -.616

-.834 -.834

-. -.

-.755 -.755

-.040 -.040

-.828 -.828

-.213 -.213

' '

• •

' '

* *

* *

* *

P P

*" *"

** **

"'* "'*

*" *"

.854 .854

.786 .786

.973 .973

.938 .938

.715 .715 .256 .256

.942 .942

,537 ,537

.967 .967

8 8

at at

K K

(P) (P)

-.676 -.676

-.893 -.893

-.861 -.861

-,467 -,467

-.801 -.801

Correlation Correlation

* *

* *

* *

** **

** **

7 7

,621 ,621

.909 .909

.819 .819

,604 ,604

.815 .815

.256 .256 (1") (1")

.703 .703

.193 .193

.954 .954

.889 .889

14. 14.

value value

-.781 -.781 -.745

-.646 -.646

-.731 -.731

-.431 -.431

-.459 -.459

-.343 -.343

P P

• •

* *

• •

• •

** ** ** **

** **

** ** •• ••

962 962

Table Table

Mg Mg Mg

(l') (l')

,800 ,800

.ass .ass

.970 .970

.940 .940

,881 ,881

•. •. .84' .84'

.980 .980

.307 .307

.899 .899

-.906 -.906

-.723 -.723

-.636 -.636

-.095 -.095

-.714 -.714

-.933 -.933 -.012 -.012

.657); .657);

* *

* *

* *

• •

• •

** **

** **

•• ••

** **

706 706

794 794

726 726

773 773

2 2

,862 ,862

,687 ,687

• •

.306 .306

5 5 6

Ca Ca

(F) (F)

.• .•

(P

-.ass -.ass -,859 -,859

-.OlS -.OlS

-. -. -.946 -.946

-.904 -.904

-.930 -.930 -.861 -.861

-.940 -.940

-.797 -.797

-.308 -.308 -. -.

* *

* * * *

* *

•• ••

.811 .811

ea ea

(P) (P)

.847 .847

.227 .227

.946 .946

.186 .186

.765 .765

.524 .524 .722

.559 .559

.505 .505

-.649 -.649

-.831 -.831

-.725 -.725

-.857 -.857

-.788 -.788

-.sso -.sso

-.622 -.622

-,697 -,697

-.807 -.807

-.044 -.044

-.848 -.848

is is

* *

363 363

3 3 4

N N

(F) (F)

,220 ,220

• •

.6SO .6SO

.388 .388

.082 .082

.460 .460

.439 .439

.729 .729

.511 .511

.031 .031

-.411 -.411

-.506 -.506

.OS .OS

-.189 -.189

-.048 -.048

-.461 -.461

-.741 -.741

-.349 -.349

-.036 -.036

-.SOS -.SOS

-.061 -.061

• •

0 0

P P

2 2

590 590

N. N.

(P) (P)

,093 ,093

.032 .032

.591 .591

.176 .176 ,214 ,214

.362 .362

.625 .625

.449 .449

.532 .532

.213 .213

,255 ,255

.226 .226

" "

-.380 -.380

-.030 -.030

-. -. -.480 -.480

-.087 -.087

-.239 -.239

-.215 -.215

-.640 -.640

at at

* *

* *

* *

** **

** **

** **

974 974

774 774

. .

.251 .251

• •

.856 .856

.8S2 .8S2

.804 .804

• •

.247 .247

.87! .87! .890 .890 ,037 ,037

.620 .620

.802 .802

rots rots .937 .937

.9M .9M

.342 .342

1 1

.786 .786

-.629 -.629

value value

% %

1 1

23 23

1~ 1~

22 22

5-,801-.282 5-,801-.282

2 2

7 7 8 8

• •

4 4

9 9

21-.967 21-.967

zo zo

16 16

3 3 11 11

lS lS

19 19

6 6 10 10

14-.872 14-.872

18-.611 18-.611

12-.018 12-.018 13 13 Table 15. Soil analysis report (mean of 8 samples)

1 1 1 Location O.M. pH Salts Available Elant nutrients (Lb/2M} and rating (L2 M2 H) (Mmhos/cm) Nitrates PhosEhorus Potassium Calcium Magnesium p N03-N K ea Mg

Summerland 2.725 7.1 .390 30.5 H 98 M 518.5 H 4018 L 595 H

Fresniere 7.675 6.1 .455 16.5 L 13 L 274.5 L 7332 M 1000 H

"'::> 1 I Symbols: O.M. = organic matter; Mmhos/cm = millimhos per centimetre; LB./2M = pounds per million pounds or pounds per acre six inches (assuming 2 million pounds per acre 6"); H • high; M= medium;

L = low

0 0 ~ 70 - c

Bangerth (1974) states that Mg and K are the only ions that

antagonize Ca and aggravate bitter pit development. This relation-

ship probably also applies to Spartan breakdown and helps explain why

B.C. apples with a high Mg content have a stronger tendancy to break-

down. The findings of Mason and McDougald (1974) that Mg ana K increase

in Spartan apples low in Ca support this conclusion.

2 Potassium. Even though peel K had a r value of .728 (above the

cut off point of .66 for P = .05), it was considered invalid as a pre-

dictor for Spartan breakdown since the distribution of the observed

peel K values did not fit a single straight line pattern when plotted

against % breakdown as per Fig. 12. Flesh K was found to be a reliable

predictor of Spartan breakdown with a r 2 value of .922 (Fig. 12 and

Table 14). This parallels very nicely the results of Lidster et at.

(1975). They found that flesh K along with flesh Ca and flesh B

were good predictors of Spartan breakdown. Their flesh K levels

ranged from 1,080 to 1,240 ppm on a fresh weight basis and my results

when expressed on the same basis were very similar, ranging from

1,019 to 1,196 ppm for comparable B.C. Spartan apples (Table 16).

Since the Quebec apples have flesh K contents ranging from 787 to

860 ppm on a fresh weight basis they would be expected to be less

prone to breakdown development because, according to Lidster et at.

(1975), flesh K of Spartan apples should be less than 883 ppm to

minimize Spartan breakdown. - 71 -

c I % BREAKDOWN \70

lao

J5o

]40

[so

j20

~~.5~.. 5-.. o .. -----l-.. -. -----r·.. ------~-.------.7·--o-----~-s.oro------f8 1?0 600 1650 700 L 5. . -----1 PE_EL MG. (ppm drY--wt)

12oo /225 1250 1275 /300 /325 !350 • •fFLESH .. MG.(f)pm drY wt)

Fig.ll Spartan breakdown after 8 1/2 months in storage as related to peel and flesh magnesium. - 72 - c

An important factor which may explain why B.C. apples have such

high K levels is the very high content of available K in Okanagan Valley

soils (Swales, 1971) compared to the low levels observed in Quebec

orchards soils (Granger, 1974; Table 15). Moreover, being an extremely

mobile element (Epstein, 1972; Meyer and Anderson, 1952; Redmond, 1975),

K moves freely with the transpiration stream during the growing season.

Thus, the discussion with regard to Mg is also applicable here. While

the high transpiration rate may partially explain why B.C. apples have

higher K than the Quebec ones, other metabolism-related explanations

may be more appropriate. The largest B.C. apples would be expected to

transpire less than the smallest ones (Smock and Neubert, 1950) since

they have a smaller surface to volume ratio yet the flesh K levels are

highest in the largest fruits (Table 6).

Lau and Looney (1978) reported that Golden Delicious apples grown

in the Okanagan Valley had nearly 20% less K than the Golden Delicious

apples grown in the warmer and dryer Washington state. Carbohydrate metabolism is known to be influenced by K+ ion (Meyer and Anderson,

1952). This may explain why the B.c. apples which contained significantly more K also contained substantially more soluble solids and acids

(Table 6 and Table 13). This association has also been reported for

apples by Wilkinson (1958) and for grapes by Wood and Looney (1977). ·

Calcium. The level of Ca in the Fresniere soil was high compared

to that of Summerland (Table 15 ). Correspondingly, both peel and

c flesh of the Quebec-grown Spartan apples tended to be higher in Ca - 73 - c

content than those from B.C. (Table 7) but these differences were not

as great as expected. Previous workers (Mason and MacDougald, 1974;

Mason et al. 1975; Lidster et al. 1975) have associated Ca levels

more directly to the incidence of Spartan breakdown. Nonetheless,

Table 14 shows significant negative correlations between both peel

and flesh Ca content and the incidence of Spartan breakdown (P • .05

and P • .01, respectively). However the interrelationship between

Ca++ and the other predominant cations appears to be more important

in explaining Spartan breakdown in the present study. Calculated on a

molar basis, the sum of K + Mg divided by Ca content shows a strong

positive relationship to breakdown (Tables 17 and 18). Likewise K +

Mg + P divided by Ca relate positively to susceptibility to breakdown.

When taken individually Mg, K and P show the same relationship (ibidem).

This indicates that a proper balance of all these elements is important

(Garman and Mathis, 1956).

Researchers (Millikan, 1971; Looney, 1977) have shown that peel

tissues are higher in Ca than flesh tissues. The present results

confirm that finding. This difference is equally apparent in B.C.

and Quebec apples. The situation is different, as will be seen

shortly, for P.

If the observations with Golden Delicious in Holland (Tromp,

1975) can be applied to the Spartan cultivars in Canada, one would c predict lower fruit Ca in B.C. fruits because of higher summertime temperatures. The small difference observed between the 2 locations - 74 - c suggests either little climatic difference or that Tramp's generali­

zation is not applicable to this situation~

As previously mentioned Mg and K were found by Bangerth (1974) to

antagonize the function of Ca and therefore amplify the incidence of

breakdown whenever they are present in excessive amounts in fruit

tissues. Weeks et al. (1965) arrive at a similar conclusion. Table

5 and 6 show that both peel and flesh Mg and K content of the B.C.

Spartan apples are significantly higher than that'o£ Quebec. Therefore,

in the B.C. fruit both Mg and K ions were more likely to antagonize

the function of Ca than in the Quebec fruit.

Bramlage et al. (1974) stated that for Baldwin apples grown

in Massachusetts the critical level for peel Ca was 700 ppm dry

wt. The data from my experiment indicate that the same statement could

apply to Spartan apples. In fact, the only fruit which had a peel

Ca level higher than 700 ppm were the small apples from Quebec (Fig.

13). These small apples also developed less than 10% breakdown after

8 1/2 months of storage (Fig. 8) and they were the only ones with a

Ca content significantly higher than that of all others {Table 7).

Lidster et aZ.. (1975) recommended that for complete freedom from

Spartan breakdown flesh Ca levels should not be lower than 42 ppm fr.wt.

or approximately 300 ppm dry wt. None of the apples in this study

approached that level (Tables 7 and 16). The level suggested by

Lidster et al. (1975) may have related to a year with abnormally high 0 - 75 -

c %BREAKDOWN EL 70

60

50

40

30

, B.C. 20 El = Extra largej l= large M= Medium J. S Small 10 s

0~----~----~-----.-----.~---.-----. 5000 5500 6000 6500 7000 7500 8000 • •) FLESH K (pp mdr~ wt)

Fig. 12 Spartan breakdown after 8 1/2 months in storage as related c to peel and flesh potassiUm. - 76 - c !% BREAKDOWN [70

{40

l8.c, ;EL,;, Extra largj j20 l= large M= Medium . \0J S =Small

i10

f650 f7oo faoo ------f Peel Ca (ppm dry Wt)

1150 1 200 12~0 j3oo •• --~-•~rFiesh Ca (ppm dry wt)

.. -·-··-~---..-... -,. -~~--- ... ---...... -----__,...... - -·-----.-----~-·~·~---~~~~ ---·.. ~~ ... ·- -~~ -~ ·-· ---

Fig. 13 Spartan breakdown after 8 1/2 months in storage as related c to peel and flesh calcium. - 77 - c

flesh Ca levels since Looney (1977) stated that 225 ppm (fr. wt.)

was a more normal level below which Spartan breakdown development may

be severe. On that basis only the small apples from Quebec were

likely to have a minimum of breakdown and that agrees with the

Bramlage et al. {1974) findings.

A large number of ratios relating Ca to other ions and to Spartan

breakdown could have been studied. The ones listed in Table 16 are

the most important according to this literature search and involved K,

Mg and P. Strikingly enough, when expressed on a molar basis all

ratios increased as fruit size increased from small to extra-large.

These increases parallel the increased susceptibility of the various

apple sizes to Spartan breakdown. Stebbins (1972), reporting work of

Kepka and Stiles at Rutgers N.J., mentions that Cork spot and breakdown

were induced in Golden Delicious apples from apple trees with Malling 9

roots grown in sand and fed with Ca deficient solutions. According

to these workers, high ratios of K + Mg + P to Ca, Mg to Ca or K to

Ca in the nutrient solution induced cork spot and bitter pit.

Both peel and flesh ratios of K + Mg + P to Ca were positively correlated to breakdown (Table 18). The flesh ratio exhibited a higher

degree (P • 0.01) of correlation than the peel. Other ratios seen in

this table such as Mg to Ca, K to Ca, Mg + K to Ca and P to Ca were

also well correlated to Spartan breakdown at P • .01 or P • .05. Sharples

(1967) has also found that the incidence of water core was correlated

0 with both K to Ca and Mg to Ca ratios. - 78 - c

Table 16. Nitrogen, calcium, magnesium, potassium and phospho-

rus content of peel and flesh of apples of various

sizes from Quebec and BritisH Columbia. Each mean, expressed as ppm fresh weight, represents 50 apples

Category Total N ea Mg K p (% f.wt)

Q s p .375 139.17 126.34 1015.24 108.69

QMP .368 128.09 125.32 1013.19 102.99

QLP .389 115.59 128.09 1145.12 118.54

Q SF .132 32.32 32.34 787.52 71.61

QMF .120 30.04 31.07 778.11 70.19 QLF .142 27.62 32.12 859.93 82.01

BC MP .404 135.29 155.97 1649.20 238.15

BC L P .407 128.63 160.43 1529.97 242.13 BC EL P .425 126.6 188.04 1721.84 246.96 BC M F .147 31.15 37.72 1109.76 106.72

BC L F .138 29.23 35.8 1019.18 108.48 BC EL F .158 27.37 39.01 1196.48 118.6

Legend: Q • Quebec; BC = British Columbia; S • Small; M = Medium; L • Large; EL = Extra Large; P = Peel; F • Flesh; f.wt = fresh weight c 2.86

4.79

2.98 5.59

3.83 4.42

Flesh

P/Ca

0

•

2.27

2.52 1.32 1.01 2.43

1.07

Peel

2

Quebec

from

workers

25.01

26.25 36.57

44.81 31.90

35.75

Flesh

sizes

K/Ca

previous

various by

7.49

8.11

Peel

10.15

13.94

12.16

12.50

of

important

apples

1.64 2.01

1.68 2.34

1.99

Flesh

Spartan

Mg/Ca

of considered

2.44

1.49 1.61 1.82 1.91 2.05

Peel 1.90

are

1975

tissues

aZ.

ratios

et

29.52

42.98 Flesh 30.92 37.65

42.55

52.75

P/Ca

flesh

+

and

Mg

Lidster

+

9.98

particular

K Peel

peel

13.31

10.80

16.67 16.65

18.90

1975;

in

1

These

(ppm/m.wt)

26.64 27.92

Flesh

33.82

37.76 47.16

38.56

ratios

B.C.

Redmond,

Mg/Ca

basis

Ion

and

+

K

1956;

17.

8.98 9.73

Peel

molar

11.98 14.39

16.39

14.21

a

on

Mathis,

Table

and

and

8)

(68.4)

(27.8)

(38.2)

(8. (14.6)

(23.1)

Garman

Calculated

0

%breakdown

Category

QS

QM

QL

2

BCM

BCL BCEL 1

.....

:;!'\ ______...-'

Table 18. Correlation values of the most important ion ratios and Spartan breakdown

~

1 2 3 4 s 6 7., 8 9 10 Mg (P) + K (P) Mg (F) + K (F) !U!L K (F) ~) Mg (F) K (P) + Mg (P) + P (P) K (F) + Mg (F! + P (F) P(P) ~ Ca (P) Ca (F) ea (P) Ca (F) ea (P) ea (F) ea (P) ea (F ea (P) ea (F:

•· .9148:* .9664** .903~ .9660** .99n .9796** .905~ .96M .9305* .951<

~ vQlue at P • .05 * is .811 n ~ 6

~ value at P • .01 ** is .917 "

0 0. - 81 - c

Phosphorus. While several authors (Martin et aZ. 1965; Letham,

1969; Tiller et al. 1959; Perring, 1968) have reported that increased

levels of P usually improve resistance to breakdown, the opposite was

found, at least with flesh P, in my experiment (Table 8 and Fig. 14).

On the other hand, Garman and Mathis (1956) found higher levels of P

in apple tissues affected by 'Baldwin spot' compared to healthy tissues.

The observed peel P values could not be described by a straight line and 2 . 2 their r of .593 was lower than the calculated r threshold (P = .05} 2 of .657 (Table 14). Flesh P however with a r of .873 (significant

at P = .01) was an acceptable predictor of breakdown. Since I had to

encourage breakdown development during the storage season of 1974-75 by holding the fruit in a high humidity .environment, it is perhaps more correct to say that flesh phosphorus was a predictor for induced

Spartan breakdown. Lidster et al. (1975) failed to find that flesh

P was a good predictor of naturally occurring Spartan breakdown.

Quinlan and Preston (1968) found that with the fruits of

apples, large fruit size was due to an increase in cell number, rather

than an increase in cell volume. From these findings one might expect

that the B.C. Spartan apples had more cells than the Quebec ones. In

fact, the B.C. apples were denser (Table 12) and contained more P than

the Quebec apples (Table 8 and Fig. 13). This may be explained by

noting that P is an important constituent of cell -alls (Meyer and

Anderson 1952) and that there is a fairly large percentage of P in 0 the cytoplasm in the form of phospholipids, nucleic acids, coenzymes, - 82 - c

etc. Strikingly enough, peel P content of the B.C. Spartan apples was

almost double that of the flesh P content whereas this difference is

hardly noticeable in the Quebec apples (Table 8 and Fig. 13). If, as

just mentioned the P content of a tissue corresponds to its cell

number, the peel or flesh of B.C. •spartan' apples should then have

a much higher number of cells than the peel or flesh of the Quebec

Spartan apples. And, if these tissues contain more cells they should

have more P, more minerals, more solids and therefore, less constitutive

water. This suggestion is at least partly supported by my data since

while no significant difference was found in the peel moisture content

of apples from both provinces, the flesh moisture content of the B.C.

fruit was significantly smaller (Table 12). Other support for this

suggestion is found in tables 5, 6, 7, 8 and 9 which show that the

B.C. apples contained more peel and flesh minerals, except Ca and Zn which

repr~sent only a very small proportion of the total minerals of an

apple (Smock and Neubert, 1950). Moreover, the B.C. apples are denser

(Table 12) and they contained more solids (Table 13). A complementary

discussion concerning the involvement of P in the respiration of the

fruits is contained in Chapter 3.1.2.

