Rootstocks and Mineral Nutrition of Citrus

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Rootstocksand Mineral Nutrition of Citrus

H. K. Wutscher

Introduction

Mineral nutrition of plants is a topic which has beendi~ussed s'ince the beginningof agriculture. Aristotte wrote treatises on it, and until the 15th and 16th century the consensuswas that whateverplants needto grow, it al camefrom the soil. Al- though Nicholasde Cusaand Van Helmont, after his famousexperiment with a willow cutting, had ideasthat the sourceof the materialsthat makeup a plant was not quite assimple, it wasthe work of Priesdy,Ingenhousz, and De Sausa.re,and the discoveryof photosynthesisin the 18th and early 19th century that put mineral nutrition in its proper persp..:tiveas only one facet in the metabolismof plants. The grandold men of plant physiology,Sachs and Pfeffer, worked out the basisof mineral nutrition aswe know it today in the secondhalf of the last century and gaveus an understandingof the constituentsof plant tissuesand the essentialityof someelements. In a more practi:al vein, their contemporaries,Boussingault, Liebig, Gilbert, and Lawes,showed the possibility of increagngcrop yields by applicationof mineral fertilizers. Furtherwork, mostly with solution culture, showedthe essentialityof a seriesof elementswhich plants needin only very small anounts, the so-calledmicro-elements. A greatamount of effort went into trying to find the combination of variouselements for optinum plant growth and resultedin many publicationsof little practicalvalue for 2 reasons.First, becausemuch of the wort

Mineral nutrition studiesof citrus and other tree crops havealmost becomesynonymous with leaf analysis. Following the developmentof instrumentspermitting the rapid analysisof largenumbers of samplesand the pioneeringwork of Lundegardh, a large body of knowledgehas beenbuilt up empirically correlatingthe levelsof nutrient elementsin the leavesto tree perform- ance,providing a more sensitiveand lessambiguous method than deficiency or toxicity symptomsto diagnosethe nutrient sta- tus of trees. The rangesgiven in tablesof nutrient standardsare usuallyfairly wide (2). Nevertheless,leaf levelslisted as "opti- mum" often cannot be maintainedbecause of local peculiarities,like irrigation water high in salt and variationsin soil and climate. It is easyto overestimatethe effect of mineral nutrition; miraclesare often expectedfrom fertiizer application. But the plant doesn'tnecessarily take up everythingthat's applied andas Smith (31) hasshown in a nitrogenfertilization trial, the difference in yield betweentrees starved for N and thosereceiving high levelsis often no more than 200/0.

