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1986 The Response of Saccharum Species to Growth Regulators Used as Tillering Agents (Sugarcane). Keith P. Bischoff Louisiana State University and Agricultural & Mechanical College

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Bischoff, Keith P.

THE RESPONSE OF SACCHARUM SPECIES TO GROWTH REGULATORS USED AS TILLERING AGENTS

The Louisiana State University and Agricultural and Mechanical Ph.D. Col. 1986

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University Microfilms International THE RESPONSE OF SACCHARUM SPECIES TO GROWTH REGULATORS USED AS TILLERING AGENTS

A Dissertation

Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy

in

The Department of Agronomy

by Keith P. Bischoff B.S., Louisiana State University, 1976 December 1986 ACKNOWLEDGEMENTS

The author wishes to express his sincere appreciation to Dr.

Freddie Martin, Professor of Agronomy, Louisiana State University, for his guidance and help in conducting this study, and for his suggestions in the preparation of this dissertation.

Acknowledgements are also given to Dr. Edward P. Dunigan, Head,

Department of Agronomy, J. Preston Jones, former head, Department of

Agronomy, and the American Sugar Cane League for providing financial support for this study.

Special recognition and thanks are given to Jack Berg, Edwis

Dufrene and Joey Quebedeaux, Research Associates, and Kenneth Gravois and Scott Milligan, fellow graduate students, for their assistance throughout the course of this study.

The author would also like to extend gratitude to Veronica Taylor,

Research Associate, Department of Experimental Statistics; Dr. Benjamin

Legendre, Research Agronomist, U.S.D.A. Sugarcane Field Laboratory,

Houma, Louisiana; the staff of the St. Gabriel Research Station; and to

A. J. Williams for her help in preparing this document.

Finally, the most sincere appreciation is extended to the author's wife Beleta, daughter Kori Lynn and parents Frank and Lucia for their patience and constant encouragement without which this dissertation would not have been possible. TABLE OF CONTENTS

Topic Page

ACKNOWLEGEMENTS...... ii

LIST OF TABLES ...... iv

LIST OF FIGURES ...... vi

ABSTRACT ...... ix

PART I. TILLERING AGENT BY GENOTYPE INTERACTION ...... 1

INTRODUCTION ...... 2

REVIEW OF LITERATURE...... 4

Plant Growth Regulators and Sugarcane ...... 5

MATERIALS AND METHODS...... 8

RESULTS AND DISCUSSION ...... 14

Plant Cane Results...... 14

Ratoon Results...... 25

Overall Discussion...... 59

SUMMARY AND CONCLUSIONS...... 66

PART II. BEHAVIOR OF TILLERING RESPONSE TO ETHEPHON TREATMENT IN TWO SEGREGATING POPULATIONS...... 68

INTRODUCTION ...... 69

MATERIALS AND METHODS ...... 70

RESULTS AND DISCUSSION...... 73

SUMMARY AND CONCLUSIONS...... 81

REFERENCES...... 82

APPENDIX ...... 84

VITA ...... 87

iii LIST OF TABLES

PART ONE Page

Table 1. Sa.ccha.rtm species and respective cultivar designations which were utilized in the testing of plant growth regulators as tillering agents...... 9

Table 2. Growth regulators tested for ability to increase tillering in Saccharua species and their rates of application ...... 10

Table 3. The analysis of variance for mean shoot number data of the plant cane experiments ...... 15

Table 4. Effects of growth regulators on mean number of shoots produced by cultivars of different Saccharuzn species in the plant cane experiment...... 16

Table 5. Growth regulator treatment effects on Saccharua species as indicated by mean shoot number and percent increase over the check in plant c a n e ...... 18

Table 6. Mean heights of untreated plants for the fourteen cultivars of the four Saccharua species, after eight weeks, in the plant cane experiment...... 20

Table 7. Analysis of variance for difference in height measurements for plant c a n e ...... 22

Table 8. Difference in height (DHT) measurements for the variety by treatment interaction of Saccharua cultivars in experiment one ...... 23

Table 9. Difference in height (DHT) measurements for the variety by treatment interaction of Saccharua cultivars in experiment t w o ...... 24

Table 10. Analysis of variance for mean shoot number of the ratoon experiment ...... 40

Table 11. The variety by treatment interaction for mean number of shoots produced by plants of cultivars of different Saccharua species in the ratoon experiment...... 41

Table 12. Growth regulator treatment effects on Saccharua species as indicated by mean shoot number and percent increase over the check in the ratoon experiment...... 43

Table 13. Mean heights for fourteen untreated cultivars of four Saccharua species in the ratoon experiment...... 60 iv Table 14. Analysis of variance for difference in height measurement for the ratoon experiment ...... 61

Table 15. Difference in height (DHT) measurements for variety by treatment interaction of Saccharua cultivars in the ratoon experiment ...... 62

Table 16. Correlation coefficients showing the relationship of mean height of the untreated species to mean number of shoots of the treated species in the plant cane and ratoon experiments ...... 65

PART TWO

Table 1. Parentage of the half-sib families utilized in the study of ethephon response...... 71

Table 2. Analysis of variance table for mean shoot number data of parental cultivars taken on day 5 6 ...... 74

Table 3. Mean number of shoots produced by each parental cultivar comparing treated vs. untreated plants.... 74

Table 4. Analysis of variance for mean shoot number data of each half-sib family taken on day 56 ...... 75