Zinc. Despite of the fact that we obtained only partial information

on the peel Zn levels of Quebec apples, at least one fact was generated

by our Zn analysis. The flesh of the B.C. apples had significantly

lower levels of this element (Table 9). Zn deficiency symptoms are 0 almost never observed in Quebec orchards (Granger, 1975) whereas - 83 - c

rosetting, chlorotic mottling of the leaves and dead spur disorder

of apple trees are frequently seen in B.C. orchards (Swales, 1971 and

1976).

Cultural and·environmental factors

Except for Ca and Zn the B.C. apples contained significantly more

minerals than did Spartan apples grown in Quebec (Tables 5, 6, 7, 8

and 9). This may be partially explained by the warmer and dryer clima-

tic conditions of the Okanagan Valley. However, the incidence of

breakdown was considerably higher in the B.C. fruit in 1974. For the

year 1974, from May to September inclusively, Summerland, B.C. had

1461 hours of sunshine while Fresniere, Quebec had only 1064 hours • • Fisher (1972) who compiled the meteorological data of the apple

growing areas of Canada for the past 50 years shows that Summerland

has an over-all average of 2054 degree days (using a threshold of 50 0 F)

while Oka (close to Fresniere) averages 1064 degree days on the same

basis. Moreover the soil temperature at a depth of 20 centimeters, where many of the feeder roots of an apple tree are located, was

warmer at Summerland than at Ste-Anne-de-Bellevue (close to Fresniere)

0 by an average of 4.5 to 5.~ C from May to September 1974 inclusively.

The monthly difference in temperature ranged from 1.8·to 5.4°C and

the most striking differences occured in May and September (Table 19).

With respect to sunlight exposure lleinicke (1966) concluded that

well exposed Mcintosh apples in the Okanagan Valley were less firm

0 than heavily shaded ones. Shear (1975) indicates that light intensity - 84 - c %BREAKDOWN EL 70

60

50

40

30

B. C. EL= Extr.a Largej 20 L =Large M= Medium 0J S =Small

10

0~~--~------~------r----~.------.------. 400 600 800 1000 1200 1400 1600 • • FLESH P (pp m dry wt)

Fig. 14 Spartan breakdown after 8 1/2 months in storage related to flesh phosphorus. - 85 -

.C

has been related to the incidence and severity of Ca related disor­

ders. Chong and Taper (1971) have also stated that solar radiation

has a positive effect on seasonal concentration of sorbitol and

related carbohydrates in apple leaves.

In view of the rather large differences in the temperature and

light environment between the B.C. and Quebec orchards it is perhaps

remarkable that the Spartan apples from the two locations were as

similar as they were. For example, the relationship of fruit weight

to breakdown incidence (Fig. 9) appears to be generally the same at

both locations. Only the magnitude was different. A similar state­

ment could be made about the relationship of fruit firmness at harvest

to breakdown (Fig. 10) and other mineral content predictors of

breakdown.

While the fruit ash and K levels increase considerably during

the growing season, fruit Ca and P apparently increase very little

(Fig. 15). Since the gap between Ca level and that of other minerals

except P becomes greater as the season progresses a practical way

of diminishing this gap would be desirable. Recent experiments

conducted by Unrath (1972) in North Carolina with overtree irrigation

to cool Red Delicious apples may apply to the Spartan problem.

This treatment had made Red Delicious apples ripen one week earlier

than normal and improved their keeping quality by reducing cork

spot and bitter pit development in storage. By reducing leaf trans­

piration rate he probably slowed the movement of Ca from fruits to - 86 - c

Table 19. Mean 1974 soil temperature ( 0 C) at a 20 cm depth in 1 Quebec and B.C. near the experimental orchards

Summer land

May June July August Sept.

Average 13.05 19.13 21.4 23.15 20.45

Ste-Anne-de-Bellevue (close to Fresniere)

May June July August Sept.

Average 8.1 15.73 19.48 18.42 13.51

MOnthly difference

4.95 3.40 2.02 4.73 7.94

overall average 4.6 difference

1 from Anon. 1974 - 87 -

leaves.

Another cultural practice which might narrow the gap between the Ca level and that of other elements such as K and Mg in the fruit would be to simply avoid picking Spartan apples too late. Mr Denys Roy and Mr Adrien Tougas, who have produced fairly large quantities of

Spartan apples at Frelighsburg, Que., came to the conclusion that they had to pick their Spartan apples early to avoid breakdown in cold storage. On the other hand Lidster and Porritt (1978) found that a delay of a few days at 21 0 C prior to storage irrespective of the picking date reduced considerably the incidence of breakdown of

Spartan apples. They suggested that water loss or loss of volatiles could improve fruit resistance to breakdown. Garman and Mathis (1956) recommended choosing the correct picking date as one of the measures to prevent the occurence of Baldwin spot in Connecticut. Mr Benjamin

W. Drew (unpublished, 1976) who harvested from his orchards in Vermont and Massachussetts impressive amounts of eastern-grown Spartan apples over a number of years pointed out that his secret for good keeping quality with this cultivar was to avoid picking the fruit too late.

Since the large B.C. apples are more susceptible to breakdown it would seem advisable for apple growers of the Okanagan Valley to refrain from overfertilizing their Spartan trees with N. Reducing N levels is also recommended by Stebbins (1972) for reducing bitter pit and Anjou cork. All cultural practices which tend to increase the level of N in apples such as pruning, soil cultivation, fruit - 88 - c

:Cl)!.... \5 /3:0 jfE 10 iN 12.5 !a: ' !w·a.. :Cl) :2.0 l:i!! j !.et ·a:;e, !1.5

)1.0

lea : : lP. fAugust fseptember

Fig. 15 Changes in the total ash, potassium, calcium and phosphorus

contents of Stayman Winesap apples during the growing season

on an absolute basis (From Smock and Neubert, 1950, p.69). - 89 -

thinning and heavy mulching should be executed with care.

Lidster et aZ. (1975) in their statistical profile of Spartan breakdown susceptibility ,showed that fruits with a rather low level of soluble solids, i.e. below 11.9%, showed less tendancy to develop breakdown in storage. My findings confirm this association since the very small apples from Quebec were practically free of breakdown and contained much lower soluble solids (Table 13). However, it is difficult to imagine thab soluble solids levels could be controlled as a practical way of reducing breakdown incidence.

Controlling the moisture content of apples is not an easy matter.

As indicated by Stebbins (1972), moisture stress has often been implicated in increasing the incidence of bitter pit and should be avoided. On the other hand, eliminating all moisture stress may lead to big apples with poor storage quality. Moisture stress may relate to the leaf-fruit ratio but an attempt to control this ratio by summer pruning Spartan apples has not been reported. Even summer, pruning can be an invigorating process. In trials conducted at

Frelighsburg, Quebec, summer pruning did not give Mcintosh trees the desired leaf-fruit ratio for good fruit quality. They tended to balance themselves by producing a rather lush vegetative growth after they were pruned. This practice did not improve fruit quality (Granger

1972, unpublished). However the recent of Jackson et at.

(1976) may be far more effective. These workers applied chemical - 90 - c

pruners to James Grieve apple trees and by eliminating all possible

regrowth they obtained a significant control of bitter pit. The same

approach might succeed with Spartan apple trees. Control of the

leaf-fruit ratio would probably also improve red colour development by

exposing the fruits to more sunlight. Under the climatic conditions

wnich prevail in eastern North America, a low leaf/fruit ratio has been

shown to reduce the incidence of breakdown in storage (Knowlton and

Hoffman, 1930). A reduction in leaf number and area should result

in reduced mineral accumulation in the fruit and perhaps also reduce

its specific gravity. Since reducing the number of leaves of an apple

tree also changes its C/N ratio this practice may reduce titratable

acidity (Eaves et at. 1964). As an indirect consequence of this

practice the K/N ratio of the fruit may be lowered and in turn,

reduced K levels may reduce acidity (Wilkinson 1958; Wood and Looney,

1977).

Since, according to Bangerth (1974), Mg and K are important ions

antagonizing the function of Ca, at least in the development of bitter

pit, special attention should be paid to these two elements in the

'management of Spartan orchard soils. Most soils of the Okanagan

Valley have naturally high levels of K and many clay soils in B.C.

contain high levels of Mg (Swales, 1971; Mason, 1966). Many orchard

soils of eastern Canada and eastern U.S.A. are also rather high in . K and Mg. However Mg is not usually readily available to apple trees.

Therefore, while separate applications of potash (KCl, K , etc.) 2so4 - 91 -

may deteriorate the keeping quality of apple fruits and induce Mg

deficiency problems, the addition of a salt combining both K and Mg

in the form of sulphate of potash-magnesia has given beneficial res­

ponses in terms of improved fruit quality and is recommended in

New York, New England, Ontario, Quebec and Nova Scotia.

In order to improve the level of Ca in apple tissues the best

technique presently known was developed at Biglerville, Pennsylvania,

and involves applying 6 to 8 cover sprays of calcium chloride at 3 lbs

per acre. Treating with three sprays of calcium nitrate or at two

week intervals at the rate of 5 lbs/100 gallons of water with a

wetting agent such as Triton B at the rate of 3 fl. oz./100 gallons

of water has also been recommended by Lord et al.(l972) at the Univer­

sity of Massachusetts. The first spray is applied two weeks after

petal fall. In Washington, calcium chloride has been preferred to

calcium nitrate since the latter has impaired fruit colour of certain

cultivars such as Golden Delicious. Since Ca does not efficiently move

from the leaves to the fruits, Ca sprays must be applied directly on

the fruits (Stebbins, 1972). In cases of extreme fruit Ca deficiency, postharvest dips of 4% CaC12 may give good results in preventing breakdown (Mason, 1973; Porritt et al. 1975). For maximum protection

both sprays and dips can be used.

Lack of apple samples prevented me from doing a boron analysis and

zinc was only partially analysed for the same reason. Nonetheless B c was found very important by Lidster et al. (1975) who stated that K - 92 - . c

and B accounted for 5% of the variability associated with the incidence

of the Spartan breakdown as compared with 62% for Ca. It is possible

that application of B salts to B deficient apple trees could help

prevent the development of Spartan breakdown. Zinc, which has been

found to reduce Ca stress (Shear and Faust, 1971) should not be

overlooked especially in the orchards of the Okanagan Valley where

it is frequently deficient (Swales, 1976}.

3.l.l.C.3. Fruit firmness, colour, specific gravity and moisture

content

Nutritional and other phisiological factors:

Firmness. Flesh firmness during the first 3 weeks in storage was

a good predictor for Spartan breakdown (Fig. 10). Its correlation

with the incidence of breakdown (P = -.94) was negative and highly significant. Quebec Spartan apples were slightly firmer at harvest and

there were significant differences in firmness among the size catego­

ries (Table 10). Since the B.C. apples were in general larger, they

would be expected to be softer (Smock and Neubert, 1950).

Red Colour. Statistical analysis of the amount of surface red

colour of the Spartan apples from Quebec and B.C. indicated no signi­

ficant difference except that the smallest fruit from B.C. were

significantly greener (Table 11). The correlation matrix (Table 14)

indicated no correlation between the incidence of breakdown and the

amount of surface red colour. Similarly, a fruit internal chlorophyll - 93 - c

appraisal by Lidster et aZ. (197 5) indicated no relationship to break­

down.

Specific gravity. The principal factors which affect the specific

gravity of an apple are its water content and its gas content. Water

is the apple most abundant constituent accounting for approx 84% of

its weight (Smock and Neubert, 1950). Therefore, the weight of an

apple fruit depends largely upon its water content whereas the floating

force of an apple in water is mainly attributable to the air pockets

of its core cavity and to the volume of the gases located in its

intercellular spaces. Wilkinson and Fidler (1973) maintained that

the total air volume of the apple ranges from 20 to 25% of its total

volume.

The B.C. Spartan apples were slightly but significantly denser

than the Quebec ones (Table 12). A recent investigation by Granger

(unpublished, 1978) revealed that the core cavity of the B.C. Spartan

apples are smaller than in Quebec Spartan apples with an average

difference of 10 to 15%. This probably explains why the Quebec Spartan

apples had a greater floating force in water than the B.C. Spartan

apples. From 1.5 to 3.5% of the gases of a Spartan apple are located

in its core cavity (Granger, 1978, unpublished).

However, as pointed out earlier the difference in size between

small and large apples may be due to an increase in cell number per

fruit as well as to an increase in cell size. The fact that B.C. - 94 -

apples contained significantly more P (Table 8) than the Quebec apples

suggests that they may have contained more cells per unit of tissue

weight particularly in the peel (Meyer and Anderson, 1952). Lebedev

(1970) found that excess P increased plant weight of apple trees. If

the B.C. apples do have more cells per unit of weight or volume than

those from Quebec they would also have a larger total volume of

intracellular spaces since as the size of the cells becomes smaller

their aggregate surface area becomes greater. Furthermore, since

specific gravity declined as size increased in both B.C. and Quebec

apples, larger apples from both locations probably had more cells

surrounded by a larger total volume of intracellular 'free'. Phan

Phuc (1976) found that the larger the apple the larger the intercellular

'free' space per unit of volume. Gas circulation becomes gradually

easier as the fruit increases in volume. However, fruit respiration

rate decreases (Phan Phuc, 1976). As will be shown later, this

supports the findings shown in Table 20 that the extra large apples

respired and released ethylene significantly less than all others.

Moisture content. At first it seems illogical that the Quebec

apples which had slightly higher flesh moisture content than the B.C.

apples should be significantly less dense (Table 12). However, the

much larger core cavity of the Quebec apples (see above) probably

explains this difference. The average flesh moisture levels of the

Spartan apples from both provinces expressed in Table 12 ranged from c 83.57 to 86.05. These results agree with those of Smock and Neubert (1950) who considered 84% fruit moisture content as an acceptable - 95 -

overall average for the most important apple cultivars in North

America. In my experiment the location effect was greater than the

size effect and the peel moisture content of all apples ~~s lower

than that of the flesh. This probably reflects the richer mineral

content of the peel and cytoplasm. No relationship between either

peel or flesh moisture percentage and breakdown could be found

(Table 14) although others have shown that enhancing moisture loss

reduces breakdown incidence (Lidster and Porritt, 1978).

Cultural and environmental factors

Firmness. My findings agree with Lidster et aZ. (1975) who

found that improved firmness of Spartan apples· is associated with

small fruit diameter. It might therefore be adviseable to regulate

the crop so as to obtain smaller and firmer fruits. It should be

borne in mind that moderate thinning increases fruit dry weight and

Ca content whereas overthinning produces oversized fruit likely

to he too soft for long storage (Quinlan, 1969).

Another way of avoiding oversized fruits could be to prune Spartan

trees with moderation. Over-pruning enhances tree vigour which favours

the production of soft apples (Shear, 1975). Granger (1970) found that

hea~ily-pruned Mcintosh trees, on which the leaf N content in mid-July

exceeded 2.15%, produced soft fruit. That level of N in Mcintosh

leaves had been found by Heeney and Hill (1960) to be critical for the 0 incidence of soft Mcintosh apples. Smock (1973) also suggested that - 96 -

the soft Mcintosh problem was aggravated by heavy pruning. Similarly,

excessive N fertilization could also eventually decrease the firmness

of apples (Montgomery et al. 1962).

Orchard applications of Ca salts are known to improve the keeping

quality and firmness of Spartan apples (Looney, 1977). However, it would seem important in the dry B.C. interior area to spray the trees

repeatedly with these salts since the penetration of Ca through the

skin of the fruit is less effective when the relative humidity is low

(van Goor, 1973). TheCa salts used in a pre-storage dipping solution

have also improved the firmness of Mcintosh apples (Mason et al. 1975A).

Ca dips might also improve the firmness of Spartan apples in storage.

3.l.l.C.4. Juice acidity and soluble solids content

Nutritional and other physiological factors

Juice acidity. Lidster et al. (1975) failed to find a significant

relationship of titrateable acidity to Spartan breakdown. This agrees with the data from the present study which failed to associate titra­

teable acidity, expressed as per cent malic acid, with the incidence

of Spartan breakdown (Table 14). However 1 we did find that B.C. Spartan

apples were significantly higher in titrateable acids than the Quebec

ones. There were no significant differences due to fruit size (Table

13) although according to Martin (1954) light-crop fruit, that is fruit

which are normally quite large, have higher acidity levels. On the

other hand Eaves et al. (1964) reported that Mcintosh trees with low

leaf N levels produced fruit of higher acidity. . - 97 -

The acid content of a fruit has been found to reflect its K

content (Wilkinson, 1958; Wood and Looney, 1977). Bangerth (1974)

has also found that H+ ion in fruit acids, can antagonize the function

of Ca. From what I found, a level of .56% for titrateable acidity

may be critical since it corresponds roughly to a peel K level of

.800 (%dry wt.) and a flesh K level of .770 (%dry wt.) (Tables 6 and

13).

Therefore a quick juice acidity test may be a practical way of

finding roughly the K content of a fruit and this in turn could indicate

its susceptibility to breakdown. It must be remenbered that light

crops lead to higher acidity fruits which do not keep very well.

Soluble solids content. According to Martin (1954), the percentage

of soluble solids in apples depends on their cropping pattern. A light

crop gives low levels of soluble solids which increase as the crop

becomes heavier. A subjective assessment indicated that the Summerland

Spartan apple trees chosen for our experiment bore, at least in 1974,

larger crops than the Fresniere trees. Martin's (1954) suggestion

might therefore explain why the apples from the Quebec trees had less

soluble solids. In fact, the Quebec apples contained significantly

less soluble solids than the B.C. apples regardless of the fact that the

smallest fruits were significantly higher in soluble solids than the

biggest fruits from both provinces. While Martin (1954) found no corre­ 0 lation between soluble solid levels and breakdown, Lidster et al. (1975) did obtain a positive relationship with B.C.-grown Spartan apples. No - 98 -

relationship to breakdown was found in the present study.