Rootstock Eff~ts

Becausethe root systemis the part of the plant which absorbsmineral elements(with the exceptionof nutrients appliedas foliar sprays)it is only logical that rootstocksshould havesome influence on the compositionof the scion. Substituting a gen- etically more or le$ distinct root systemis boundto havean effect on the scion and many reports bearthis out (seeLiterature Cited); however,the influence is by no meansonesided. The scion also influencesthe sizeand composition of the root system (17). Basicallythe scion and the rootstock, becauseof their different geneticmake-ups, remain separate entities, but one can influencethe behaviorof the other within certain narrow limits. The bud union is not a major factor in nutrient differences(36). Hodgson(18, 19) and Shannonand Zaphrir (28) investigatedthese relationships using reciprocally grafted rough lemon and trifoliate orangeplants, and plantswith 2 root systemsof the sameor both species.The scionsseemed to havea greaterinfluence on determiningplant sizethan the rootstock. Two root systemsgave no advantagein mineral uptake over one, but the rootstock specieshad distinct but different effects on the levelsof K, Ca and Fe in the leaves.Trifoliate orangeleaves were hi~er in K and lower in Cathan rough lemon leaves,regardless of rootstock,which seemsto indicate that the scion influencewas dominant in this case. Whenused as rootstock for rough lemon,trifoliate orangeimposed the pattern of lower Caand higher K on the scion. Rootstockand scion seemedto be equally effective in influencingthe Fe concentrationin the leaves,but the Fe concentrations reportedare excessivelyhigh, which castssome doubt on the m:curacyof the analyses.Two componentsdetermine the amount of an elementin the leaf; uptake by the roots and trandocation. The root only passeson materialsto the scion after its own re- quirementsare met. Analysesof plantswith deficiencies,particularly micro-elementdeficiencies, often show that while the above- groundparts arelow in someelement the roots still contain adequateor evensurprisingly high levelsof it. The trunk, of course, -98- is the site of ttanslocationand the effect of insertingan interstock of sufficient length should givesome indication on the relativeimportance of root uptake and translocation. Effectsof interstockson leaf composition of deciduousfruit trees havebeen reported (35,39). Table 1 shlPNsr~ative effectsof rootstocksand 45-cm long interstockson the leaf lev~s of 7 elementsin young grapefruittrees. The treeshad beengrown in containersfor 2 yearsbefore being planted in the field. Leaf Sllnpleswere taken from 4 two-tree plots of eachrootstock/interstock treatment 2 yearsafter planting. Analysisfor 12 ~ementsshowed no significantdifferences in P, Fe, In, Cu and Na with rootstock or interstock. In only a few instances wasit possibleto overridethe root influencewith an interstock. Treeswith Citrus macrophyllaroots and sour orangeand 'Cleopatra'mandarin interstocks had lower N levelsthan treeson C. macrophyJ/awithout an interstock. They bm aved much like treeson sour orangeand 'Cleopatra'roots. Treeswith EremocitrusgJauca hybrid interstocksand C. macrophylla roots accumulatedmore chloridesthan treesdirectly on C. macrophylla. Interstocks,with C. macrol!hylla as the common rootstock, affectedthe N concentrationin the leaves.With trifoliate interstock it washigher than with sour orange,'Cleo- patra', E~mocitrus glaucahybrid, and satsumainterstock. E. glaucahybrid interstock resultedin higher K lev~s than 'Changsha'mandarin interstock. Mn washigher with 'Savage'citrange and 'Changsha'mandarin than with E. glauca hybrid interstocks. Chlorideswere lower with sour orangeand 'Cleopatra'interstocks than with E. glaucahybrid interstock and lower with sour orangethan with 'Troyer' citrange. 'Cleopatra'mandarin interstock lowered B comparedto 'O.ri' Sat- sumointerstock. This is contrary to its behavioras a rootstock, where 'Cleopatra'is chloride-tolerantand B-sensitive(5). In spite of theseeffects of interstocks,root uptake and not tran~ocation appearsto be the dominant factor in determining leaf nutrient lev~s. There are severalreasons why eff~ts of rootstockson miner~ nutrition are important. They haveto be taken into ~. count when interpretingleaf analysisdata. Without a knowledgeof the nutritional idiosyncrasiesof a particular rootstock it is easyto misiudgethe nutritional statusof trees. The excessiveuptake of one elementcan set in motion one or more nutritional imbalancereactions, such as depressionof N by excessiveamounts of Ca (38). ExcessK depressesMg. High levelsof heavymetals can induce Fe deficiencysymptoms. At leastpart of the mechanismof rootstock influenceson fruit quality (30) is probably nutritional. If the rootstock is one of the sp~ies in the subtribal group Citrus there is some,but not too much, variation in leaf nutrient levelsbetween rootstocks, but \IIA1engratt-eompatible citrus relativesare used greater differencescan be expected. The ealtier mentionedinterstock datashowed that the interstockcausing most differencesin nutrient levels w. an E. glaucahybrid. The data in Table 2 showthatSeverinia can cause a rangeof unusualleaf nutrient patterns,among which accumulationof very high Mn levelsis the most striking feature.

Chlorosisremains as a little understoodmineral nutrition pro~em, althou~ Smith et al. (33) haveshown that levelsof Fe areconsistently lower in chlorotic than greenleaves. But often only part of the leavesof a tree arechlorotic, or they are chlorotic only at certain times of the year. In Texaswe haveobselVed that asthe treesget older th~ seemto be lesschlorosis- prone. Nevertheless,rootstocks clearly influencethe tendencyof treesto showchlorosis, and this is often strikingly demon- stratedin grovescontaining trees on more than one rootstock. In the rootstock trial describedin Table2 the sanplescontained both greenand chlorotic leavesand the correlation Fe content-chlorosisis not very good. The hi~ chlorosisresistance of 'Cleopatra'mandarin rootstock is noteworthy becausethis rootstock is often thou~t of aschlorosis-prone.With the advent of Fechelates, chlorosis is no longer the seriousproblem it oncewas, but chelatesare expensiveand if other considerations permit, the selectionof a chlorosis.resistantrootstock may be the most reasonablesolution to the problem.

s~t T 01erance One of the critical aspectsof differencesin mineraluptake with rootstocksis salt tolerance. Citrus is often grown in arid areaswhere the irrigation water containshigh levelsof salts. Strictly spe*ing "s~t tperar.:e" refersto only sulfatesand dtlorides, but B toleranceis often included. Most citrus speciesaccumulate B, and toxicity can be expectedwhen water containing 0.5 to 1.0 ppm B is used. Sulfatesand chlorides aff~t plant growth in 2 ways: 1) by increasingthe osmotic pressure of the soil solution, an effect sometimescalled "physiological drouth" and by 2) specificion eff~ts of the S04 = and the Cl- ions. B exertsonly a specificion effect becauseof its relativ~y low concentrationin the soil. Which of the 2 effects of sulfates and chlorides5 more important for citrus is a matter of contention, but at high concentrationsthe osmoticpressure is the dominant one. Citrus is r~atively tolerant of sulfate and fairly high concentrationsin irrigation water (3, 11) or culture solution (25) havelittle effect. As in many other aspectsof citriculture, Swin~e, the grandold man of citrus researeh,knew a great dealabout B toleranceand he suggested,on the basisof seedlingbehavior in greenhouse experiments, that S. buxifolia, E. glauca and -99-

Ata/antis disticha be used as rootstocks in areaswhere B was a problem (34).

Eaton and Blair (10) took his adviceand showedwith reciprocallygrafted trees of S. buxifolia and lemon in a sandculture experiment,that leaf B of 'Eureka' on Se~rinia was283 ppm, comparedto 1065 ppm on its own roots when 4 ppm B solution MS applied. Leavesof Se~rinia scionsgrafted on 'Eureka' lemon contained877 ppm B, while Se~rinia cuttings containedonly 390 ppm B evenwhen irrigatedwith 6 ppm B water. This showsclearly the ability of Sewrinia to excludeB. Roy (27), looking for rootstocksto alleviateB defK:ier.:y,found that leavesof orangetrees on trif~iate orangeand Cubanshaddock rootstock con. tained 70 and 74 ppm B while treeson sour orangecontained 14 to 23 ppm. Roughlemon, sweetorange, and 'Cleopatra'mandarin rootstock alsoinduced hi!IJ B levels. Haas(14) in California obtainedvery sin ilar results,with trif~iate orange,lemon shaddock, roughlemon, 'Savage'citrange, and 'Cleopatra'mandarin rootstocks accumulating high levelsof B comparedto severalstrains of sour orange. The B content of flowers, bark, and peel was alsoaffected. .

Later work by Smithet al. (32) in Florida, Cooperet al. (5) in Texas,and Embletonet al. (11) in California,produced similar results. A wide rangeof rootstockswas tested and the sweetlimes were foond to be B accumulators,while C.macrophylla was effective in keepingleaf Blow.

In a seriesof p.ers in the 1950'sand early 1960's,Cooper and his co-workers(3,4,6,7,9,22) reported on the chloride uptake of a wide rangeof rootstocks. The resultswere obtainedfrom plots wateredwith either salinewell water or salinizedriver water by methodssimilar to those developedby the U.s. Salinity Laboratory in Riverside,California (Richards[ed.] Agri. Hand. book No. 60,1954). 'Cleopatra',some other mandarins,and 'Rangpur' lime were effectivein keepingleaf chlorideslow, VIA1~e trifoliate orangeand most trifoliate hybrids accumulatedlarge amounts. Treeson C. macrophylla accumulatedfailty high chloride levelsbut rarely showedtoXK:ity symptoms.

In connectionwith chloride M:cumulationit wasshown (23,24) that trifoliate hybrid rootstocksknown to be cold hardy in other areas,were cold tender in Texasbecause of their tendencyto accumulatechlorides and B. In recentwork (41) we ifWesti- gatedthe effect of water .plication method on chloride and B uptake of young grapefruittrees grafted to 15 rootstocks,mostly 'Sunki' x trifoliate, 'Sunki' x C. macrophylla,and sour orangex 'Cleopatra'mandarin hybrids, togetherwith somevarieties of known salt tolerance,'Rangpur' and 'Cleopatra'. Watercontaining 3000 ppm total salts (1700 ppm C1") and 6 ppm B was applied separatelyto 3 setsof trees by flood irrigation, trickle irrigation and by subirrigationin sandculture. Treeson 5 of the 15 root- stockstook up equal amountsof chlorideswith all 3 irrigation methods. On another5 rootstocksthe chloride levelswere higher with flood irrigation than in sandculturewith trickle irrigation intermediate. The remainderreM:ted in variousways.

In the B treatmentsonly one rootstock did not respondto the method of irrigation. Nine rootstocksaccumulated equal a- mounts of B with flood and trickle irrigation andless with subirrigationin sandculture. Four other rootstocksreacted variously, wf1ileC. macrophylla,known to be B-tolerant,accumulated 1134 ppm B with trickle irrigation, 718 with flood irrigation and 332 in sandculture.

The resultsof experiments,where water containing3000 ppm or more total s~ts and6 ppm B was applied,are difficult to interpret when recommendingrootstocks for commercialuse. The singlemost important characteristicof a rootstock is that treeson it producelarge quantitiesof acceptablequality fruit. Often rootst(x;ksperforming well under the severeconditions of plot tests do not perform in the orchardas far asproduction is concerned.So the questionis at what level of salt accumulation mould a rootstock be eliminated. This meansfield testsunder ordinary orchardconditions are stil necessaryto determinesuit- abiity.