Cultural and environmental factors

Soluble solids and juice acidity. The B.C. apple trees, exposed to higher solar radiation than the Quebec Spartan apples, probably had a higher photosynthetic rate and consequently were significantly higher in soluble solids and acidity (Table 13). Along with Lidster et al.

(1975) we failed to find soluble solids or acidity correlated to

Spartan apple breakdown (Table 14). Similarly Kawamata (1978) could not find total sugars correlated to pear breakdown. However, Lidster et al. (1975) stated that low levels of soluble solids and titrateable acids were associated with minimum breakdown development.

3.1.2. Comparison Between British Columbia and Quebec Spartan

Apples With Regard to Postharvest Respiration and Ethylene

Production Rates

3.1.2.A. Materials and methods

On October 16, 1974, one week after they were placed in cold storage,

15 randomly chosen Spartan apples of each size category from Quebec and

British Columbia were weighed and 5 fruits were put into each of 3 respiration jars connected to a constant air flow apparatus (Fig. 16).

The 18 jars (6 sizes x 3 replicates) were laid out in a completely · randomized block design. A flow rate of approximately 1.2 liters of air per hour was maintained. A rotameter type flow meter (Matheson FM - 99 -

1042B) was used to measure the flow rate 3 times daily. For co2 measurement, the output from each jar was connected to an infrared co2 analyser (Beckman 15A) giving a millivolt readout which was then converted to percent from a standard curve. Here is a sample co 2 of the respiration rate calculation for replicate I of the small apples from Quebec on October 17» 1974: a) Formula: F = L/hr X 10 kg

F = Fruit wt.: flow rate integrating factor L/hr = Liters of gas per hour flow rate

kg = Fruit wt~ in kg b) Calculations: F = 1.414 X 10 = 34.85 .420 c) Formula: F x % = ml /kg of fruit per hour co2 co2 % = Value from the infrared analyzer compared to a standard co2 co2 curve. d) Calculations: 34.85 x .465 % C02 = 16.21 ml C02/kg.hr

For ethylene analysis a 2 ml gas sample was taken from each respi- ration jar with an hypodermic syringe by directly puncturing the rubber outlet tube from each jar. This sample was injected into a

Rewlett Packard Model 5711A gas chromatograph (Fig. 17). This instrument was equiped with a 6 ft x 1/8 inch glass column filled with

80-100 mesh activated alumina. The instrument was operated isothermally at 125 0 C. The carrier gas was nitrogen at 30 ml/minute. Hydrogen at

30 ml/minute and air at 250 ml/minute were the combustion gases for - 100 -

the flame ionization detector. Retention time was about 2 minutes. The limit of sensitivity was about .OS ppm ethylene in a 2 ml sample. Two ml of standard gas (100 ppm ethylene) was injected for comparison purposes. A Sargent Model SR 1 millivolt strip chart recorder completed the apparatus.

For ethylene production of the sample just mentioned the calculation was as follows:

From the formula: (pk height of sample) (attenuation (cone of u c H /k h of sample) . . . std in ppm) L/hr ... 2 4 g. r = 1------~ (pk height of std) (attenuation of std) kg where 1-11 = microliter pk weight = recorder response as % of 100 attenuation = sensitivity of recorder cone = concentration std • standard L/hr = !iter per hour kg.hr = kilogramme of fruit per hour

Sample A for 18/10/74 • 30 x 32 x 100 1 1.392 ) = 29.26 vl/kg.hr [ 42.5 X 256 .420

Sample A for 17/10/74 • 30 x 32 x 100 1 1.464 = 30.78 vl/kg.hr 42.5 X 256 .420 - 101 -

Ethylene and determinations were made daily for 12 days co2 after which the fruit were tested for firmness, juice acidity and

soluble solids.

3.1.2.B. Results

3.1.2.B.l. Respiration at 20 0 C of B.C. and Quebec Spartan apples

removed from 10 C storage shortly after harvest

The means of production rates measured daily between October co2 17 and October ·27, 1974 indicated that smaller fruits from both

locations tended to respire at a higher rate per unit weight than

the larger fruits (Table 20). In general the Quebec fruits respired

at a slightly higher rate than those from B.C. The respiration rate

declined steadily between October 17 and October 27 indicating that

these fruits were post-climacteric with regard to co2 production (Table 20). On a weight basis there was no significant correlation·

between the respiration rate and breakdown or any of the other factors studied except for fruit firmness at harvest. In this latter

case the correlation was positive (Table 14).

Conversely, when the respiration rate was expressed on a per

fruit basis the smallest fruits respired more slowly than the largest

ones and the Quebec apples had lower respiration rates than the B.C.

ones (Table 21). On the same basis, respiration rate was correlated .0 positively with the percentage of rots, the content of peel Mg, flesh Mg, flesh K, flesh P, with the release rate both on a per weight c2n4 - 102 - I

5 apples each for every size Figure 16 - Respiration jars containing • category from Quebec and B.C . - 103 - I

Figure 17 - The Hewlett Packard gas chromatograph used for determining • ethylene in the apple samples shown in Figure 16. - 104- c

and per fruit basis and finallyt with breakdown. It was correlated

negatively with fruit firmness at harvest (Table 14).

3.1.2.B.2. Ethylene production at 20°C

On a fresh w~ight basis the Quebec fruits tended to produce more

· ethylene than fruits from B.C. (Table 20). In general as the apple

size increased the H production decreased. The pattern of ethylene c2 4 production by all lots indicated that they were clearly into their

climacteric phase. On a fruit weight basis H production was c2 4 correlated negatively with breakdown incidence and rot development

in storage, peel Mg, peel P, flesh P, flesh firmness at harvest

and with co2 production on a per fruit basis (Table 14).

The ethylene release rate per apple gave quite a different

picture. In general the bigger the fruit the higher was its H c2 4 release rate but there was no clear difference attributable to location.

The tendancy to produce more c2H4 with aging was maintained except for the last sampling date when the c H release rate decreased 2 4 . (Table 21). On a per fruit basis H production was correlated c2 4 'negatively with peel Ca, flesh Ca, flesh firmness at harvest and with

c2H4 production on a per weight basis. It was correlated positively with fruit rotting in storage, peel Mg, flesh Mg, peel K, flesh P

and with co2 production on a per fruit basis (Table 14). - 105 - c

3.1.2.B.3. Some qualitative changes of Spartan apples held for

12 days at 20°C

Fruits held at 20 0 C undergo a number of physiological changes which

can be used as evidence of ripening or lack of ripening. In the present

study fruit firmness, juice soluble solids and juice acidity measure-

ments were used to assess ripening activity during the 12-day holding

period at 200 C.

Fruits from B.C. softened substantially more than those from ~ Quebec and larger fruits softened more than smaller fruits from both

locations (Table 22). The location effect was much greater than the

effect of fruit size. The decrease in firmness from harvest to that

after 12 days at 20 0 C was more than twice as high in the B.C. fruit.

Fruit firmness after 12 days at 20°C correlated negatively with rot

and breakdown development in storage and with peel Mg, flesh K,

flesh P, production on a per fruit basis, and H production on a co2 c2 4 per fruit basis. It correlated positively with peel Ca, flesh Ca,

and co2 and c2H4 production on a weight basis (Table 14).

Juice soluble solids did not change in any consistent pattern

during the 12-day holding period (Table 23). B.C. apples maintained

their small but significant advantage in soluble solids level. The

percentage of fruit flesh soluble solids" was not correlated with

any other factor (Table 14).

Juice acidity decreased in all lots during the holding period - 106 -

(Table 24). The percentage drop was slightly higher in the B.C. fruit

(20.3 vs 14.9%) but B.C. fruits were still higher in acidity than

Quebec fruits. Larger fruits from both locations lost less acidity

than the smaller fruits. Acid content as malic acid correlated posi­

tively with peel K, flesh K, pell P and flesh P. It correlated nega­

tively with peel and flesh moisture content (Table 14).

3.1.2.C. Discussion

Preamble

The customary way of expressing and H release rates from co2 c2 4 apples is on a fruit fresh weight basis. However, to help explain

some correlations relating other factors studied to fruit and co2 R production, both were expressed on a per fruit basis as well c2 4 as on a per weight basis (Tables 14, 20 and 21).

The respiration rate per kg of fruit per hour proved to be lower

for large apples than for the small fruits (Table 20). This may relate

to the changing fruit surface/volume ratio. On the other hand a direct

relationship is exhibited when the respiration rate is expressed on a

per fruit basis (Table 21). This explains why inverse correlations are

found depending on whether the ~espiration or ethylene production rates

are expressed on a per unit weight or on a per fruit basis (Table 14).

According to Hulme (1971), expressing the biochemical composition of

fruits on a unit weight basis is not always applicable and he wrote: 0 - 107 -

Table 20. Average carbon dioxide and ethylene production rate per unit weight of fruits of varying sizes from Quebec and B.C. held for 12 days at 20°C after 10 days in cold storage

1 Location Size category n

2 2 Quebec Small 3 11.34 a 31.62 a Quebec Medium 3 ·9.93 be 28.37 a Quebec Large 3 9.29 cd 32.11 a B.C. · Medium 3 10.07 b 27.28 a B.c. Large 3 8.15 e 20.03 b B.C. Extra Large 3 8.82 de 18.30 b

Quebec Medium & Large 6 9.64 a 30.25 a B.C. Medium & Large 6 9.11 b 23.70 b

Quebec Small 3 11.34 a 31.62 a Quebec & B.C. Medium 6 10.03 b 27.78 b Quebec & B.C. Large 6 8.72 c 26.07 b B.C. Extra Large 3 8.82 c 18.30 c

1974 sampling dates

17 Oct. 11.30 a 15.32 a 19 Oct. 10.72 a 20.02 ab 21 Oct. . 9.84 b 22.52 be 23 Oct. 9.77 b 33.81 de 25 Oct. 8.17 c 36.91 de 27 Oct. 7.84 c 29.12 de 1 . Number of replicates of 5 apples each. 2 Mean separation within each analysis by Scheffe's (1950) test performed c at the 5% probability level. - 108 -

Table 21. Carbon dioxide and ethylene production by apples of varying sizes from Quebec and B.C. held for 12 days at 20°C after 10 days in cold storage

1 Location Size ea tegory ml co /apple~hr_~l c H /apple.hr. n 2 2 4 2 2 Quebec Small 3 0.94 a 2.64 a Quebec Medium 3 0.93 a 2.67 a Quebec Large 3 1.07 a 4.04 be B.C. Medium 3 1.12 a 3.06 ab B.C. Large 3 1.46 b 3.62 abc B.C. Extra Large 3 2.07 c 4.30 c

Quebec Medium & Large 6 1.00 a 3.35 a B.C. Medium & Large 6 1.29 b 3.34 a

Quebec Small 3 0.94 a 2.64 a Quebec & B.C. Medium 6 1.02 a 2.86 a Quebec & B.C. Large 6 1.26 b 3.83 b B.C. Extra Large 3 2.07 c 4.30 b

. 1974 sampling ml co2/apple.hr. ~1 c2H/apple.hr dates

17 Oct. 1.46 a 1.84 a - 19 Oct~ 1.42 a 2.43 b . 21 Oct. 1.07 b 2.82 b 23 Oct. 1.28 c 4.30 c 25 Oct. 1.32 c 5.09 d 27 Oct. 1.05 b 3.87 c

l Number of replicates of 5 apples each. 2 Mean separation within each analysis by Scheffe's (1950) test performed at the 5% probability level. - 109 -

Table 22. Firmness of fruits used for co and c H production 2 2 4 studies and following a holding period at 20 0 C from

17/10/74 to 27/10/74.

1 Location Size category n Original Firmness b firmness after 12 days (kg) (kg) at 20 0 C (kg) ...... 2 2 Quebec Small 3 8.20 a 7.59 a 0.68 Quebec Medium 3 7.60 b 6.99 b 0.61 Quebec Large 3 7.29 c 6.01 c 1.29 :s.c. Medium 3 7.64 b 5.80 cd 1.85 B.C. Large 3 6.91 d 5.43 d 1.49 B.C. Extra Large 3 6.35 e 4.18 e 2.17

Quebec Medium & Large 6 7.45 a 6.50 a 0.86 B.C. Medium & Large 6 7.28 b 5.62 b 1.84

Quebec Small 3 8.20 a 7.59 a 0.68 Quebec & B.C. Medium 6 7.62 b 6.39 b 1.23 Quebec & B.C. Large 6 7.10 c 5.72 c 1.39 B.C. Extra Large 3 6.35 d 3.18 d 2.17

1 Number of replicates of 5 apples each. 2 Mean separation within each analysis by Scheffe's (1950) test performed at the 5% probability level. - 110 - c Table 23. Soluble solids content of fruits used for co2 and c2H4 production studies and following a holding period at

20°C from 17/10/74 to 27/10/74 1 Location · Size category n At harvest After 12 (%) days at 20 0 C D (%) .. '' . . ' ' ...... - ... - 2 2 Quebec Small 3 13.27 ab 12.33 b -0.94 Quebec Medium 3 11.98 d 12.50 b +0.52 Quebec Large 3 12.65 c 12.13 b -o.52 B.C. Medium 3 13.54 a 13.53 a -o.Ol B.C. Large 3 13.33 ab 12.53 b -o.77 B.C. Extra Large 3 12.94 be 13.53 a +0.59

Quebec Medium & Large 6 12.32 b 12.32 b o.oo

B.C. Medium & Large 6 13~44 a 13.03 a 0.41

Quebec Small 3 13.27 a 12.33 c -o.94 Quebec & B.C. Medium 6 12.76 b 13.01 b +0.25 Quebec & B.C. Large 6 12.98 a 12.33 c -o.29 B.C. Extra Large 3 12.94 ab 13.53 a +0.59

1 Number of replicates of 5 apples each. 2 Mean separation within each mean by Scheffe's (1950) test performed at the 5% probability level.

c - 111 -

0 Table 24. Titrateable acidity (as percent malic) in the juice

of fruits used for and H production studies co2 c2 4 and following a holding period at 20°C from 17/10/74

to 27/10/74

1 Location Size category Original n Acidity A acidity after 12 days ~ (%) at 20°C (%)

2 2 Quebec Small .455 b 3 .352 e -.102 Quebec Medium .443 b 3 .401 cd -.042 Quebec Large .438 b 3 .383 de -.055 B.C. Medium .564 a 3 .424 be -.140 B.C. Large .552 a 3 .439 b -.113 B.C. Extra Large .558 a 3 .470 a -.088

Quebec Medium & Large 6 .392 b+ -.049 B.C. Medium & Large 6 .432 a -.126

Quebec Small .455 c+ 3 .352 d+· -.102 Quebec & B.C. Medium .503 b 6 .393 c -.090 Quebec & B.c. Large .495 b 6 .431 b -.084 B.C. Extra Large .558 a 3 .470 a -.088

1 Number of replicates of 5 apples each. 2 Mean separation within each analysis by Scheffe's (1950) test performed at the 5% probability level.

0 - 112'- c "The expression in tenns of fresh weight has little meaning when the whole organ is in a state of rapid expansion. Change in anthocyanin illustrates well this point; although the concentra­ tion of the fraction is falling throughout most of the growth period, its synthesis (in terms of amount per fruit) continues 11 until maturity is reached •

3.1.2.C.l. Respiration

Nutritional and'other physiological factors

Probably due to the surface/volume ratio, respiration per fruit

was significantly and positively correlated to breakdown (Table 14).

Smock and Neubert (1950) have mentioned that apple respiration is

primarily a surface phenomenon. Therefore it may be more appropriate

to express respiration on a per fruit basis. On a fruit weight basis,

Kawamata (1978) found no correlation between the incidence of the

Yuzuhada physiological disorder of pear and respiration rate.

Even more to the point, Looney (1977) concluded that Spartan breakdown

susceptibility does not relate to fruit respiration rate calculated

on a unit weight basis. Likewise I show no clear relationship between

the incidence of Spartan breakdown and the respiration rate when

respiration was expressed on a fruit weight basis (Table 14). Other

factors which correlated with respiration per fruit will be discussed

hereafter.

The percentage of rots which developed in storage was not

significantly correlated with evolution per unit weight of apples. co2 0 - 113 -

On a per fruit basis, however, a significant correlation 'rlth respira-

tion rate was seen (Table 14).. The apples which rotted the most were

the ones which respired the most (Tables 3 and 20). Hulme and Edney

(1960) suggested that one of the factors rendering the apples more

susceptible to fungal attack during senescence could be a fall in the

concentration of chlorogenic acid which they suggest inhibits the

germination of spores of the fungus Gt.oeosporoiun pe:rennans. The

senile apples which have a high respiration rate are likely to contain

a weaker concentration of chlorogenic acid and are therefore more

vulnerable to this fungus.

On a unit weight basis, peel and flesh Mg content related

directly to fruit size (Table 14) and therefore the strong correlation

between peel and flesh Mg and respiration rate per fruit could be

merely explained by the mutual relationship to fruit size.

These high correlations may be partly explained by the observation

by Meyer and Anderson (1952} that

"Magnesium plays a role in phosphate metabolism of plants and indirectly therefore in the respiration mechanism".

In fact, significant correlations were found between flesh P and

peel Mg or flesh P and flesh Mg (Table 14). Interestingly, only

flesh P strongly related to Spartan breakdown.

Contrary to what Bangerth (1974) and Faust and Shear (1972) have

found, I have shown that, on a unit weight basis, the apples which c respire the least {Table 20), have the lowest Ca content (Table 7). However, the correlation coefficient relating these two factors was - 114 -

not significant. It must be noted that I examined different apple

cultivars than the above-mentioned researchers and used post-climacteric

apples while they used pre-climacteric ones. On the other hand, Snay

and Bramlage (1973) found that Ca can either reduce or stimulate the

respiration of isolated mitochondria.

The amount of K in these apples did not correlate with respiration

calculated on a unit weight basis. However on a per fruit basis res-

piration rate was positively correlated with flesh K (Tables 6, 14 and

20). It should be noted that the differences inK were due to

location and not to size within location. Thus, the high correlation

with respiration per fruit is probably due to more than a simple

mutual relationship to fruit size. High acidity is often associated

with high K levels (Wood and Looney, 1977). Perhaps the high K and

acidity of the Summerland app1es explains part of this fruit respira-

tion: fruit K relationship.

Fruit respiration per fruit was negatively, and per unit weight

positively correlated with fruit firmness. Protopectin, as explained by

Hulme (1971), is largely responsible for binding the apple cells together

and thus giving the flesh its rigidity and firmness. Quoting Neukom's

work Hulme (1971) wrote that protopectin consists of chains of polygalac-

turonic acid eross-linked in various ways with. metals {Ca++ , Mg++ and +f+ possibly Fe ) and hydrogen bonding between hydroxyl groups and, possibly.

by methylene bridges. Since it has been suggested by Wiley and Stembridge c (1961) that starch and starch-like substances would be intimately associated with protopectin it seems reasonable to believe

that the degradation of starch as substrate for respiration should

cause fruit softening.

Cultural and environmental factors

In the light of these results, respiration studies conducted early

in the storage season might help predict-potential Spartan breakdown

problems in cold storage. However, one would have to express respi­

ration rate on a per fruit basis. Cold storage operators might also

note that respiration per fruit was negatively correlated with fruit

firmness and firmness in turn was negatively correlated with Spartan

breakdown (Table 14).

3.1.2.C.2. Ethylene production

Nutritional and other physiological factors

Like respiration, production rates were negatively correlated c2n4 with breakdown on a unit weight basis and positively correlated on a

per fruit basis (Table 14). The positive correlation was the highest.

It has been recognized that the climacteric respiration peak usually

precedes that of (Smock and Neubert, 1950). My post-climacteric c2n4 apples reached a peak for H production on October 25 while there c2 4 was a more or less steady decrease in respiration (Tables 20 and 21). c -116- c

On a unit weight basis, c a production was negatively correlated 2 4 with the percentage of rots which developed in storage (Table 14). When

calculated on a per fruit basis, this relationship was positive but not

clearly identified. The larger apples which produced the least c2n4 per unit of fruit weight were also softer and were apparently more

susceptible to rotting.

On a unit weight basis production rate was negatively corre­ c2n4 lated with peel Mg (Table 14). This relationship is difficult to

interpret. However, since Mg plays a very important role in the

chlorophyll molecule it is interesting to find it antagonistic to ' .which is known to hasten de-greening (Meigh et aZ. 1967, Bain c2n4 and Mercer 1964; Rhodes and Wooltorton 1967).

No correlation was found between the amounts of Ca present in

the experimental apples and their release rate (per unit weight) •. c2n4 ~ As indicated earlier, Faust (1974) found an inverse relationship

between Ca content and respiration of apple. This suggests that a

similar relationship may exist between Ca content and release rate c2n4 _and indeed, Poovaiah and Leopold (1973) report that Ca can inhibit

abscission and therefore relates strongly to c n action~ if not to 2 4

c2n4 evolution. On a per fruit basis, an inverse relationship to Ca, similar to that discovered by Faust (1974) was observed. However,

the complexity of this Ca: production relationship seems a long c2n4 c way from being resolved. For example, a synergistic effect of Ca and kinetin on production by the mungbean hypocotyl has .been reported c2n4 - 117 - c (Lau and Yang, 1974).

The levels of Pin the experimental apples seemed to be consis-

tently related to their ability to release c2R4 (Table 14). Both

peel and flesh P were negatively correlated to c2H4 production per kg of fruit per.hour. Only flesh. P was positively correlated to the

H release rate per apple. Suwwan and Poovaiah (1978) found that c2 4 up to 60 days after anthesis, that is during the period when the H c2 4 release rate increases in tomato fruits, neither bound nor soluble

flesh P increased. It will be recalled that large differences

existed in peel P between Quebec and B.C. apples but that fruit size

effects within location were small (Table 8). Furthermore, since the

larger B.C. apples released less H on a unit weight basis these c2 4 significant correlation values may or may not be indicative of a

physiological relationship. With c H production being related to the 2 4 metabolism of Krebs cycle acids {Burg and Thimann, 1960), one might

expect that P is involved more or less directly since, as proposed

by Thompson and Spencer (1966) P plays a catalytic role in pyridoxal

phosphate Fe+f- and TPP Mg* •

Finally other metals or substances not dealt with previously

have been found to inhibit the production of H • Co and Ag are c2 4 particularly potent inhibitors. tau and Yang (1976) found that Co

largely inhibited the conversion of methionine to H in apple c2 4 tissue. That finding confirmed the belief that methionine is a pre-

0 cursor of c2H4 {Abeles, 1973; Baur et al. 1970; Burg and Thimann, - 118 - c

1960). Working with tomato plants Beyer (1976) found that Ag applied

foliarly as AgN0 is a potent inhibitor of action. Milder 3 c2n4 inhibitors such as Pd, Hg and even were reported in the lite­ c2n4 co2 rature {Lau and Yang, 1976; Beyer, 1976).

Thus it may have been unfortunate that the Quebec and B.C. apples

were not compared for contents of some of these elements. For example,

high Ag or Co in B.C. apples may explain some of the lower production c2n4 rate observed in those fruits.

Cultural and environmental factors

It is unlikely that production rates will be used for predic­ c2n4 ting or diagnosing Spartan breakdown. The required instrumentation is

expensive and the technique are relatively difficult. The amount of

ethylene produced depends not only on the stage of the climacteric

but also on fruit size and perhaps on the nutritional content. The

fact that softer fruits at harvest produced less c2n4 seems to be contrary to previous reports. Further experimentation is needed to

confirm or refute a relationship between ethylene production rate and susceptibility to storage breakdown.

3.1.2.C.3. Some qualitative changes of Spartan apples held for

12 days at 20 0 C

Nutritional and other physiological factors

Firmness. Softening is recognized as a good indicator of fruit - 119 -

ripening and thus related to changes in the co and c n release rates 2 2 4 (Tables 20 and 21). There was a strong positive correlation between

firmness at harvest and production on a unit weight basis. It c2n4 was negative on a fruit basis (Table 14). These findings differ

from those of Smock and Neubert (1950) who wrote that in general,

apples which are firmer and keep longer produce less c2H4 on a unit weight basis. However, they did not class their fruits in different

size categories as was done here. My results suggest that for C02 and H production fruit size may be more important than fruit firmness c2 4 since gas exchange is primarily a surface phenomenon and is associated

with the fruit volume-to-surface ratio (Burg and Burg, 1965; Phan Phuc,

1976). Furthermore as stated by Burg and Burg (1965), only the peel

creates a barrier of major importance to gas diffusion. It is sugges-

ted here that the peel of large fruits. especially when rich in Mg

such as that of B.C. apples, would be a stronger barrier to gases than

the low Mg peel of the smaller Quebec apples.

The loss of apple firmness between harvest time and after 12 days

at 20 0 C was more than twice as great in the B.C. fruit compared to

the Quebec fruit (Table 22). When both groups of apples were removed

from. their respiration chambers they were almost as soft as comparable

apples which were stored for 8 1/2 months at 1°C (Tables 10 and 22).

·soluble·solids. The soluble solids content of the Quebec apples

did not change during the 12 day holding period in the respiration 0 chambers while that of the B.C. apples decreased slightly (Table 23). - 120 -

It would appear that the utilization of sugars for respiration does

not directly deplete the soluble solids pool. This energy probably

comes from the pool of organic acids (see below). Kawamata (1978)

reports that acid loss can be accompanied by accelerated sugar meta­

bolism.

Malic acid. Like soluble solids, fruit acidity at harvest failed

to show a strong correlation with the respiration and H release rate c2 4 of apples (Table 14). However, acids with malic acid as the main

constituent (Smock and Neubert, 1950) do act as substrate for respira­

tion along with sugars. The acidity decreased in fruits from both

locations with aging (Table 24). It seems odd that the Quebec apples,

which respired at a faster rate, had a smaller decrease in acidity

(about a 11% decline) than the B.C. fruit (about a 23% decline).

Admittedly only the medium and large apples were compared in this case.

A more normal pattern is shown for the size categories when all groups

of apples are taken into account. For example, the small Quebec apples

lost 23% of their original acidity whereas the extra large B.C. apples

lost only 16% during the 12-day holding period.

Cultural and environmental factors

Firmness. The use of a portable fruit pressure tester is essential

for determining whether a particular field lot will be acceptable to

consumers shortly after harvest or after long storage. However, fruits c from different locations may soften at different rates in storage or - 121 - c

at higher temperatures in the market place. This study was an attempt

to assess the latter situation. It would appear that the Quebec fruit

soften less rapidly.at 20°C which should be an advantage. However,

the differences were not large and are indicative only.

Soluble solids and acidity. Fieldmen can measure soluble solids

easily with a hand refractometer, but acidity determinations are more

difficult. The loss of organic acids during the holding period at 20 0 C

is reflected in a decline in flavour which will be recognized by the

consumer. Again, the B.C. apples lost more acidity than those from

Quebec but the fact that they were considerably higher in acidity

initially is to their advantage. - 122 -

3.2. Absorption of \ 5Calcium by Apple Rootstocks and Scion Cultivars 0

3.2.1. Absorption of ~ 5 Ca by two cultivars on four rootstocks

3.2.l.A Materials and methods

Preparation of the plant material

Fall-dug virus-indexed rootstock trees of H 26, M 7, MM 106 and MM 111 clones were shipped to the Summerland Research Station in early

December 1974. They were then kept in a nursery storage at 2.8°C in moist peat moss for one month. On January 6 and 7, 25 trees of each clone were bench-grafted to Spartan and 25 trees to a non-spur strain of Delicious (Harrold Red) and returned immediately to another nur- sery storage room where the temperature was maintained at 12.8 0 c.

On February 5, 1975, 192 of the most uniform trees were planted in 3-liter plastic pots filled with coarse (no. 14) silica sand (Fig. 18A). The trees were randomly placed on the greenhouse benches. To increase exposure to light each tree was equipped with an aluminium foil reflector through which a few holes were poked for feeding with a nutrient solution and for watering (Fig. 18B). The trees were fed 5 days a week with a full nutrient Long Ashton solution as described by Hewitt (1966). Since the pH of the nutrient solution was at 4.3 it was raised to 6.8 by adding 12.5 ml of lN NaOH per 20-liter carboy. This was intended to facilitate the uptake of all elements in the solution by the plant. - 123 -

0

All grafts were successful and produced very lush growth (Fig. 18C).

Supplementary light was provided between 0600 to 2000 hrs. These lights

produced between 800 and 1000 foot candles at plant level. Insect and

disease control was achieved by spraying weekly with appropriate insecti-:

cides and fungicides.

Treatments with ~ 5Calcium

On March 30, 1975 10 m Ci of ~ 5cac1 2 (specific activity of 13.2 Ci/g Ca) arrived at the Summerland Research Station from Montreal* in

0.5 N HCl. All preparative work was done in the radioisotope laboratory

of the Agriculture Canada Research Station, Summerland, B.C. Liquid

scintillation analyses were completed in the Plant Pathology section

of this research center.

A series of preliminary trials were conducted with a few trees

decapitated to 3 leaves (Fig. 18D) on April 16 and 18, 1975. Concen­

trations of 10, 20, 40 and 80 p Ci were tested in 2.5 l milk

cartons of full nutrient Long Ashton solution in which apple trees

had been growing for one week. These preliminary trials indicated

that a concentration of 80 p Ci was too high and 10 p Ci was too low

for good detection of the ~ 5 Ca in plants analysed one week after

application.

Sixty-two days after the trees were put in the greenhouse the

plants of the first block (32 trees) were removed from the pots by

* ICN Research Products, 675, Montee de Liesse, Montreal 377, P.Q. - 124 -

0

injecting water in each pot and immersing it in a large pail of water

in order to prevent root breakage (Figs. 19A and B). It was important

to avoid root breakage since according to Faust (1974) 45Ca tends to

accumulate at the lesions. The trees were then transferred to 2.5-liter

polyethelene bags and placed into milk cartons. Polystyrene tree

holders were placed on top of each container (Fig. 18D).

Adequate aeration of the nutrient solution was provided by an air

pump which fed a main 25 mm ID (internal diameter) plastic pipe to

which were connected a number of .089 cm ID trickle irrigation micro­

tubes (Figs. 18D and 19C). Immediately after they were transferred

to the carton containers each tree was headed back to the 3 oldest

leaves and the weight of plant tissue removed was carefully recorded

{Fig. 19D). The total length of the shoots removed was also recorded

(Fig. 21A) and the total area of all the leaves.from each tree was

found by matching each leaf with a correspondant model of which the

area had been previously measured (Fig. 20).

On April 15, 1975 immediately after the first group of trees

were headed back to 3 basal leaves (Fig. 21B) one pair of trees

of each combination was treated with 23 or 46 ~ Ci of isotopic CaC1 2 in 2500 ml of nutrient solution as shown in the flow chart for block

I (Table 25). - 125 -

Table 25. Flow Chart for Block I.

Tree IJ

8 ~29 M26~ 30 ~D<31 32 ~17 M7< 18 »<::::::21 22 .16 trees at 23 ll C

MM 106<.<:::::~: ~24 - ----.._28

~ ----25 MM 111 26 without BA+ GA treatment M26<.~ .· n-<:::~~ M7~ 5~~ . ~ D~34 16 trees at 46 p Cf .. ~

s~9 MM 106~ ---_10

Legend: S = Spartan D~ D • Harrold Red Delicious s -c:::::::::;2 MM 111~ 12 ~D~l3 ----16 - 126 -

Table 26. Number of days during which 45Ca was absorbed by apple

trees in each block in 1975

Block Treatment Starting date Completion date Time in days with 1 BA and GA 3 I No April 26 May 16 20

II Yes May 3 May 24 21

III No May 12 June 2 21

IV Yes May 15 June 5 21

V No May 21 June 11 20

VI Yes May 23 June 13 20

It took approximately 12 days to obtain young shoots averaging

6 cm in length but each tree was allowed to absorb 45Ca during at

least 20 days (Table 26). By that time the average length of the

new shoots was around 12 cm. In the greenhouse compartment where

the trees were held after treatment with isotopic Ca the light

banks were lowered to approximately 50 cm above the plants. The light

intensity at plant level ranged between 900 and 1400 foot candles on

dull days and the lights were turned on at 0500 and off at 2100 hrs

daily. On bright sunny days the light intensity at the plant level

reached 7000 foot candles. Aluminium foil reflectors were also put on

top of each milk carton to.improve the radiation under each leaf. An

air conditioning system maintained compartment air temperature at

about 21°C.

1 c will be described in 3.2.2. Fig. 18.

A Spartan/MM 111 apple tree one month after grafting. Tree is shown in 3 l plastic pot filled with No. 14 coarse silica sand.

B General tree development one month after the trees were placed in the greenhouse.

C One representative tree immediately before it was headed back to 3 large basal leaves.

D Preliminary trial with apple trees in 2.5 l milk cartons. Display of the aerating system including the pump, the main duct and the micro-tubing.

0 - 127 - I

• • - 128 - I

• - 129 -

2

40.58 cm 2

3

2 1 34.13 cm

54.52 cm 2

4

25.81 cm 2

6 19.03 cm 2

14.19 cm 2 0

Fig.20 Leaf area char~. 0

Fig. 21

A Measurement of total length of the shoots removed from every tree and collection of their leaves of which the area was measured from the chart of Fig. 20.

B Display of two blocks of trees headed back to 3 large basal leaves and treated with 23 and 46 p ei of ~ 5ea. One block was treated once with BA at 2000 ppm and with GA3 at 500 ppm one day after the trees were decapitated. GA3 at 500 ppm was also applied on these trees two days later.

C Removal of one experimental tree from its container in which it had been grown for 21 days in a full nutrient solution containing ~ 5 ea.

0 - 130 - •

• - 131 -

Preparation of the samples to be analysed for 45Ca

After a period of 20 or 21 days each tree was removed from its

container {Fig. 21C) and samples of 5 representative sections of each

tree were taken as illustrated in Figs. 23 and 26. The samples were

labelled as young shoots, old leaves, high bark, low bark and root

bark according to the location from which they were removed (Fig. 23).

The young shoots and old leaves were finely chopped with scissors in

separate 50-ml beakers (Fig. 22B). The bark samples were approximately

3 cm long cylinders as shown in Figs. 22C and D. The area of each

bark sample was obtained by tracing its contour with a pencil on a

sheet of paper and measuring the area within each contour (Fig. 22D).

The 3 locations for the bark samples were 5 cm above the graft union

11 ("high bark ), 5 cm below the graft union ("low bark") and from the

main root axis between 10 and 15 cm below the crown level ("root bark").

A diagram of a typical experimental tree is shown. in Fig. 23. The bark

samples were also finely chopped with scissors into separate 50-ml beakers.

Immediately after the samples were harvested they were weighed to

obtain their fresh weight and dried in an oven at 80°C for 12 hours.

Their weight was again recorded. They were then transferred into 0 . a muffle furnace held at 400 C during the first hour and raised

to 650°C during 5 additional hours. This program gave optimum ashing.

A too rapid temperature rise oxidizes the exterior of the tissue

samples and forms a barrier to air penetration which causes the for- mation of an inner core of carbon which does not ash properly. Fig. 22

A Harvest of young shoots.

B Chopping of old leaves with scissors before drying and ashing.

C Taking a "high bark" sample ..

D Tracing the contour of a bark sample on paper to determine its area.

0 - 132 - •

• - 133 -

Liquid scintillation procedure

Radioactivity of the samples was measured with a Beckman LS-lOOC liquid scintillation soft-beta spectrophotometer equiped with a variable window width module. The energy spectrum of ~ 5 Ca had been previously mapped on this instrument by Lidster (1975) (Fig. 24). 14 Since one variable discriminator module and one programmed C module 14 covering the entire c spectrum (0-600 window width) were available, the programmed module was adjusted to.. measure the initial one-third of the ~ 5 Ca spectrum (window width 0-360) for quench c?rrection deter-

~nations. In other words, the lower knob of the "variable discri- minator module assembly" was adjusted at 0 (outer scale) and 0 (inner scale) and the upper knob was set at 3 (outer scale) and 6 (inner scale).