The data in Table 4 from a recent grapefruit rootstock trial (42) show that the differences in tendency to take up chlorides and B between rootstock can be detected even \-A1enirrigated with water of acceptable quality, in this case about 1000 ppm to. tal salts and 020 to 0.40 ppm B. 'Morton' citrange in this case accumulated twice IE much chi oride as sour orange, but the level WiE still in the acceptable range. Trees on 'Morton', however, yielded 30% more fruit over a 7-year period. Had these 2 rootstocks been compared in a plot test strictly on the basis of chloride uptake 'Morton' certainly would have been eliminated as un. suita~e. It seemsin selecting a rootstock we have to be somewhat tolerant of weaknessesand keep the overall picture in mind. -100-

Effects of Rootstock on Individual Elements

Becauseof the wide rangeof conditions underwhich the testswere carried out it is impossibleto put absolutevalues on the levelsof a givenelement reported in the literature with a certain rootstock andclassify them as'l1igh" or '11M". Most reports,however, are basedon comparisonswithin arraysof rootstockscontaining widely usedrootstocks like rough lemon,sour orange,or trifoliate orangeand statements on the relativeamount of accumulationof elementscan be made. The following is a compilation of such reports. -101.

BORON

Rootstocks Reference& Scion

High 8 LowS Eaton and Blair (10) Lemon S.buxifo/ia Scion: S. buxifolia Lemon

Rough lemon Sour orange Roy (27) Scion: 'ParsonBrown' orange 'Cleo~atra' mandarin 'Valencia' orange Haas(14) Trifoliate orange Sour orange 'lemon' Shaddock Grapefruit Scion: 'Valencia' orange Smith et al. (32) 'Rusk' citrange Sour orange Scion: 'Valencia' orange Grapefruit

'Cleopatra'mandarin Sour orange Cooperet al. (5) Scion: 'Valencia' orange Grapefruit

'King' mandarin Rough lemon Cooper et a/. (8) Scion: Grapefruit 'Sampson'tangelo S.buxifolia

'Cleopatra'mandarin Sour orange Cooperet al. (7) Scion: Grapefruit

'Cleopatra'mandarin C. macrophyl/a Cooperand Peynado(6) 'Ponkan' mandarin Citrusmoi Scion: Grapefruit

Citrumelo C.P.B.4475 C. macrophylla Peynado and Young (22) 'Ponkan' mandarin Citrus moi Scion: Grapefruit

C. macrophy/la Embleton et al. (11) Grapefruit Scion: Lemon 'Vuzu'

C59-24 (Rangpur x Trifoliate) S. buxifolia Wutscheret al. (40) 'Milam' rough lemon C55-24-4 ('Cleopatra' x Trifoliate) Scion: Grapefruit Sharplesand Hilgeman(29) Roughlemon Sour orange Scion: Various

Wutscherand Shull (42) 'Ponkan' mandarin Sour orange Scion: Grapefruit 'Morton' citrange 'Abers' sour orange -102.

CHLORIDE

Rootstocks Reference& Scion Highcr Lowcr

Sour orange 'Cleopatra'mandarin Cooperet a/ (4) Scion: 'Valencia' orange Grape'ruit

'Etrog' citron 'Rangpur'lime Cooperand Gorton (5) 'Rusk' citrange S. buxifo/ia Scion: Grapefruit

'Thomasville'citrangequat 'Sampson'tangelo Cooperand Shull (9) Citrangor 'Cleopatra'mandarin Scion: Grapefruit

Sour orange 'Cleopatra'mandarin Cooperet al. (7) Scion: Grapefruit

'Carrizo' citrange 'T aiwanica'orange Cooperand Peynado(6) 'Colombian'sweet lime 'Cleopatra'mandarin Scion: Grapefruit

'Troyer'citrange 'Timkat' mandarin Cooper(3) 'Carrizo' citrange 'Cleopatra'mandarin Scion: Grapefruit

Citrusmoi 'Sunki' mandarin Peynadoand Young (22) 'Carrizo' citrange 'Tim kat' mandarin Scion: Grapefruit

'Troyer' citrange 'Cleopatra'mandarin Wutscher et al. (40) Sour orange Scion: Grapefruit

'Carrizo' citrange 'Tim kat' mandarin Wutscherand Shull (42) 'Troyer' citrange 'Bittemveet' sour orange Scion: Grapefruit

SULFUR

Rootstocks Reference& Scion

HighS LowS

Roughlemon 'Cleopatra'mandarin Haas(15) Grapefruit Trifoliate orange Scion: 'Valencia' orange

Grapefruit 'Cleopatra'mandarin Rasmussenand Smith (25) Sour orange Roughlemon Scion: 'Valencia' orange 'ParsonBrown' orange

'Cleopatra'mandarin Sour orange Cooper(J) Scion: Grapefruit -103.