The quench correction curve was determined by using the channel

3/channel 2 ratio. Chloroform (CHC1 ) was the quenching agent. 3 Increasing the volume of PCS* solubilizer from 10 to 11 ml had no effect on the channel ratios.

Each of 10 separate glass scintillation vials received 1 ml of the 46 p Ci/2500 (2.5 Z per tree container) 45Ca solution to give approximately 30,000 CPM. The same procedure was repeated with the weaker 45Ca solution to give roughly 16,500 CPM. To the initial volume a series of 10.0 ml to 10.9 ml of PCS cocktail mix was added

* PCS Solubilizer: Amersham Searle Corp. 400 Iroquois Shore Rd.,

Oakville, Ontario. - 134 -

() ~ 0 "'... 0 NUTRIENT SOLUTION+ 0 AIR BUBBLER:----F-l~\ 0 () 4 L -1,-----_:_. 5cacl 2 o_o o «~· "'

Fig. 23 Diagram of an experimental tree put in a Long Ashton full

nutrient solution to which ~~Ca was added. - 135 -

1650~,- r-- r-1-" 1- lsooo r- r- i 5500 - r- I

:... r-- 15000 !- ,-- I .,... ~45ca 14500 \CPM ...... ,t I r- I MODULE ' I 14000- I SETTING ,...... ,

r- 13500·- 1-" \:E r-- r-1-- la.. r-- ICJI ~ooo - CHANNEL3 GAIN== 2.68 1- 45 1- Ca level = 0.05 Ci t-- I 25oo -·~ ' ··--·~ ·-~- ' Cocktail = 0.5 mf H2 0 1-" 14.5 ml of ,_ t-- !2000 PCS solubilizer t-- \14c 1500,_ t-- r-f-- r- I r--_r-- !- !1000 ,--- - ....._ ...-- \ 500!- t--- - - '-- ....._ f-- ~

1100 1 1 i ! 2oo ~oo 4oo lsoo 1 soo !MODULE SETTING 1 (window width)

Fig. 24 Energy spectra of radiocalcium and radiocarbon. - 136 - c

Table 27 •. Determination of quenching by CHC1 (counts per minute) 3 Not Channel Sample CHC1 quenched quenched ratio 3/2 3 No. Ch.2 Ch.2 Ch .• 3 quenched % efficiency added.

Ave.* Ave.* 1 nil 32,197.60 31,679.52 13,007.14 .4105 .401 98.39 98.39

2 lOO ~1 32,054.65 30,500.00 18,330.5 .600 .601 95.11 95.15

3 200 tt 31,407.03 29,010.14 20,017.50 .690 .703 92.36 93.11 .... 4 300 " 30,674.80 27,993.70 21,850.00 .780 .800 91.25 91.32 0 5 400 tf 31,772.22 28,598.57 25,664.10 .897 .890 90.01 90.70 ;:1 \0 6 500 n 30,915.38 27,245.57 .932 .937 88.12 87.96 ..;t 25,393.03 7 600 " 31,087.59 26,381.57 25,618.47 .971 .968 84.86 84.39 8 700 ': 30,712.97 25,519.74 25,159.74 .985 .991 83.09 82.49 9 800 " 30,419.69 25,113.12 24,641.10 .981 .989 32.55 80.77 10 1000 " 31,202.32 23,182.65 23,301.74 1.005 .993 74.30 75.29

1 ' nil 16,892.40 16,650.20 6,538.07 .392 98.39 2 100 111 17,112.82 16,283.33 9,798.04 .601 95.15 3 200 " 16,775.73 15,743.92 11,296.90 .717 93.84 4 300 n 16,757.74 15,317.55 12,590.88 .821 91.40 .... 5 . 400 0 " 16,402.86 14,714.70 13,014.65 .884 89.70 ;:1 6 500 " 16,693.33 14,657.66 13,823.79 .943 87.80 ('I') ~ 7 600 " 16,559.09 13,897.91 13,429.19 .966 83.92 8 700 " 16,281.30 13,328.90 13,289.70 .997 81.86 9 800 " 16,753.55 13,236.63 13,209.24 .997 79.00 10 1000 "· .16, 687.91 12,783.43 12,611.00 .986 76.29

* Average of 5 samples - 13 7-

and the channel ratios were determined. The appropriate volumes of chloroform were then added to bring the final volumes to 12 ml. The readings of analyzed samples used to evaluate the quench correction curve are shown in Table 27.

The detection efficiency was calculated as follows: CPM quenched/CPM unquenched X 100 = Detection efficiency. The channel ratios were calculated as channel 3/channel 2 for the

quenched samples. Here is an example of the calculation:

20, 017 •5° CPM Ch. 3 = 0.69 channel ratio 29,010.14 CPM Ch. 2

29,010.74 CPM Ch. 2 quenched (at 200 pl of CHC1 ) X 100 ______3;;::...._ __ = 92.36% 31,407.03 CPM Ch. 2 not quenched

of efficiency.

The quench correction curve was then plotted as detection efficiency versus channel ratio (Fig. 25 ). From the eXperimental quench correc- tion curves another curve was calculated to match them closely. This curve was obtained from the following equation: 2 3 Y = 120.46645 - 113.55144 x +191.55065 x - 117.67482 x

In the final scintillation analysis, each ashed sample was taken up in 1 ml of 0.5 N HCl and transferred to a glass liquid-scintillation vial. Each 50 ml beaker was rinsed with a second aliquot of 1 ml of

0.5 N RCl. Finally, 13 ml of PCS solubilizer were added which formed a clear homogenous solution without colour quenching effect. Each - 138 -

scintillation vial was then capped, shaken and let stand for 24 hours

before analysis. In the scintillation printout the amount of radio-

activity of each sample was expressed in counts per minute (CPM)

which were converted in desintegrations per minute (DPM) as shown

in the example below obtained from sample 12 of block 5, root bark

analyzed on June 19, 1975.

a) Determine channel ratio

Ch~ 3 126593~75 a c .6038 Ch. 2 209660.00

b) Determine detection efficiency from Fig. 24 (95.8%) c) Use formula to determine DPM: *

log M • log No~ [(.4343) (.0042) (t)] 10 10 where: No = channel 2 CPM; M = DPM; .0042 =

decay constant for ~ 5Ca; t = time in days from the reference date; .4343 = 1/2.303 to convert natural logarithms to base 10 logarithms.

This formula was simplified and modified to incorporate the

counting efficiency factor as follows: · Ch. 2 CPM M 10 (.001832746 X days) X • . X 100) = 95 8 . 209660 M • 10 (.001832746 X 79) X ( • X 100) 95 8 M • 316869 DPM

* Radiotracer Methodology in Biological Science, 1965 By Wang and 0 Willis Prentice Hall Inc. Toronto or Eng1ewood Cliffs, New Jersey p. 27 - 139 -

lQUENCH CORRECTIONCURVE

> 0z w I~- 'u.. tu.. !w lz 1_0 ~~ !w•1- !c '

---[Calculated curve ----[Average --[@46pCi --[@ 23pCi /Ch = Scintill~tor,Channet

r.3 f.4 j.5 [.6 I Ch3:Ch-2 pig. 25 Quench Correction Curve - 140 -

Statistical layout and treatment of the data

The statistical design was a 2 x 2 x 4 factorial with 6 blocks.

The experimental unit consisted of 2 trees per treatment combination.

There were 2 4 ~Ca levels (23 ~ Ci and 46 ~ Ci), 2 cultivars (Spartan and Harrold Red Delicious) and 4 rootstocks (M26, M7, MM106 and MMlll).

The trees of blocks II, IV and VI were treated with 6-Benzyladenine plus gibberellic acid as will be explained in 3.2.2.

Since most of the DPM numbers were very large and since 30 para- meters had to be analyzed it became necessary to use the computer

facilities of the Statistical Research Service of Ottawa. Here is

the list of all the parameters which were analyzed with respect to

growth regulator treatments (discussed in 3.3.2), ~ 5 calcium concentra-

tions, cultivars and rootstocks.

A. Between the trees (~ 5 Ca uptake by the whole tree) symbol

1. Hca uptake in general (initial DPM-final DPM) CAS 1 2. ~tsca uptake per shoot length removed (cm) CS/S 1 2 3. ~tsca uptake per 1-eaf area removed (cm ) CS/T 4. *"ea uptake per weight of removed tissuel (gm) CS/W

5. uca uptake per number of removed 1 shoots CS/N

B. Within each tree. Each of the following 25 parameters

were measured for each of 1) 45Ca uptake by the young

shoots; 2) 45Ca uptake by the old leaves; 3) 45Ca

1 before the start of the 45Ca study. - 141 -

uptake by the high bark; 4) ~tsea uptake by the low bark; and

5) ~tsea uptake by the root bark symbol

1. ~tsca uptake (total) eAU 1 2. 45ea uptake per shoot length removed eA/S

5 1 2 3. 4 ea uptake per leaf area removed (cm ) CA/T

4. 4 sca uptake per weight of removed1 tissue (g) eA/W

5. 45ea uptake per number of removed1 shoots CA/N

6. ~tsea uptake per fresh weight (g) CA/F

7. 45ea uptake per fresh weight x shoot length e/FS

8. 45Ca uptake per fresh weight x leaf area e/FT 1 9. 45ea uptake per fresh weight x weight of removed tissue e/FW 1 10. ~tsca uptake per fresh weight x number of removed shoots e/FN

11. 45Ca uptake per ash weight (mg) CA/A

12. 45ea uptake per ash weight x shoot length e/AS

13. 45ea uptake per ash weight x leaf area C/AT

14. 45ea uptake per ash weight x weight of removed1 tissue e/AW

15. 45Ca uptake per uptake per ash weight x number of

removed1 shoots 2 16. 45 e~ uptake per area of tissue (cm ) CA/R 17. 45Ca uptake per area of tissue x shoot length e/RS

18. 45Ca uptake per area of tissue x leaf area C/RT

19. 45Ca uptake per area of tissue x weight of removed1

tissue C/R~l

20. 45ea uptake per area of tissue x number of removed1

shoots C/RN 1 before the start of the 45Ca study. - 142 -

symbol 21. 45ca uptake per dry weight. (mg) CA/D

22. '+Sea uptake per dry weight x shoot length · C/DS

23. '+Sea uptake per dry weight x leaf area C/DT 1 24. 45ca uptake per dry weight x weight of removed tissue C/DW

25. '+ 5ca uptake per dry weight x number of removed1 shoots C/DN

From scattered. diagrams it was decided that geometric means along with logarithmic transformations had to be used because of the improved normality of the distribution. From these_ geometric means

I was able to transform back to actual DPM by using antilogarithms.

3.2.1.B. Results

Means of 98.6 and 94.4% of the expected radioactivity were detected in the nutrient solution of the trees treated with 23 and 46 p Ci respectively. After their 21 days holding period in the isotopic Ca solution the trees treated with 23 p Ci had absorbed 43.3% of the

45Ca while those treated with 46 p Ci had absorbed 41.9% (Table 28).

There were no statistically significant rootstock and cultivar effects on the total uptake of 45Ca per tree although the rootstocks M26,

MMlll and the cultivar Spartan tended to have a higher total absorption of the isotopic Ca (Tables 29 and 30). On the other hand the trees which had M7 as rootstock or those which bad H.R. Delicious as cultivar absorbed significantly more of the full nutrient solution than the others

(Table 3l)but geometric means were used these differences were invali- dated (appendix Table IA). No significant cultivar-rootsotck interaction 1 before the start of the '+ 5ca study - 143 -

effect was found in this experiment except in the case of total 4 sea

uptake by the tree (Tables 29 and 32).

Concerning the redistribution of ~sea in the tree it was found

that the ~sea levels, the cultivars and the rootstocks exerted a signi-

ficant influence especially on the top portion of the tree above the

graft union (Table 32}. From the bottom to the top of the tree there

was a significant decrease in the revel of 45Ca from tissue to tissue

(Fig. 26).

The general 45ea distribution pattern throughout the tree shows . that in a upward direction in the tree the decrease in the amount of

\Sea in the tissues was very pronounced below the graft union but

in the scion part this decrease was not so sharp (Fig. 26 and 27).

In general, the lower level of ~ 5 ea more or less paralleled that of the

higher level and was roughly somewhat less than half of it (Fig. 27).

The cultivar H.R. Delicious has consistently caused a lower

absorption of ~ 5 Ca than Spartan. This absorption gradient was

significant at P • .OS or P • .01 in the tissues above the graft

/Union and was particularly high in the young shoots tissue (Figs. 29

and 30). From the root to the tree top there was an increasing

difference in the percentage of ~sea content between Spartan and

H.R. Delicious. It was inversely proportional to the distance from

the root system. The greater the distance the more was the difference

between the two cultivars (Fig. 30). 0 - 144 -

Within each rootstock the distribution pattern of ~ 5 ea did not correspond to the dwarfing potential of the rootstocks. The trees which had M26, M7 and MM106 as rootstocks accumulated statistically

the same amount, i.e. 3.3, 2.8 and 2.4% of ~sea in their young shoots while those which had MMlll accumulated significantly less, i.e., only 0.84% of it in their young shoots (Fig. 28 and appendix Table IX). The same phenomenon was observed for the old leaves and the high bark tissues. However there Was no significant difference among the four rootstocks for the low bark and the rootbark tissues (ibidem).

The rootstock MMlll was the least efficient in facilitating the

'sea transfer into the uppermost sections of the tree (Fig. 28 and appen­ dix Tables II to VI). TABLE 28. Recuperatioit.of the radiocalcium per tree (arithmetic mean)

Concentration Theoretical Amount % Amount of % % uptake 1 of ini2ial ( ll Ci ) radioactivity radioactivity recuperated 45ca absorbed absorbed of expected (DPM) (DPM) (DPM) initial amount

23 51,060,000 50,347,500 98.6 21,807,500 35.0 43.3

46 102,120,000 96,407,500 94.4 40,130,100 65.0 41.9

~ ~ 1 6 based on the fact that 1 ~ Ci • 2.22 x 10 DPM

2 overall mean of no. of DPM found in 2500 ml of radioactive solution at the beginning of the experiment ·

0 0 ~· TABLE 29. Levels of significance between the radiocalcium uptake of the

whole tree and four treatments (arithmetic means from appendix 1 Table I)

Source of 2 variation CAU 1 BG ** Block/BG ** Ca * c * R ** BG x Ca * BG x R ** Ca x C * Ca x R * CxR *

1vertical symbols: BG = Benzyladenine + gibberellic acid;

Ca • ' 5ca levels; C = cultivars;

R • rootstocks

2 horizontal symbols: CAU a Calcium uptake (initial - final DPMs) - 147-

TABLE 30. Total uptake of radiocalcium per tree with respect to rootstocks, 1 . cultivars and radiocalcium levels (arithmetic means from appendix

Table I) rootstocks Uptake/sample Uptake/tree % absorbed (DMP/ml) (DPM/2500ml) 2 M26 14020 35,050,000 28.3 a

M~Ull 12730 31,825,000 25.7 ab

MM106 11538 28,845,000 23.3 b

M7 11272 28,180,000 b cultivars

Spartan 11572 33,022,500 53.3 a

H.R. Delicious 13209 28,930,000 46.7 b

45 Ca levels

23 ll Ci 8723 21,807,500 35.0 a

46 ll Ci 16052 40,130,000 65. b growth regulators

0 ppm 14695 36,737,500 59.3 a

BA 2000 ppm + 10085 25,212,500 40.7 b GA 500 ppm

1 from amount initial DPMs - amount of final DPMS (Before the experiment -

After 21 days of absorption)

2 means followed by the same letter are not significantly different at

P = .05 according to the Duncan's new multiple - range test. - 148

1 TABLE 31. Uptake of the full.nutrient solution per tree with respect

to rootstocks, cultivars and nutrient levels (arithmetic

mean)

Rootstock uptake (g=ml) 2 M 7 35.9 a

MM'l06 32.3 b

M 26 31.3 b

MM 111 30.2 b

Cultivar

H.R. Delicious 32.7 a

Spartan 29.1 b

.ltSca level

46 1J Ci 32.7 a

23 1J Ci 32.1 a

1 . Difference in weight between tree pot weight prior to and after the

experiment. 2 . Means followed by the same letter are not significantly different

at the 5% probability level according to Duncan's new multiple-range

test. - 149 -

TABLE 32. Levels of significance between the radiocalcium uptake at five

locations of the tree and four treatments (geometric means from

ap~endix Tables II to VI)

Source of variation YS OL HB LB 1 BG * Block/BG ** * ** ** * ea ** ** ** ** ** e ** * * R ** ** ** BG x ea * * BG X e

BG X R ea xC Ca X R * c X R H;igher interactions

1 Y~!~!£~!-~~~2!~: BG = Benzyladenine + gibberellic acid; 45 ea = ea levels; e = cultivars; R = rootstocks 2 ~~!!~2~~~!-~~~2!~: YS =young shoots; OL =old leaves;

HB = high bark; LB = low bark;

RB .. root bark. - 150 -

_d = Confidence interval at p = .01

95

" ~ 90 1,400,000 85 \... h = Confidence interval ot p = .05 80 .. \ 1.200,000 75

70

·~ot.-l,i 65 1,000,000 I 60 •I -. I I I 55 ·~=. I -0 I '· 800,000 50 .~ I .. Q) I 0~ !!: I 45 .. » I .... I '• 'C t: ....0 40 600,000 c 0 ::I 36 E ...... 0 ...... ~ 0 30 ~ I a.. I 0 400,000 I 2.5 I I l I 20 'I . . I IS 200,000 I .· I .,... I 10 100,000 I I . 5 50,000 I 25,000 I root low high old young bark bark bark leaves llhoots

Fig. 26 Distribution of radiocalcium throughout the tree (Geometric

means from appendix table VII; Confidence intervals from

table XXI; confidence intervals from appendix table XX). - 151 -

·- :::SI g n1'f' .can t d'ffI erence at p ;:I •0

**,__

l = 23 1-1 c; ~ .1~200,000)- H=46 iJ c i

....--./ --·

,_ . ' 1,.ooo,ooa . c 0 ·-c :::t . 800,000 - .... -..b .--- **!"- "' ; 1 .c .·l -tJ) ... j ~ -~ soo.ooo - ...,... . 't) Cl' , .,E . i :E I 0. 400,000 - ! 0 .. , r- .· 'l .. l 200,00 0 l - I • ,_ *r-- ·. too.oo·o •' * • .. 50,00 0 - 111 * 25,000 - .., I dl m J L H L H L H L H L H root low. high ol.d young bark bark bark leaves shoots

Fig. 27 Distribution at two levels of radiocalcium throughout the

tree (Geometric means from the appendix table VIII). - 152 - t.eoo.oop = CON FIOENCE INTERVAL A l p = . 05

... lt· • • .. p •• 01 ,. RB: ROOI BARK LB "LOW BARK . HB =HIGH BARK

OL=OLD LEAVES 1.2oo.ooo ... YS=VOUNG SHOOTS- 1- .. r.ooo.ooo -

eoo,ooo .. .s::- C> . ·- ' T ,.! r- I ,.. " I ·~ I '1:1 Goo.o oo - i i . "'e ..... i- :E A. .... I HI i 0 I I 400o000 ~ ' I l

&oo,ooo ,..

1- 100,00 0 ·- rr-r 50,000 Hrrf±lrql 2!!·000 ~~ ~ Ff~g,-

M26 M7 MM 106 M Milt

Fig. 28 Distribution of ~ 5 calcium within each rootstock (Geometric

means from appendix table IX; Confidence intervals from

appendix tables XVI to XX). - 153 -

! Q· 1,600,000- DISTRIBUTION OF 45CALCIUM IN THE FIVE TREE PARTS FOR BOTH CULTIVARS SPARTAN AND "':J HARROLD RED DELICIOUS :§0 (GEOMETRIC MEANS & DRY WEIGHT a; BASIS) a 1.400,000- a: ::i + ..,c lo ~ ...... IQ a. en· 1,200,000- \. ... '#. 0 .....0

1,000,000- - 36

1- N.S. :!: 0.. a

800,000 - 27

... .~ .. ,-_' 600,000

.. 18

400,000-

- 9 200,000 - N.S. 4.5 .. 100,000 2.25 ; 50,000 "' 25,000 ___ []] ~- ___ lli~ 1' s D s D S D s D s D root low high old young bark bark bark leaves shoots

Fig. 29 Distribution of radiocalcium within each cultivar and each

tissue (Geometric means from appendix table X ; Confidence intervals from Tables XVI to XXI). - 154 -

3.2.1.C. Dfscussion

The counts for ~sea (DPM/g dry weight) obtained in this experiment were extremely high compared to those obtained by Millikan (1971), and Stebbins and Dewey (1972) in apple tree tissues for similar con­ centrations of radio-calcium. For example, Stebbins and Dewey (1972) found in the young leaves of their apple trees· approximately 100 times less ~ 5ea than we did. However, they kept adding deionized water in their nutrient solution to make up for the losses caused by plant trans­ piration and to maintain a constant volume of liquid of 300 ml in each tree container. In so doing they considerably diluted their solution and weakened the concentration of ~sea in every pot. Moreover, their trees absorbed the solution of ~ 5ea during 7 days only while our trees stood for 21 days in the isotopic solution.

The recuperation of the radiocalcium was quite good at both levels of 4 sca and one can easily figure out that only a very small portion, i.e.,. 0.299% of the radioactivity was found in the tissue samples (Table 28 and appendix Tables II to VI). The most dwarfing, M26 root­ stock, caused the greatest total uptake of ~ 5 ea per tree. On the other hand, when the results were expressed in arithmetic means, MMlll, the least dwarfing one, was not statistically different from M26 and, since

MMlll could not translocate • 5ea as well as the other rootstocks, no relation seems to exist between the ability of a rootstock to absorb

~ 5 Ca and its ability to redistribute it within the tree (Table 30 and

Fig. 28). Similarly, when the results were expressed in arithmetic means, - 155 -

M 7 permitted a significantly greater uptake of the full nutrient solution and was by no means responsible for a greater uptake or redistribution of 45Ca. Its metabolic potential does not reflect its capacity to convey

the isotope within the plant (ibidem).

The cultivar Spartan which has always conveyed 45Ca into the various

tree parts more efficiently than Harrold Red Delicious was also signi­ ficantly better in favouring 45Ca uptake by the whole tree, even though

the trees which were topworked with Spartan absorbed less full nutrient

solution (Tables 30 and 31). Therefore, the cultivar effect appears

greater than the rootstock effect in this experiment. Hansen (1965) stated that the leaf content in minerals and particularly in Ca showed

a greater scion than rootstock effect. · Similarly K8ksal (1973) found

that the influence of the varieties. Cox's Orange Pippin, Jonathan

and Red Boskoop on mineral composition (N. P, K, Ca and Mg) of the

leaves was more pronounced than that of the rootstocks M7, M9, MMlll

or M9 interstem.

Of all the parameters listed in pp. 140, 141 and 142 it was decided

that 45Ca uptake on a dry weight basis (CA/D) was the one which repre­ sented best the real uptake of calcium by the apple trees. All criteria concerned with tree vigour, such as area of removed tissue, total

leaf area, shoot length and weight of removed shoots, were not chosen

because vigour was considered not accurate enough to take into account

the variation which exists from tree to tree. Similarly, the ash weight basis referring all measurements to only the mineral content of - 156 -

I I I • [65i S=SPARTAN 1 so- \ D "'1 HARROLD RED DELICIOUS - I .-- 155;... .-:--·- ' -- 1 --. c:::.::: . . \50------r~-- . . .• -·-r-.::.....NS ::: ---- '~5j I •.. r.--.1*-·- ... \ 14o-, :::: t---~. I j35;... %,

I!3o~ I

I \25l-.

/20t--.

115r

\ 5r--

·-··-~-··-~- iD 1 s 1 -1 S JD \S ID l.~ ID --L~~-1'?. ~:·· I ROOT_ LOW jHIGH IQLD jYOUNG IBARK IBARK SHOOTS 1BARK jLEAVES

Fig. 30 Differences between the cultivars in the percentage of

radiocalcium uptake within each tissue (Geometric means/mg

dry weight). - 157 -

the plant was not found good enough since the important plant organic matter was ignored. Expressing the uptake of ~ 5 Ca on a fresh weight basis was rejected since fresh weight includes constitutional water which is derived from very complexe physiological processes difficult to account for. The area of the tissue sample CA/R could have been used and, in fact, gave a statistical analysis similar to that of the dry weight basis (Appendix Tables XI to XV). . However, it is a less commonly used way of expressing results and it does not take into account one dimension of the tissue which is its thickness.

Oberly and Paling (1978) have shown that the dwarfing of apple rootstocks was not due to a reduced movement of nutrients acorss the graft union. However they did mention that certain tissues or rootstocks may impart the level of a given element. In the present study I failed to prove that a tissue such as that of the graft union could slow down theCa movement (Figs. 26 and 27).since I had no cam- parison with ungrafted trees. However, my results seem to indicate that the graft union may interfere with 45Ca uptake since there was a sharp decrease in the uptake of ~ 5 Ca above the graft (Fig. 26). Tukey (1964) demonstrated that, although 32 P could move freely across graft unions of tomato plants, the movement of 45Ca was very strongly slowed down or stopped by the graft union. It has been recognized that callus formations such as those caused by grafting will obstruct, at least temporarily the sieve tubes of a plant (Camefort 1972) and cause a suberization of bundle sheath cells which ahs a restrictive effect of Ca uptake (Fergusson, 1979). Most of this interference should logically - 158 -

take place in the xylem tissue since, according to Wieneke (1979), the ascending of Ca primarily occurs there. In that tissue the thickening of the cellulose could constitute a barrier to theacropetal transport of Ca (Fergusson, 1979). It is for this reason that K8ksal (1973) reported that interstems lowered the Ca and Mg content of the leaves, notably with the cultivar R. Boskoop.

The requirements of Spartan apple trees for Ca was much greater than that of Harrold Red Delicious trees. Likewise, the fruits of the cultivars which are susceptible to calcium-related disorders usually need higher levels of Ca in their tissues. In a private communication

Faust (1974) mentioned that the cultivar Golden Delicious had a higher capacity for Ca uptake than several other cultivars he had tested.

This was confirmed by unpublished work conducted by Mason (1967 and

1973) which revealed that Red Delicious on MM106 was very poor in ab­ sorbing Ca in its leaves while Golden Delicious was quite excellent in this respect. Of course Red Delicious is much less susceptible to bitter pit than is Golden Delicious. In Mason's study Spartan and Winesap requi­ rements for Ca were about half way between these two extremes. Similarly K8ksal (1973) reported that Cox o. P. was very inefficient in absorbing Ca in its leaves as compared to Jonathan and Red Boskoop and, in fact, is much less susceptible to Ca induced disorders than these two.

Oberly and Poling (1978) have also discovered that the Red Delicious leaves were higher in N, P, K, Fe and B but lower in Ca than Mcintosh regardless of the rootstock. It has been shown in Table 30 that the difference in 45Ca content between Spartan and H.R. Delicious is gradually - 159 - more pronounced from the bottom to the top of the tree. This phenomenon may largely be explained by the fact that the ea content of a tissue is associated with its specific metabolic activities and relates directly to transpiration (Stebbins and Dewey, 1972) and respiration (Bangerth et al. 1972; Faus·t and Shear, 1972).

As regards to rootstocks I did not discover that their ability to absorb Ca corresponded to the degree of compactness they confer to an apple tree. A number of other workers (Oberly and Poling, 1978; Lockard,

1976; Whitfield, 1963; England, 1971; Mason, 1967 and 1973) agree with . this conclusion. In the rootstocks tested by England (1971) it was found that M26 was significantly superior to M7, MM106 and MMlll. in enhancing the accumulation of Ca in the fruits of ; however, in the fruits of Wellspur it was second to M7. Even though there was no significant difference among the rootstocks in their ability to absorb

~ 5 Ca some findings reported in the thesis suggest that, since M26 caused a high accumulation of ~ 5 ea into the uppermost section of the tree, it might be a rootstock which could indirectly help in reducing the incidence of breakdown on Spartan apples in increasing their Ca content.

M9 is another dwarfing rootstock which has displayed· evidence of g0 od performance concerning the uptake of ea. Mason (1967 and 1968) in an unpublished sand culture experiment found that, among 4 size controlling rootstocks, M9 resulted in the highest content of ea in Delicious fruits and leaves. Whitfield (1963) reached the same conclusion regarding the cultivar Cox's O.P. grafted onto 4 compact rootstocks and I<8~al (1973) did it also for the cultivars Cox's O.P., Jonathan and R. Boskoop grafted - 160 -

onto 3 compact rootstocks. Surprisingly enough both M9 and M26 are known to be dwarfing to approximately the same degree. On the other hand out of the size controlling rootstocks M9, N26, and M7, this latter one caused the lowest content of Ca (K8ksal, 1973). From my findings, and from those of others mentioned above, it would appear that the rootstocks which are very dwarfing or which are known to induce precocity such as M9, M26 and MM106 are the most reliable ones to transport Ca to the top of the tree.

The only weak rootstock•cultivar interaction found in this experiment would suggest that in the uptake of 45Ca by the whole tree, the cultivar concerned was unable to make the rootstock overcome any Ca imbalance resulting from the rootstock effect. Other researchers such as

Eaton and Meehan(l972) and Whitfield (1963) found a few scion-rootstock interactions but in general no interaction was found between cultivar and rootstock (ibidem), as was found in my experiment.

The trees grown in the greenhouse for this experiment all had a very lush growth and were all fairly uniform regardless of their genetic vigour. This may explain why no significant difference was found in the

5 ,. Ca uptake at the low bark and the root bark levels. Below the graft union all trees behaved more or less the same since 45Ca was allowed to move very freely in the tissues of the rootstock. However, in the scion part where high photosynthetic, respiratory and transpiratory rates occur there were specific demands for Ca depending on the genetic make-up of the scion, the location on the tree top or the function of a given organ.

Bukovac et al. (1958) and K8ksal (1973) also failed to find great - 161 -

differences in the rate of ~ 5 Ca uptake of various rootstocks below their

graft union.

Cultural and environmental factors

In the light· of what was learned from this experiment it might be preferable for the apple grower to use M26 and MM106 for the cultivar

Spartan. These rootstocks seem to-lend themselves to better transport of Ca in the tree top. As regards M9 a few researchers (Mason, 1967 and 1973; Eaton and Meehan, 1972) found that it could also favour the

redistribution of Ca into the Spartan cultivar.

Since the graft union might perhaps temporarily interfere with the

Ca uptake it might be wise to avoid the use of interstocks with Spartan as the tree top. K8ksal (1973) found that they were detrimental to Ca uptake in the case of Cox's O.P., Jonathan and R. Boskoop.

Large quantities of Ca are usually translocated in the bark and the phloem tissues (Stebbins, 1972). Therefore winter injury of those tissues could greatly impair their transport of Ca. -From a practical point of view

"that kind of injury could be critical in the case of Spartan apple trees.

In my experiment •sea at both concentrations 23 and 46 ~ Ci was readily absorbed by the trees through their root system. In the field increasing the level of Ca in the leaves and fruits of apple trees by means of soil applications is generally unsuccessful (Oberly and Poling,

1978). However according to Childers {1978) this can be achieved by - 162 -

incorporating lime in the orchard soil, bringing the pH to a proper level and creating good soil texture and structure.··

3.2.2 Effect of GA and BA treatments on the absorption of tadiocalcium

3.2.2.A. Materials and methods

Immediately after they were decapitated to 3 leaves the trees of blocks II, IV and VI were all treated with 6-Benzyladenine (BA) at

2000 ppm. One and two days later the same trees were treated with GA3l.: at 500 ppm (Fig. 26). The application of these growth regulators consisted in dabbing one drop of BA or GA3 solution with a tiny paint brush at the axil of each of the 3 leaves left on the trees headed back as shown in

Fig. 26. The purpose of these treatments was to promote the rapid growth of the latent bud located at each leaf axil in order to favour the absorption of ~ 5Ca which has a tendency to accumulate in the fast growing tissues, as was pointed out by Stebbins and Dewey (1972). The BA solution was prepared by dissolving 200 mg of BA (SD 4901) powder in a solution of 10 ml of 2% KOH. In order to make the solution more penetrating as proposed by Broome and Zimmerman (1976} 5 ml of DMSO (dimethylsulphoxide) and 1 ml of the spreader Tween 20 oil were added along with tepid distilled water to make up a total volume of 100 ml. The GA solution was prepared by dissolving 1/2 tablet of "Actival GA" in one litre of

"Actival GA" or Gibberellic acid /13 sold by Plant Protection Ltd., Fern­ herst, Haslemere, Surrey, England and made by Agricultural Division of Imperial Chemical Ltd., England (each tablet contained 1 gram of active ingredient). - 163 -

distilled water.

3.2.2.B Results

Contrary to what was expected the buds treated with the growth regulators produced shoots which were significantly less developed in terms of weight and leaf surface than the ones which were not treated

{Table 33).

The total uptake of \Sea per tree was significantly diminished by the growth regulator treatments {Table 29 and appendix Tables I and IA).

The transport of \ 5Ca to the young shoots was also significantly impaired by the BA and GA applications. The other tissues were not significantly affected in their absorption of the isotope {Table 32 and appendix Table

II) • - 164 -

TABLE 33. Effect of growth. regulators on the development of the young

shoots (arithmetic means)

Oppm BA GA 2000 + 500 ppm leaf leaf area weight. area weight (cm2) (g) (cm2)

Block I 34.30 3.05 Block II 31.90 2.56

Block III 38.60 2.13 Block IV 34.30 2~48

Block V 52.13 3.48 Block VI 28.34 2.91 mean 1 41.68 2.87 31.51 2.65

1 The reduction caused by the treatment is 3.98% in weight and 13.89% in area. - 165 -

3.2.2.C Discussion

This experiment was initiated in an attempt to cause an artificial accumulation of 45Ca in fast growing plant tips, as suggested by

Stebbins and Dewey (1972) and Millikan (1971). The growth regulator treatment was used to stimulate the growth and create a sink for Ca.

Since, on the contrary, the growth of the young shoots was decreased by

3.98% in weight and by 13.89% in leaf area the grwoth regulators at the concentration used must have decreased the transpiration, the respiration and the photosynthesis of the young shoots. In fact, slight symptoms of phytotoxicity were observed in a few cases.

While the movement of 45Ca into mature leaves of apple seedlings was increased with sprays of kinetin and N-6-benzyladenine (Shear and

Faust, 1971) no such effect was observed in this experiment as the growth regulators did not significantly affect the 45Ca uptake of the tissues other than that of the young shoots (Table 31). Of course, the method of application and the concentration of 6-BA described here was much different than that used by Shear and Faust.

Not only did the treatment decrease the transport of 45Ca to the plant tips but reduced the uptake of this element by the entire tree

(Table 28). These results are not surprising in that Stebbins (1972) reported that gibberellic acid in some plants inhibited the trans­ location of Ca into fruits. Moreover, since damiriozide (DASH) has been reported to produce effects opposite to that of GA (Scbumacher, 1973;

Ryugo and Sachs, 1969; Luckwill, 1968) it seems logical to observe that - 166 -

GA interferes with Ca uptake because SADH has been reported to increase the level of foliar Ca on apple trees (Himelrick et al. 1976). As regards benzyladenine, Broome and Zimmerman (1976) demonstrated that whenever it was used in the conditions above described, it caused consi­ derable bud development after 21 days on crabapple trees. This growth regulator retarded senescence and over-stimulated the chloroplasts in cabbage (Dennis et al. 1967). Whether the action of BA is boosted in a sort of a synergism by GA or whether it is inhibited by it has yet to be elucidated. The results obtained in this experiment lend validity to the latter hypothesis.

Cultural and environmental factors

In the light of what was learned regarding the use of BA and GA on young apple trees the apple grower should know that these growth regulators may slow down the rate of Ca uptake and therefore indirectly influence the breakdown of Spartan apples in storage. On the other hand, the use of SADH under specific conditions should normally create the opposite effect. - 167 -

4. StTMHARY AND CONCLUSIONS

In a first experiment Spartan apples picked at their optimum level

of maturity from comparable orchards in Quebec and British Columbia

were pre-sized diametrically into small, medium, large and extra large

categories and rapidly placed in cold storage. The apples from Quebec

were comprised of 5 bushels of each of the first three categories while

those from British Columbia consisted of 5 bushels of each of the last

three groups. While most of the fruits were examined for breakdown

development after 8 1/2 months in cold storage, peel and flesh tissues

of individual apples from ~ach category were analyzed for total N, P, K,

Ca, Mg and Zn. Firmness, percentage of red colour, specific gravity,

moisture content, titratab.le acidity and percentage of soluble solids

along with and H release rates were also determined in individual co2 c2 4 fruits in every category.