SODIUM

Rootstocks Reference& Scion

High Na Low Na

'Brownell' citradia Sour orange Cooper and Shull (9) 'Saunders'citrange Roughlemon Scion: Grapefruit

'Sampson'tangelo 'Cleopatra'mandarin Joneset at. (20) 'Rangpur' lime Scion: lemon

'Cleopatra'mandarin Sour orange Cooperet al. (7) Scion: Grapefruit

'Kara' mandarin Sour orange Cooper(3) 'Sanguinea'mandarin 'Gzel'sweet orange Scion: Grapefruit

Citrumelo C.P.B.4475 Sour orange Peynadoand Young (22) 'Ponkan' mandarin C. macrophylla Scion: Grapefruit

'Yuzu' Sweet orange Embletonetal. (11) Citrusmoi Scion: Lemon

Roughlemon Sour orange Sharplesand Hilgeman(29) Scion: 'Valencia' orange

'Timkat' mandarin 'Bittersweet'sour orange Wutscherand Shull (42) 'Ponkan' mandarin 'Morton' citrange Scion: Grapefruit

COPPER

Rootstocks Reference& Scion

High Cu Low Cu

'Rusk' citrange Sour orange Smith et al. (32) Sweet orange Rough lemon Scion: 'Valencia' orange s. buxifolia C61-251(Shekwasha x 'Koethen') Wutscher et al. (40) 'Troyer' citrange C55-24-4('Cleopatra' x Trifoliate) Scion: Grapefruit 104-

MAGNESIUM Rootstocks Reference& Scion

High Mg Low Mg

Shaddock Grapefruit Haas(15) Trifoliate orange 'Koethen' sweetorange Scion: 'Valencia' orange

Roughlemon Grapefruit Haas(16) Trifoliate orange Scion: Grapefruit

'Rusk' citrange Grapefruit Smith et al. (32) Roughlemon Sweetorange Scion: 'Valencia' orange

Roughlemon Grapefruit Wallaceet al. (36) Sour orange Scion: Various

'Cleopatra'mandarin Sour orange Gorton et at. (13) Scion: Grapefruit

'Cleopatra'mandarin 'Rangpur' sweetorange Joneset at. (20) Scion: Lemon

'T aiwanica' orange C. macrophylla Embleton et a/. (11) 'Yuzu' Citrusmoi Scion: Lemon

'Sun Chu Sha Kat' mandarin S.buxifolia Wutscheret al. (40) 'Cleopatra' 'Changsha'mandarin Scion: Grapefruit

'Tim kat' mandarin Grapefruit Wutscher and Shull (42) 'Cleopatra'mandarin Citrumelo C.P.B.4475 Scion: Grapefruit

ZINC

Rootstocks Reference& Scion

HighZn Low Zn

Grapefruit Sour orange Smith et al. (32) Roughlemon Sweetorange Scion: 'Valencia' orange

C61.251(Shekwasha x Koethen) C55-24-4 ('Cleopatra' x Trifoliate) Wutscher et al. (40) s. buxifolia 'Changsha' mandarin Scion: Grapefruit ,Abers' sour orange 'Tim kat' mandarin Wutscherand Shull (42) 'Bittersweet' sour orange 'Carrizo' citrange Scion: Grapefruit -105.

CALCIUM

Rootstocks Reference& Scion High Ca Low Ca

'Siamese'shaddock 'Koethen' sweet orange Haas(15) Trifoliate orange Rough lemon Scion: 'Valencia' orange

Sour orange 'lemon' Shaddock Haas(16) Trifoliate orange Roughlemon Scion: Grapefruit

Roughlemon Grapefruit Smith et a/. (32) 'Rusk' citran!)e Sweet orange Scion: 'Valencia' orange

'Cleopatra'mandarin Sour orange Gortonetal. (13) Scion: Grapefruit

'Cleopatra'mandarin 'Sampson'tangelo Jones et a/. (20) Roughlemon 'Rangpur' lime Scion: 'Eureka' lemon

Roughlemon Trifoliateorange Shannonand Zaphrir (28) Scion: Various

Grapefruit Yuzu Embletoneta/. (11) 'T aiwanica' orange C. macrophy//a Scion: Lemon

'Troyer' citrange Severinia buxifolia Wutscheret al. (40) 'Cleopatra'mandarin C55-24-4 ('Cletpatra' x trifoliate) Scion: Grapefruit

Sour orange Roughlemon Sharplesand Hilgeman(29) Scion: 'Valencia' orange

IRON

Rootstocks Reference& Scion Low Fe

'Rusk' citrange Grapefruit Smith et a/. (32) Roughlemon Sou r orange Scion: 'Valencia' orange

Roughlemon Trifoliate orange Wallace et a/. (37) Sour orange Grapefruit Scion: Lemon

Roughlemon Sour orange Kuykendall(21) Scion: Various

Roughlemon Trifoliate orange Shannonand Zaphrir (28) Scion: Various

'Rangpur' lime Embletonet al. (11) 'T aiwanica'orange Scion: lemon

C61.251(Shekwasha x Koethen) C55-24-4 ('Cle~atra' x Trifoliate) Wutscheret 81.(40) 'Cleopatra'mandarin C61.220 ('Cleopatra' x 'Troyer') Scion: Grapefruit 1011.