In the present study it has been shown that in order to minimize

Spartan breakdown incidence, the fruit diameter had to measure less than

7 cm. Lidster et al. (1974) stated it had to be no greater than 5.8 cm. ~ ~tkis was p~eviously sftewa 9y tiester e~ ~6. (1974): On the other hand, the biggest and/or the heaviest fruits were associated with. a high incidence

of breakdown development in cold storage. This was confirmed by several authors (Mason et al. 1973; Lidster et al. 1940; Chace 1962; Martin et al.

1965; Bernstein and Marshal! 1942 and Hall and Cellier 1966). That the

B.C. fruits were more affected by breakdown than the Quebec ones may partly

be explained by their larger size. As regards fruit weight no relationship

between mass and hreakdown incidence seems to have been reported in the

literature. - 168 -

Peel ltg which was very high in the B.C: fruit appears to be a key factor in predicting the development of Spartan breakdown in cold sto­

rage. Brooks and Fisher (1918), Sharples (1971), lUrth et al. (1970)

and Das (1971) provided evidence that excessive Mg could provoke break­

down related disorders in the apples of various cultivars. Although

flesh Mg proved to be, in this study, a reliable but much less potent

predictor of Spartan breakdown it was found insignificant by Lidster et al. (1975). Mg, which is lacking in both Quebec and B.C. soils may, whenever supplied adequately, increase Ca uptake and therefore

help reduce breakdown (Shear, 1974).

Both flesh and peel K levels were very high in the B.C. fruits or in the largest ones. Along with Lidster et al. (1975) I found that flesh K was an excellent predictor of Spartan breakdown. Based on the

content of the small apples from Quebec (Table 16) flesh K should be less

than 788 ppm (% f. wt) in order to minimize Spartan breakdown. This level

may be harder to obtain in B.C. as the orchard soils of the Okanagan

Valley are naturally very high in that element while those of Quebec are

generally low (Swales, 1971; Granger, 1974).

The P content of the B.C. Spartan apples was twice as high as the level found in Quebec apples. Flesh P was an acceptable predictor of

breakdown. Garman and Mathis (1956) found that high content of P in

the fruit was associated with the prevalence of 'Baldwin spot'.

Likewise high levels of P in the experimental apples were associated with more breakdown development. - 169 -

While no location effect was observed in the Ca content of the fruit samples, the largest apples contained obviously much less Ca than the other ones. Nonetheless the predictive value of the important Ca · element was emphasized. It must be noted that the Quebec Spartan apples were grown in a Ca rich soil while the B.C. ones were grown in land where Ca was deficient. In agreement with Mason and Macdougald (1974);

Mason et al. (197S)and Lidster et at. (1975) I found a negative correlation between the Ca level and breakdown development. However~ I recognized that ratios such as K + Mg + P to Ca or K + Mg to Ca, could relate more properly to breakdown than Ca by itself. Garman and Mathis 1956 arrived at the same conclusion concerning a different cultivar.

Firmness at harvest was negatively correlated to breakdown and had a high predictive value. Since it can easily be measured by apple growers it could certainly help them grow good keeping quality fruits.

On the other hand, juice acidity, which was significantly related to breakdown, is somewhat more difficult to gauge, but could still be measured fairly quickly and was a help in detecting some susceptibility of apples to breakdown and thus to indicate their K content (Wilkinson

1958; Wood and Looney 1977).

On a per unit weight basis no correlation between the respiration rates of apples and the development of breakdown could be found, as discovered by Kawamata (1978) and Looney (1977). However, on a per fruit basis a significant negative correlation appeared. Expressed in this manner the Spartan breakdown susceptibility may relate more clearly to fruit - 170 - respiration, as stated by Looney (1977) and explains partly the high

K and high acidity content of the B.e. apples.

As regards the ethylene production rate, the correlation to break­ down was negative on a unit weight basis; however, on a per fruit basis it was both positive and higher. Moreover, when the e H release rate 2 4 was expressed on a per fruit basis an inverse relationship to ea was

revealed, similar to that discover~d by Faust (1974).

In a second experiment the clonal apple rootstocks M 26, M 7,

MM 106 and MM 111 grafted to 'Spartan' and 'Delicious' were planted

in pots of sand. After a period of growth the trees were depotted, pruned to the 3 basal ieaves of the scion cultivar and the roots were immersed in a nutrient solution containing ~sea. Gibberellic acid plus 6-Benzyladenine applied to the axilary buds of these leaves

failed to promote their growth and interferred with ~sea uptake. This confirmed the observation that gibberellic acid in some plants inhi- bited the translocation of ea into fruits (Stebbins, 1972). Since damino­

zide has been reported to produce effects opposite to that of GA (Schu­ macher, 1973; Ryugo and Sachs, 1969; Luckwill, 1968) it was not unusual to observe that GA interferred with ea uptake because daminozide has in turn been reported to increase the level of fol1ar Ca on apple trees (Himelrick et al. 1976).

The cultivar Spartan consistantly conveyed greater amounts of

4 sea into various parts of the tree than did Harrold Red Delicious. - 17 1-

This indicates that Spartan's requirements for Ca are higher than those of Harrold Red Delicious. Similarly, the fruits of the cultivars which are susceptible to calcitim-related disorders usually need higher levels of Cain their tissues (Faust, 1974; Mason 1967 and 1973; Kl:Jksal, 1973).

Interestingly enough, this avidity of Spartan for Ca gradually became more pronounced from the bottom to the tree top. That may partly explain why Spartan apples which need great amounts of Ca may develop a susceptibility to breakdown when the Ca supply is not adequate.

In spite of the fact that no great rootstock effect was observed it appeared clearly that the most vigorous rootstock was the least

~5 . efficient in conveying Ca to the uppermost section of the tree.

This was previously observed by other researchers (Mason, 1967 and 1978;

Whitfie1d, 1963; Kl:Jksal, 1973) with cultivars other than Spartan. - 17 2-

5. CONTRIBUTIONS TO ORIGINAL KNOH"LEDGE

As far as the author is aware, the research reported herein contains the following contributions to original knowledge.

1. Analysis of the chemical constituents< and physical properties of

Spartan apples permitted, for the first time, the establishment of

criteria suitable for determining the susceptibility of these

fruits to develop breakdown.

2. With regard to breakdown development in Spartan apples, together

with the practical implications of this process, new ways of expres­

sing and H release rates were advanced. co 2 c2 4

3. The specific requirements of the Spartan scion cultivar for Ca and

its ability to facilitate the movement of Ca within the tree were

spelled out for the first time.

4. The inhibiting action of the GA and BA growth regulators on Ca

transport into the scion portion of a Spartan apple tree was demons­

trated for the first time.

5. The results of this dissertation should both facilitate future

research in apple physiology and assist the grower in producing

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0 APPENDIX TABLES TABLE I. AOV of the calcium uptake by the whole tree CAU (arithmetic means) Source of DF Sum of Mean square p variation squares BG 1 1009355277. 1009355277. ** Block/.BG 4 1668538464. 417134616. ** Ca 1 2548192691. 2548192691. ** c 1 127270938. 127270938. * R 3 225588623. 75196208. * BG X Ca 1 197031762. 197031762. ** BG x C 1 431358. 431358. * BG x R 3 256132120. 85377373. ** Ca X C 1 34178007. 34178007. * Ca x R 3 354035497. . 118011832. * c X R 3 214532575. 71510858. * Higher interactions 13 445719027. 34286079. Residual-block 60 3521•718071. 58745301. Redisual-treel 95 2480675205. 26112371. Total 190 13086399616. 1 used as error term 2 ** = PO.Ol; * = PO.OS Arithmetic means for 1 ml and 2SOO ml Growth regulators ltsca levels 0 ppm BA GA Mean 2000 + 500 ppm 3 23 l1 Ci 10015 7442 8728 a 46 l1 Ci 19375 12729 16052 b mean 14695 a 10085 b 12390 Cultivars rootstocks Spartan H.R. Delicious Mean M26 12820 15221 14020 a M7 10339 12205 11272 ab MM106 12415 10661 11538 b MMlll 10714 14747 12730 b mean 11572 13209 12390 Growth regulators rootstocks 0 ppril BA GA Mean 2000 + 500 ppm M26 14794 13247 14020 a M7 12878 9666 11272 ab MM106 14820 8255 11538 b MMlll 16287 9173 12730 b mean 14695 10085 12390 5 ' Ca levels Cultivars 23 l1 Ci 46 l1 Ci Mean Spartan 8334 14810 11572 a H.R. Delicious 9122 17295 13209 b mean 8728 16052 12390 3 means followed by the same letter are not significantly different at P = 0.05 according to the Duncan's new multiple-range test. TABLE IA. AOV of the radiocalcium uptake by the whole tree CAU (log1)

Source of variation DF Sum of squares Mean square p BG 1 3.0832230 3.0832230 ** Block/BG 4 2.9018277 0.7254569 ** Ca 1 2.0929857 2.0929857 ** c 1 0.2698365 0.2698365 R 3 0.2946523 0.0982174 BG x Ca 1 0.2703684 0.2703684 BG x C 1 0.0000970 0.0000970 BG X R 3 0.7382884 0.2460961 * Ca X C 1 0.0638566 0.0638566 Ca X R 3 0.2773653 0.0924551 C X R 3 0.1542696 0.0514232 Higher interactions 10 1.4293012 0.1429301 Residual-block 60 7.7056093 0.1284268 Residua1-tree2 98 6.9166709 0.0705783 Total 190 26.1983518

1 using base 10 logarithmic transformation

2 used as error term

Geometric means in logarithmic and natural DPM numbers

Growth regulators

45 Ca levels 0 ppm BA GA 2000 + 500 ppm mean 3 23 JJCi 3.957(0955) 3. 778 (5992) 3.867(7366) a 46 pCi 4.242(17465) 3.912(8166) 4.077(11943)b mean 4.100(12575) 3.845(6995) 3.972(9379)

3means followed by the same letter are not significantly different at P = 0.05 according to the Duncan's new multiple-range test. TABLE II. AOV of the young shoots; radioca1cium uptake/mg dry weight ~ CA/D (log1 ) Source of variation DF Sum of squares Mean square p3 BG '1 0.53585851 0.53585051 * B1ock/BG 2 3.33691957 1.66845978 ** Ca 1 1.80463755 1.80463755 ** c 1 1.90621316 1.90621316 ** R 3 6.90801763 2.30267254 ** BG x Ca 1 o. 41406671 0.41406671 BG x C 1 0.09577476 0.09577476 BG x R 3 0.81180847 0.27060282 Ca XC 1 0.18995501 0.18995501 Ca X R 3 0.90380705 0.30126902 C X R 3 0.07672516 0.02557505 Higher interactionsl3 1.54791958 0.11907074 Residual-bloc~ 30 5.40893788 0.18029793 Residual-tree 64 . 7.32896741 0.11451512 Total 127 31.26960844

1using base 10 logarithmic transformation 2used as error term 3 ** • PO.Ol; * = P0.• 05 Geometric means in logarithmic and natural DPH numbers Growth regulators 45 Ca levels 0 ppm BA GA Mean % 2000+ 500 ppm 23lJCi 4.4119(25817) 4.3963(24906) 4.4041(25357) 36.7 a~ 46lJCi 4. 7632(57969) 4.5200(33113) 4.6416(43813) 63.4 b mean 4.5875(38681) 4.4581(28714) 4.5228(33327) (57. 4%) (42.6%) a b Cultivars rootstocks Spartan H.R. Delicious mean % M26 4.8917(77929)(1) 4.5991(39728) 4.7454(55641) 37.2 a M7 4.6816(48039) 4.5119(32501) 4.5967(39509) 26.3 a MM106 4.7319(53938) 4.5009(31688) 4.6164(41343) 27.3 a MMlll 4.2744(18810) 3.9913(9802) 4.1328(13577) 9 b mean 4.6449(44147) . 4.4008(25165) 4. 5228(33327) (63.7%) (36~3%) 4 a b mean separation at P = 0.05 (Duncan's) Q TABLE III. AOV of the old leaves; radiocalcium uptake/mg dry weight CA/D (log1 )

Source of variation DF . Sum of squares Mean square p3 BG '1 0.26226438 0.26226438 Block/BG 4 2.85569036 1.42784518 * Ca 1 5.89310945 5.89310945 ** c 1 1.23419727 1.23419727 * R 3 8.70879955 2.90293318 ** BG x Ca 1 0.01832329 0.01832329 BG X C 1 0.18297115 0.18297115 BG x R 3 0.78780544 0.26260181 Ca x C 1 0.06032907 0.06032907 Ca x R 3 3.84943674 1.28314558 * C X R 3 1.08478583 0.36159528 Higher interactions 13 3.01401696 0.23184746 Residual-block 60 11.51201010 0.38373367 Residual-tree2 96 20.70177867 0.32346529 Total 191 60.16551824 1 using base 10 logarithmic transformation zused as error term 3 ** • PO.Ol; * • P0.05 Geometric means in logarithmic and natural DPM numbers

Growth regulators 45 ca levels 0 ppm BA GA Mean % 2000 + 500 ppm 4 23 llCi 4.3432(22039) 4 .4577(28688) 4.4004(25142)27.1 a 46 pCi 4.7963(62560) 4.8629 (72928) 4.8296(67546)72.9 b mean 4.5697(37128) 4.6603(45740) 4.6150(41210) (44.8%) (55.2%) a a Cultivars rootstocks Spartan H.R. Delicious Mean % M26 4.9497(89063) 4.5573(36083) 4.7535(56689)29.7 a M7 4.7327(54038) 4.5987(39692} 4.6657(46313)24.4 a MM106 4.8235{66604) 4.8993(79304) 4.8614(72677)38.0 a MM111 4.3469{22228) 4.0120(10280) 4.1795(15118) 7.9 mean 4. 7132{51665) 4.5168(32870) 4.6150(41210) {61.1%) (38.9%) a b 4 mean separation at P • 0.05 (Duncan's) TABLE IV. AOV of the high bark; radiocalcium uptake/mg dry weight CA/D(log1)

Source of variation DF Sum of squares Mean Square p3 BG 1 0.18782396 0.18782396 Block/BG 2 1. 70202911 0.85101455 ** Ca 1 4.88365770 4.88365770 ** e 1 0.82332516 0.82332516 * R 3 5.14257834 1. 71419278 ** BG x ea 1 0.66487127 0.66487127 * BG X C 1 0.02334642 0.02334642 BG x R 3 0.29588659 0.09862886 ea x e 1 0.01112651 ,0.01112651 ea x R 3 0.70687722 0.23562574 e .X R 3 0.78470938 0.26156979 Higher interactions13 0.98722897 0.07594069 Residual-bloc~ 30 0.17520485 0.17520485 Residual-tree 64 9.88538381 0.15445912 Total 127 31.35498998 1 using base 10 logarithmic transformation 2used as error term 3 . ** • PO.Ol; * = ~0.05 Geometric means in logarithmic and natural DPM numbers Growth regulators 45 ea levels 0 ppm BA GA 2000 + 500 ppm Mean % 4 23 llei 4.5905(38949) 4.8113(64759) 4.7009(50222) 28.9 a 46 }lCi 5.1253(133443) 5.0578(11434) 5.0915(123452) 71.1 b mean 4.8579(72094) 4.9345(86000) 4.8962(78740) (45.6%) (54.4%) a a eultivars rootstocks Spartan H.R. Delicious Mean % M26 5.0250(105925) 4.9404(87176) 4.9827(96094) 27.8 ab M7 5.0591(114577) 4.7555(56951) 4.9073(80779) 23.3 b MM106 5.0848(122969) 5.1496(141123) 5 .1197 (131733) 38. a MM111 4.7317(53914) 4.4184(26206) 4.5751(37592) 10.9 mean 4.9764(94710) 4.8160(65463) 4.8962(78740) (59%) (41%) a b 4 Q mean separation at P = 0.05 (Duncan' s) TABLE V. OAV of the low bark; radiocalcium uptake/mg dry weight CA/D (log_)1

Source of variation DF Sum of squares Mean sqWtres p3

BG 1 0.28284705 0.28284705 Block/BG 2 2.44855881 1.22427940 ** Ca 1 5.22693539 5.22693539 ** c 1 0.20355106 0.20355106 R 3 0.23927227 0.07975742 BG x Ca 1 o. 79517877 0.79517877 BG x C 1 0.06912365 0.06912385 * BG x R 3 0.26204306 0.08734769 Ca X C 1 0.01246929 0.01246929 Ca x R 3 0.39782354 0.13260785 C X R 3 0.62160398 0.20720133 Higher interactions 13 1.00560836 0.07935449 Residual-block 30 3.82421648 0.12747388 Residual-tree2 64 9.18671339 0.14354240 Total 127 24.57594528

1 using base 10 logarithmic transformation 2used as error term 3 ** • P0.01; * • P0.05 Geometric means in logarithmic and natural DPM numbers Growth regulators

45 Ca levels 0 ppm BA GA mean 2000 + 500 ppm 4 23 llCi 5.4243(265642) 5.4879(307537) 5.4561(285822)28.3 a 46 JJCi 5.9861(968491) 5.7345(542622) 5.8603(724931)71.7 b mean 5.7052(507220) 5 .6112(408504) 5.6582(455194) (55.4%) (44.6%) a a Cultivars rootstocks Spartan H.R. Delicious mean M26 5. 7080(510501) 5.6568(453730) 5.6824(481279)26.3 a M7 5.6914(491358) 5.6110(408316) 5.6512(447916)24.5 a MM106 5.6566(453521) 5.7585(573451) 5.7075(509915)27.9 a MMlll 5.7364(545001) 5 .4471(279961) 5.5918(390658)21.3 a mean 5.6981(498995) 5.6183(415238) 5.6582(455194) (54.6%) (45.4%) a a

4 mean separation at P • 0.05 (Duncan's) TABLE VI. AOV of the root bark; radiocalcium uptake/mg dry weight 0 1 CA/D (log )