POTASSIUM

Rootstocks Reference& Scion

HighK LowK

'Koethen' sweet orange 'African' sour orange Haas(15) 'Sampson'tangelo Roughlemon Scion: 'Valencia' orange

Grapefruit Sour orange Haas(16) Shaddock Trifoliate orange Scion: Grapefruit

Grapefruit 'Rusk' citrange Smithet al. (32) Sweetorange Roughlemon Scion: 'Valencia' orange

Grapefruit Rough lemon Wallace et 81. (36) Sweetorange Sour orange Scion: Various

SOil r orange 'Cleopatra'mandarin Gortonef a/. (13) Scion: Grapefruit

'Rangpur'lime 'Cleopatra'mandarin Joneset a/. (20) 'Sampson'tangelo Scion: 'Eureka'iemon

Trifoliateorange Roughlemon Shannonand Zaphrir (28) Scion: Various

Severinia buxifolia 'Troyer' citrange Wutscher et al. (40) 'r.~ilam'rough lemon 'Sun Chu Sha Kat' mandarin Scion: Grapefruit

Grapefruit 'Carrizo' citrange Wutscher and Shull (42) Citrumelo C.P.B.4475 'Troyer' citrange Scion: Grapefruit

MANGANESE

Rootstocks Reference& Scion

High Mn Low Mn

'Cleopatra'mandarin Sweetorange Smith et a/. (32) Roughlemon Grapefruit Scion: 'Valencia' orange

'Yuzu' Sweetorange Embletonet al. (11) C. macrophylla Grapefruit Scion: Lemon s.buxifolia C55-24-4 ('Cleopatra'x Trifoliate) Wutscheret 81. (40) Sour orange Scion: Grapefruit

Roughlemon Sour orange Sharplesand Hilgeman(29) Scion: 'Valencia' orange

'Timkat' mandarin I Abers' sour orange Wutscherand Shull (42) 'Bittersweet' sour orange 'Carrizo' citrange Scion: Grapefruit 107-

NITflOGEN

Rootstocks Reference& Scion

HighN LowN

'Koethen' sweet orange 'African' sour rwange Haas(15) Roughlemon Trifoliate oran~ Scion: 'Valencia' orange

'Rusk'citrange 'Cleopatra' Smith et al. (32) Aou!Jhlemon Sourorange Scion: 'Valenciaorange Sweetoran!Je

Roughlemon Grapefruit Wallace et 01. (36) S~et orange Scion: various

Sour orange Trifoliate orange Wallaceet a/. (37) Scion: 'Eureka' lemon

Roughlemon Sour orange Sharplesand Hilgeman(29) Scion: 'Valencia' orange

Wutscher and Shull (42) 'Savage' citrange 'Troyer' citran~ Sour orange Scion: Grapefruit

PHO.9'HORtIS

Rootstocks Reference& Scion

HighP LowP

'Koethen' sweetorange 'Rubidoux' sour orange Haas(15) Trifoliate orange 'lemon' Shaddock Scion: 'Valencia' orange

Roughlemon 'Brazilian' sour orange Haas(16) Scion: Grapefruit Grapefruit Sour orange 'Lemon' Shaddock

Rough lemon Aldrich and Haas(1) Scion: Lemon

Sweetorange Sour orange Smith et a/. (32) 'Rusk'citrange 'Cleopatra'mandarin Scion: 'Valencia' orange

Roughlemon Sour orange Wallaceet 81. (36) Scion: various

Trifoliate orange Sour orange Wallaceet al. (37) Scion: 'Eureka' Grapefruit Sweetorange

S. buxifolia 'Kunenbo' Wutscherst a/. (40) Scion: Grapefruit Table 1. leaf levelsof 1 elementsof young grapefruit treeson 15 rontstocksand interstocks.

Scion Inter::tock Rootstcck %N* %K ~Ca %Mg ppm Mn ppm Ct- ppmB CES 3 Sourorange 2.06 cde\('* 1.07 bcd 3.66a 0.36 bc 20 de 550 c 150 bcd Nucellar Sour orange Sour orange 2.10 bcde 1.05 bcd 3.36ab 0.35 cd 20 de 565 c 162abcd Redblush Macrophylla Sour orange 2.01 de 1.25ab 3.80a 0.37 bc 19 e 647 c 157 bcd Grapefruit Cleopatra 1.96 e 0.87 cd 3.25abc 0.44ab 25 de 651 c 177ab Macrophvlla Cleopatra 2.07 bcde 0.81 d 3.31ab 0.468 26 cd 588 c 194a 2.26abc Macrophylla 1.17abc 2.98 bc 0.26 e 37ab 706 bc 137 cd Sour orange Macrophylla 2.01 de 1.25ab 2.92 bc 0.24 e 34ab 546 c 146 bcd Cleopatra Macrophylla 2.00 de 1.22abc 2.82 bc 0.25 e 34ab 711 bc 127 d Trifoliate Macrophylla 2.41a 1.31ab 2.89 bc 0.27 de 37ab 860abc 148 bcd Savage 2.31ab Macrophylla 1.35ab 2.73 c 0.23 e 38a 850abc 152 bcd Troyer 2.17abcde Macrophylia 1.27ab 2.99 bc 0.24 e 36ab 1065ab 141 cd £ glauca Hyb. 2.15 bcde Macrophylla 1.52a 2.99 bc 0.27 de 32 bc 1109a 136 cd Changsha 2.19abcde 1.08 bcd Macrophylla 2.92 bc 0.24 e 38a 815abc 152 bcd Owari Satsuma Macrophylla 2.12 bcde 1.26ab 2.85 bc 0.25 e 35ab 917abc 172abc Chinotto Macrophylla 2.24abcd 1.37ab 2.87 bc 0.26 e 34ab 748abc 157 bcd *Means of 4 determinationsbased on 8 trees.

Table2. Concentrationsof P, K, Ca,Mg, Mn, ln, and Cu in the leaves(dry weight) of 4-year-oldCES 3 Redblushgrapefruit treeson 16

Rootstock %P %K %Ca %Mg ppm Mn ppmZn ppmCu Texassour orange 0.108ba/ 0.98 ef 3.30abc 0.22 c 27 b 34ab 8b Kunenbo 0.105 b 0.91 f 3.45abc 0.25 bc 37 b 31 b 6 bc Cleopatra 0.117 b 1.11 def 3.64ab 0.33ab 38b 29bc 7bc C61.241,Shekwashax Rough lemon 0.112 b 1.32bcde 3.10bc 0.22 c 32 b 32 b 7 bc Changsha 0.110b 1.32bcde 3.00c e 0.20 c 30 b 28 bc Sun Chu Sha Kat 0.109 b 7bc 0.84 f 3.08bc O.37a 41 b 35ab 7 bc C61-250,Shekwasha x Koethen 0.112 b 1.56abc 2.9 c ef 0.23 c 36 b 30 b 8b Troyer 0.101 b 0.83 f 3.84a 0,27 bc 32 b 37ab 8b C61-253,Shekwasha x Chinotto 0.105 b 1.51abc 3.08 bc 0.33ab 37 b 34ab 7 bc C59.24,Rangpur x Trifoliate 0.121 b 1.02 ef 3.63ab 0.19 c 29 b 28 bc 8b C61-251,Shekwasha x Koetflen 0.098 b 1.44abcd 2.48 ef 0.21 c 41 b 43a 5 c C62.252,Shekwasha x Koethen 0.105 b 1.19 cdef 2.63 ef 0.35a 46 b 43a Milam 0.109 b 6 bc 1.60ab 3.20bc 0.22 c 41 b 30 b 8b C61-220,Cleopatra x Troyer 0.108h 1.07 def 2.51 ef 0.25 bc 30 b 26 c Severiniabuxifolia O.154a 6 bc 1.76a 2.50 ef 0.16 d 187a 38ab 13a C55-24-4,Cleopatra x Trifoliate 0.117 b 0.85 f 2.30 f 0.21 c 24 b 19 c 5 c a/Meanfollowed by letter "a" is significantly different (at the 5%level) from thosemeans not having"a"; thosefollowed by "b" aresignificantly different from thosenot having"b", etc.

From Wutscheret al. (40). 1"~.

Table3. Tree voillme, intensity of I:hlorosis,and concentrationof. iron, bnron, andchlorine in the leaves(dlV weight) of 4-year. old CES 3 Redblushgrapefruit treeson 16 rootstocksgrlIwing on calcareollssoil.

",:, :\\'\" Tree survival(%) Tree / Chlorosisb/ after 4 years volumea ..l91i!!R-~f!§L- fl~~n~~ -j~~~_o~JJ~J- -- m!- -- __~~A~_! y~g- _f~wRml_~JA~~_~l~JL.