Source of variation DF Sum of squares Mean square p3

BG .1 0.030319009 0.030319009 Block/BG 2 0.443017974 0.221508987 * Ca 1 2.306199003 2.306199003 ** c 1 0.014095556 0.014095556 R 3 0.361132265 0.120377422 BG x Ca 1 0.022983398 0.022983398 BG x C 1 0.028148631 0.028148631 BG x R 3 0.182775469 0.060925156 ea x c 1 0.100153912 0.100153912 Ca x R 3 0.032729133 0.010909711 C x R 3 0.050637509 0.016879170 Higher interactions 13 0.899160829 0.069166218 Residual-block 30 2.046260982 0.068208699 Residual-tree2 64 3.892026754 0.060812918 Total 127 10.409640425 1 using base 10 logarithmic transformation 2used as error term 3 ** • PO.Ol; * • PO.OS Geometric means in logarithmic and natural numbers Growth regulators 45 Ca levels 0 ppm BA GA mean % 2000 + 500 ppm ' 4 23 llCi 5.8847{766827) 5.8271{671,578) 5.8559{717624) ~ 35 a 46 l1Ci 6.1264(1.337,820) 6.1244(1,325,556) 6.1224(1,331,670) 65 b mean 6.0056(1,012,970) 5.9748(943,620) 5.9748(977679) (51.8%) {48.2%) a a Cultivars rootstocks Spartan H.R. Delicious mean % M26 6.0249{1,059,000) 5.9757{945576) 6.0003(1,000,680) 25.4 a M7 5.9557{862,377) 5.8901(776420) 5.9129{818271) 20.8 a MM106 6.0035(1,008,090) 5.9669(926609) 5 .9852(966491) 24.5 a MMlll 6.0385(1,092,690) 6.0860(1,218,980) 6.0622(1,153,980) 29.3 a mean 6.0007(1,001,610) 5.9797(954324) 5.~902{977679) (51. 2%) (48.8%) a a

4 mean separation of P = 0,05 (Duncan's) TABLE VII. Distribution of radiocalcium throughout the tree (geometric

means/mg dry weight) tree part DPM % mean young shoots 33,327 2.10 a 1 old leaves 41,210 2.60 b high bark 78,740 4.96 c low bark 455,194 28.70 d root bark 977,679 61.64 c

Total: 1,585,150 100.00

1Mean separation at P • .OS according to the Duncan's new multiple-range test. Q TABLE VIII. Distribution of radiocalcium at two concentration levels throughout the tree (geometric means/mg dry weight)

45 Tissue . Ca level DPM % LSD p =.01 p = .os Young shoots 23 lJCi 25,357 36.7 2318 1742 46 llCi 43,813 63.3 3800 2857 total 69,170 100

old leaves 23 }..ICi 25,142 27.1 3866 2906 46 }..ICi 67,546 72.9 9462 7113

total 92,688 100

high bark 23 JJCi 50,222 29 4995 3755 46 }..ICi 122,452 71 11336 8523

total 173,674 100

low bark 23 J.!Ci 285,822 28.3 21981 17748 46 lJCi 724,931 71.7 55753 41910 total 1,010,753 100

root bark 23 }..ICi 717,624 35 35828 27022 46 JJCi 1,331,670 65 63788 47945 total 2,049,294 100 x z • 31.2 (23 JJCi) x z = 68.8 (46 JJCi) 45 (J TABLE IX. Distribution of calcium within each tissue and within each rootstock (geometric means/mg dry weight)

Tissue rootstock DPM % % LSD within each within each P=.Ol P=.05 tissue rootstock

young shoots M26 55,641 37.07 3.29 4720 3548 M7 39,509 26.33 2.76 3460 2607

MM106 41,343 27.55 2.40 3605 2710

MMlll 13,577 9.05 0.84 1322 994 total 150,070

old leaves· M26 56,689 29.71 3.35 8220 6065

M7 46,313 24.27 3.23 6715 5048

MM106 72,677 38.09 4.22 10115 7603

MMlll 15,118 7.93 0.94 2447 1840 total 190,797

high bark M26 96,094 27.76 5.68 9016 6779

M7 80,779 23.34 5.69 7696 5786

MM106 313,733 38.05 7.65 12030 9044

MMlll 37,592 10.85 2.33 3841 2888 total 346,198

low bark M26 481,279 26.30 28.47 38173 28695

M7 447,916 24.48 31.26 35723 26853

MM106 509,915 27.87 29.61 40266 30269

MM111 390,658 21.35 24.25 31487 23669 total 1,829,768

root bark M26 1,000,680 25.40 59.21 48924 36773

M7 818,271 20.78 57.11 40487 30432

MM106 966,491 24.53 56.12 47372 35606

C£:01.~ I"* 1'\c,.. 11 MMlll 1,153,980 24.39 71 "'· TABLE X. Distribution of radiocalcium within each cultivar and each tissue (geometric means/mg dry weight)

Tissue Cultivar DPM % % LSD LSD (pooled) within each of all P•.Ol P•.OS P•.Ol P•.OS tissue tissue young shoots Spartan 44,174 63.7 3.0 3826 2876 6128 4606 H.R.Delicious:25,.165 36.3 1.9 2302 1730

old leaves Spartan 51,665 61.1 3.5 7416 5515 12339 9296 H.R.Delicious 32,870 38.9 2.5 4923 3701

high bark Spartan 94,710 59.1 6.5 8897 6689 15252 11467 H. R. Delicious 65,463 40.9 5.0 6355 4778

low bark Spartan 268,904 54.5 18.4 39468 29238 72778 54278 H.R.Delicious 224,749 45.5 17.3 33310 25040

root bark Spartan 1,001,610 51.2 68.6 48966 36804 95784 71994 H.R.Delicious 954,324 48.8 73.3 46818 35190 2 TABLE XI. AOV of the young shoots; radio~alcium uptake/~m of tissue eA/R (1og1)

Source of variation DF Sum of squares Mean square p3 BG 1 2.48775117 2.48775117 ** Block/BG 4 2.20315768 0.55078942 * ea. 1 3.25350301 3.25350301 ** e 1 3.17370049 3.17370049 ** ·R 3 10.62901972 3.54300657 ** BG x ea 1 0.63689192 0.63689192 BG X e 1 0.50386914 0.50386914 BG x R 3 1.70352193 0.56784064 ea X e 1 0.23227634 0.23227634 Ca x R 3 0.47862454 0.15954151 eX R 3 0.72602250 0.24200750 Higher interactions 13 2.80075428 0.21544260 Residual-block 60 25.25771289 0.42096188 Residual-tree2 96 20.46201227 0.21314596 Total 191 74.54881787

1 using base 10 logarithmic transformation 2 used as error term 3 •• K PO.Ol; * = PO.OS Geometric means in logarithmic and natural DPM numbers Growth regulatdrs 45 ea levels 0 ppm BA GA 200 + 500 ppm mean 23 11ei 2. 5183(330) 2.8612(726) 2.6898(490) 46 lJCi 2.89387(783) 3.0063(1015) 2.9501(891) mean 2.70610(508) 2.9338(859) 2.8199(661) eultivars rootstock Spartan H.R. Delicious mean M26 2.9608(914) 2.6770(475) 2.8189(659) M7 3.1613(1450) 2.9012(796) 3.0312(1075) MM106 3.0280(1066) 2.9579(908) 2.9929(984) MM111 2.6440(441) 2.2294(170) 2.4367(273) mean 2.9485(888) 2.6914(491) 2.8199(661) 2 TABLE XII. AOV of the old leaves; radiocalcium uptake/cm of tissue CA/R (log1 )

Source of variation DF Sum of squares Mean square

BG 1 0.32729106 0.32729106 Block/BG 4 5.48917624 1.37229406 ** ea 1 3.95592063 3.95592063 ** c 1 5.64083999 5.64083999 ** R 3 16.36256485 5.45418828 ** BG X Ca 1 0.11903883 0.11903883 BG x C 1 0.01696587 0.01696587 BG x R 3 1.16387708 0.38795903 Ca XC 1 0.00000473 0.00000473 Ca x,·,R 3 2.96059752 0.98686584 ** c X R 3 1. 71210212 0.57070071 Higher interactions 13 1.69989978 0.13076152 Residual-block 60 16.62546057 0.27709101 Residual-tree2 96 17.57897981 0.18311437 Total 191 73.65271909

1using logarithmic transformation 2used as error term 3 ** • PO.Ol; * • P0.05 Geometric means in logarithmic and natural DPM numbers Growth regulators

45 ca levels 0 ppm BA GA mean 200 + 500 ppm

23 ).lCi 2.1191(132) 2.2514(178) 2.1853(154) 46 ).lCi 2.4559(286) 2.4887(308) 2.4723(297) mean 2.2875(194) 2.3700(234) 2.3288(213) Cu1tivars rootstocks Spartan H.R. Delicious mean M26 2.5516(356) 2.2110(163) 2.3813(241) M7 2.6344(431) 2.4238(26.5) 2.5291(338) MM106 2. 6516 (448) 2.4826(304) 2.5670(369) MMlll 2.1631(146) 1.5121( 33) 1.8376( 69) mean 2.5002(316) 2.1574(144) 2.3288{213) 2 TABLE XIII. AOV of the high bark; radioca1cium uptake/cm of tissue CA/R (1og1)

Source of variation DF Sum of squares Mean squares

BG 1 0.50405282 0.50405282 Block/BG 4 1.80412278 0.45103070 * Ca 1 4.11795783 4.11795783 •• c 1 1.53651011 1.53651011 ** R 3 5.871790084 1.95730028 ** BG x Ca 1 0.65879226 0.65879226 · BG XC 1 0.04403424 0.04403424 * BG X R 3 0.35905136 0.11968379 Ca x C 1 0.01175201 0.01175201 Ca x R 3 1.15557511 0.38519170 C X R 3 0 •. 39319528 0.13106509 Higher interactions 13 0.96207351 0.07400565 Residual-block 60 9.9432176 0.1657.3203 Residua1•tree2 96 13.8965596 0.14475579 Total 191 41.25949588 1 . using base 10 logarithmic transformation 2used as error term 3 ** • P0.01; * • P0.05 Geometric means ip logarithmic and natural DPM numbers Growth regulators 45 Ca levels 0 ppm BA GA mean 200 + 500 ppm 23 pCi 3.0337(1081) 3.2534(1792) 3.1435 (1392) 46 pCi 3.4438(2778) 3.4291(2686) 3.4364(2732) mean 3.2388(1733) 3.3412 (2194) 3.2900(1950) Cultivars

rootstocks Spartan H.R. Delicious mean

M26 3.4133(2590) 3.2256(1681) 3.3194(2086) M7 3.4397(2752) 3.3088(2036) 3.3742(2367) MM106 3.5039(3191) 3.4270(2673) 3.4654(2920) MMlll 3.1610(1449) 2.8408(693) 3.0009(1002) mean 3.3795(2396) 3.2005(1587) 3.2900(1950) 2 TABLE XIV. AOV of the low bark; radiocalcium uptake/cm of tissue CA/R (log1)

Source of variation DF Sum of squares Mean squar-e

BG 1 0.0000053 0.0000053 Block/BG 4 3.3884231 0.8471058 ** Ca 1 3.7198355 3.7198355 ** c 1 0.5665761. 0.5665761 ** R 3 1.5355296 0.5118432 ** BG x Ca 1 0.0980623 0.0980623 BG x C 1 0.0056872 0.0056872 BG x R 3 0.1062398 0.0354133 Ca x C 1 0.0171324 0.0171324 Ca x R 3 0.3125200 0.1041733 C X R 3 0.0707283 0.0235761 Higher interactions 13 0.7270242 0.0559249 Residual-block 60 2.5230313 0.0420505 Residua1-tree2 96 4.4001096 0.0468097 · Total 191 17.4709048

1using base 10 logarithmic transformation 2 used as error term 3 ** • PO.Ol; * = PO.OS

Geometric means in logarithmic and n~tural DPM numbers

Growth regulators

45 Ca levels 0 ppm BA GA mean ' 2000 + 500 ppm

23 J.!Ci 3.8720(7447) 3.9174(8268) 3.8947(7847) 46 uci 4.1990 ( 15812) 4.1530(14223) 4.1760(14997) mean 4.0355(10852) 4.0352(10844) 4.0353(10847)

Cu1tivars

rootstock Spartan H.R. Delicious mean

M26 4.1280(13428) 4.0290(10691) 4.0785(11981) M7 4.1445(13948) 4. 0719 (11800) 4.1082 (12829) MM106 4.1197(13173) 4.0267(10634) 4.0732(11836) MM111 3.9687(9305) 3.7943(6227) 3.8815(7612) mean 4.0902(12308) 3.9805(9561) 4. 0353 (1084 7) c TABLE XV. AOV of the root bark; radiocalcium uptake/cm2 of tissue

CA/R (lol)

Source of variation DF Sum of squares Mean square

BG 1 0.023844196 0.023844196 Block/BG 4 0.570674314 0.142668579 ** Ca 1 4.185555896 4.185555896 ** c 1 0.144225141 0.144225141 ** R 3 0.607387269 0.202462423 ** BG x Ca 1 0.006823646 0.006823646 BG x C 1 0.000046523 0.000046523 BG x R 3 0.115149578 0.038383193 * Ca X C 1 0.010021725 0.010021725 Ca x R 3 0.065516746 0.021838915 C X R 3 0.012846443 0.004282148 Higher interactions 13 0.101478814 0.007806063 Residual-block 60 0.584783895 0.009746398 Redisual-tree2 96 1.170301082 0.012190636 Total .• 191 7.598655268 1 . using base 10 logarithmic transformation 2used as error term 3 ** • P0.01; * = PO.OS

Geometric means in logarithmic and natural DPM numbers

Growth regula tors . 45 Ca levels 0 ppm BA GA mean 2000 + 500 ppm 23 llCi 4.3152(20663) 4.3494(22356) 4.3323(21493) 46 llCi 4.6224(41918) 4.6328(42934) 4.6276(42423) mean 4.4688(29431) 4.4911(30981) 4.4800(30199) · Cu1tivars

rootstock Spartan H.R. Delicious mean

M26 4.5792(37949) 4.5217(33243) 4.5404(35514) M7 4. 4936 (31160) 4. 4489 ( 28112) 4.4713(29600) MM106 4.5210(33189) 4.4841(30486) 4.5026(31813) MMlll 4.4357(27271) 4.3556(22678) 4.3957(24871) mean 4.5074(32166) 4.4526(28353) 4.4800(30199) ~ Table XVI. Confidence intervals

YOUNG SHOOTS

p- .os p.: .01 Log. Arith. Log. Aritb.

M26 4.8650 73282 4.9045 80260

·. 4.7454 55641.4 4.7454 55641.4 4.6258 42247 4.5863 38574

M7 4.7163 52035 4.7558 56990

4.5967 39509.1 4.5967 39509.1 4.4771 29998 4.4376 27390

MM106 4.7360 54450 4.7755 59634 4.6164 41342.6 4.6164 41342.6 4.4968 31390 4.4573 28661

MM111 4.2524 17881 4.2919 19583 4.1328 13576.8 4.1328 13576.8 4.0132 10308 3.9737 9412 Table XVII. Confidence intervals

OLD LEAVES

p = .os p = .01 Log. Arith. Log. Arith.

M26 4.9546 90074 5.0209 104930 4.7535 56688.9 4.7535 56688.9 4.5524 35677 4.4861 30626

M7 4.8668 73586 4.9331 85723

4 •. 6657 46312.5 4.6657 46312.5 4.4646 29147 4.3983 25020

MM106 5.0625 115478 5.1288 134524

4.8614 72677.0 4.8614 72677.0 4.6603 45740 4.5940 39264

MM111 4.3806 24021 4.4469 27983 4.1795 15118.1 4.1795 15118.1 3.9784 9514 3.9121 8167 Table XVIII. Confidence intervals

HIGH BARK

p a .os p = .01 Log. Arith.· Log. Arith.

M26 5.1216 132312 5.1675 147061

4.9827 96094.0 4.9827 96094.0

4.8438 69791 4.7979 62791

M7 5.0462 111224 5.0921 123623

4.9073 80778.8 4.9073 80778.8 4.7684 58667 4.7225 52783

MM106 5.2586 181383 5.3045 201604

5.1197 131733.0 5.1197 131733.0

4.9808 95675 4.9349 86079

MMlll 4.7140 51760 4.7599 . 57530 4.5751 37592.2 4.5751 37592.2

4.4362 27302 4.3903 24564 0

Table XIX. Confidence intervals

LOW BARK

p = .os p = .01 Log. Arith. Log. Arith.

M26 5.8163 655088 5.8605 725270

5.6824 481279.0 5.6824 481279.0

5.5485 353590 5.5043 319374

M7 5. 7851 609677 5.8293 674994

5.6512 447916.0 5.6512 447916.0 5.5173 329078 5.4731 297235

MM106 5.8414 694064 5.8856 768422

5.7075 . 509915.0 5.7075 509915.0

5.5736 374627 5.5294 338376

MM111 5.7257 531740 5.7699 588708

5.5918 390658.0 5.5918 390658.0 5.4579 287011 5.4137 259238 M7 6.0001 1000230 6.0288 1068562

5.9129 818271.0 5.9129 818271.0 ' 5.8257 669422 5.7970 626613

MM106 6.0724 1181408 6.1011 1262118

5.9852 966491.0 5.9852 966491.0

5.8980 790678 5.8693 740116

MM111 6.1494 1410587 6.1781 1506954 6.0622 1153980.0 6.0622 1153980.0 5.9750 944060 5.9463 883690 Table XXI. Confidence intervals

WOLE TREE p = .os p ... .01 Log. Arith. Log. Arith.

Young 4.5879 38716 4.6094 40681 Shoots 4.5228 33327 4.5228 33327

4.4577 28687 4.4362 27302

Old 4.7244 53015 4.7606 57623 Leaves 4.6150 41209 4.6150 41209

4.5056 32033 4.4694 29471

High 4.9718 93713 4.9968 99265 Bark 4.8962 78740 4.8962 78740

4.8206 66160 4.7956 62459

Low 5.7311 538393 5.7551 568983 Bark 5.6582 455194 5.6582 455194 5.5853 384857 5.5613 364166

Root 6.0376 1090435 6.0533 1130576 Bark 5.9902 977679 5.9902 977679

5.9428 876597 5.9271 845473