Sour orange 100 4.92acl 0.0 c 1.0 c 77abcd 174bcd 0.09 cd Kunenbo 100 4.53a 0.8abc 1.0 c 61 bcde 212abc 0.10 bcd Cleopatra 100 421 ab 0.5 bc 0.8 c 84ab 197 bcd 0.08 d C61.241,Shekwasha x Roughlemon 86 2.83bc 1.0abc 1.8 bc 65 bcde 194bcd 0.11 bcd Changsha 100 2.79bc 2.0ab 1.3 c 59 cde 192bcd 0.09 cd Sun Chu Sha Kat 100 2.70 bc 2.0ab 2.0 bc 67 bcde 188bcd 0.11 bcd C61-250,Shekwasha x Koethen 100 2.70 bc 0.3 c 1.0 c 83abc 151 cde 0.11 bcd Troyer 86 2.66bc 0.5 bc 2.0 1M: 60 cde 178 bcd 0.23a C61-253,Shekwasha x Chinotto 71 2.55 bc 2.0ab 2.0 bc 59 cde 178 bcd 0.11 bcd C59.24,Rangptlr x Trifoliate 71 2.48 bc 0.0 c 1.8 bc 63 bcde 264a 0.10 bcd C61-251,Shekwasha x Koetllen 100 2.29 c n.o c 1.5 bc 94a 204abc 0.11 bcd C61-252,Shekwasha x Koethen 100 2.20 c 0.8abc 1.3 c 77abcd 205abc 0.10 bcd Milam 71 2.13 c 1.3abc 2.3 b 61 bcde 230ab 0.12 bc C61-220,Cleopatra x Troyer 100 2.07 c 1.5abc 2.3 b 58 de 158 cde 0.11 bcd Severiniabuxifolia 86 1.64 c 2.3a 2.3 b 65 bcde 100 c 0.11 bcd C55-24-4,Cleopatra x Trifoliate 100 1.42 c 1.3abc 3.5a 50 e 132 de 0.13a al Calculatedby the formula.YJi.cLttl.~~iJb1. 4

bID = all leavesgreen; 1 = trace of chlorosis;2 = mild chlorosis;3 ; moderatechlorosis; 4 = severechlorosis. c/Meanfollowed by letter "a" is significantly different (at the 5% level)from thosemeans not having"a"; thosefollowed by "b" are significantly different from those not having"b", etc,

From Wutscheret al. (40). -110-

rable 4. leaf analysis. Concentrations of 12 eleml~ntsin If!i!vescollecteri /\ugust 1971.

%N IP K %Ca ~:-;Mg ppm Fe ppm Mn ppm Zn ppnl Cli ppm Na ppm Cl ppm B

~ollrorange \bers 2.40 b* .12a .93cde 4.678 .33 de 68 a 33 cde 23 e 5a 1338ab 1299 bc 174 d 5a 777 c 793 cd 220 c ligaradier 2.46 b .12 a .84 cde 4.98a .35 d 70 a 38 bc 29 abcd littersweet 2.43 h .12 a .91 cd 5.07a .33 def 62 a 35 cde 32 ab 5a 592 c 539 d 194 d 'exassour orange 2.39 b .12a 1.02bcd4.76a .33 de 65 a 37 hcd 30 abcd 5a 1049bc 718d 172 d

'itranges :arrizo 2.54 b .13a .71e 4.69a .41 bc 66a 22 9 24e 48 1118ab 21188 217 c 'orton 2.43 b .11 a .81 cde 4.25a .39 c 65a 23 fg 28 bcde 58 698C 1464b 258 ab 29 ef 25 de 58 1000bc 1274bc 193d avage 2.81 a .14 a .94 cde 4.62a .33 de 67a 4a 1011bc 2022a 190d royer 2.34 h .12a .77d!' 4.89a .39 G 70" 23 fg 28 abcde itrumelo4475 2.50 h .13 a 1.23ah r'.33a .32 ef 67a 30 e 6a 794c 685d 198 cd 'andarins 763 c 689 d 238 b leopatra 2.44b .13a .81 r:de 4.~4a .43 b 59 a 42 ab 31 ab 5a onkan 2.38b .11a 1.03bc 4.P::Ia .39 c 56 a 31 de 31 ahc 5a 1430 ah 6"3 d 2778 imkat 2.47b .14 a .09 cde 4.21 a 50 a 62 a 41 a 33 a 5a 1598 a 490 d 233 bc

?edlings ~arv red 2.41b 14 a 1.34a 4.69 a .30 f 67 a 43 ab 29 ahcd 5a 1035bc 811cd 201cd ~rapefruit

~eanswithin a column followed by the sameletter are not significantly~ different at P"' 0.05 accordingto Duncan'sMultiple RangeTest.

rom Wutscher and Shull (42). -111.

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