Table 5. Mean number of shoots produced by each half-sib family comparing treated vs. untreated plants ...... 75

APPENDIX

Table 1. Effects of growth regulators on mean number of shoots produced by cultivars of different Saccharum species in experiment one...... 85

Table 2. Effects of growth regulators on mean number of shoots produced by cultivars of different Saccharum species in experiment two...... 86

v LIST OF FIGURES

PART ONE Page

Figure 1. The effect of five plant growth regulators on the height of the Saccharins officinarum cultivar Cavengerie in the plant cane experiment...... 26

Figure 2. The effect of five plant growth regulators on the height of the Saccharum officinarum cultivar Cristalina in the plant cane experiment...... 27

Figure 3. The effect of five plant growth regulators on the height of the Saccharum officinarum cultivar IS 76-514 in the plant cane experiment...... 28

Figure 4. The effect of five plant growth regulators on the height of the Saccharum officinarum cultivar Louisiana Striped in the plant cane experiment .... 29

Figure 5. The effect of five plant growth regulators on the height of the Saccharum sinense cultivar Katha in the plant cane experiment...... 30

Figure 6. The effect of five plant growth regulators on the height of the Saccharum sinense cultivar Chunnee in the plant cane experiment...... 31

Figure 7. The effect of five plant growth regulators on the height of the Saccharum robustum cultivar NG 77-132 in the plant cane experiment...... 32

Figure 8. The effect of five plant growth regulators on the height of the Saccharum robustum cultivar NG 77-160 in the plant cane experiment...... 33

Figure 9. The effect of five plant growth regulators on the height of the Saccharum robustum cultivar NG 77-76 in the plant cane experiment...... 34

Figure 10. The effect of five plant growth regulators on the height of the Saccharum robustum cultivar NG 77-136 in the plant cane experiment ...... 35

Figure 11. The effect of five plant growth regulators on the height of the Saccharum spontaneum cultivar Mandalay in the plant cane experiment...... 36

vi Figure 12. The effect of five plant growth regulators on the height of the Saccharum spontaneum cultivar SES 513 in the plant cane experiment...... 37

Figure 13. The effect of five plant growth regulators on the height of the Saccharum spontaneum cultivar SES 577 in the plant cane experiment...... 38

Figure 14. The effect of five plant growth regulators on the height of the Saccharum spontaneum cultivar SES 205-A in the plant cane experiment...... 39

Figure 15. The effect of five plant growth regulators on the height of the Saccharum officinarum cultivar Cavengerie in the ratoon experiment...... 45

Figure 16. The effect of five plant growth regulators on the height of the Saccharum officinarum cultivar Cristalina in the ratoon experiment...... 46

Figure 17. The effect of five plant growth regulators on the height of the Saccharum officinarum cultivar IS 76-514 in the ratoon experiment...... 47

Figure 18. The effect of five plant growth regulators on the height of the Saccharum officinarum cultivar Louisiana Striped in the ratoon experiment ...... 48

Figure 19. The effect of five plant growth regulators on the height of the Saccharum sinense cultivar Katha in the ratoon experiment...... 49

Figure 20. The effect of five plant growth regulators on the height of the Saccharum sinense cultivar Chunnee in in the ratoon experiment . . . ‘...... 50

Figure 21. The effect of five plant growth regulators on the height of the Saccharum robustum cultivar NG 77-132 in the ratoon experiment...... 51

Figure 22. The effect of five plant growth regulators on the height of the Saccharum robustum cultivar NG 77-160 in the ratoon experiment...... 52

Figure 23. The effect of five plant growth regulators on the height of the Saccharum robustxm cultivar NG 77-76 in the ratoon experiment...... 53

Figure 24. The effect of five plant growth regulators on the height of the Saccharum rohustum cultivar NG 77-136 in the ratoon experiment...... 54 vii Figure 25. The effect of five plant growth regulators on the height of the Saccharum spontaneum cultivar Mandalay in the ratoon experiment . 55

Figure 26. The effect of five plant growth regulators on the height of the Saccharum spontaneum cultivar SES 513 in the ratoon experiment...... 56

Figure 27. The effect of five plant growth regulators on the height of the Saccharum spontaneum cultivar SES 577 in the ratoon experiment...... 57

Figure 28. The effect of five plant growth regulators on the height of the Saccharum spontaneum cultivar SES 205-A in the ratoon experiment...... 58

PART TWO

Figure 1. The frequency distribution, as percent of total, of seedlings of the cross CP 65-357 X Mandalay as a function of shoot number ...... 76

Figure 2. The frequency distribution, as percent of total, of seedlings of the cross CP 65-357 X SES 231 as a function of shoot number ...... 78

Figure 3. The frequency distribution, as percent of total, of seedlings of the cross CP 65-357 X Mandalay as a function of DHT measurements...... 79

Figure 4. The frequency distribution, as percent of total, of seedlings of the cross CP 65-357 X SES 231 as a function of DHT measurements...... 80

viii ABSTRACT

This study was conducted to identify those plant growth regulators

that cause the greatest increase in shoot number of basic genotypes of

the genus Saccharum and at the same time identify those genotypes that

exhibit a high degree of response to certain growth regulators which have been proposed as tillering agents.

A series of three factorial experiments was conducted under

controlled conditions in the greenhouse utilizing fourteen cultivars

representing the spectrum of the genus Saccharum along with five synthetic growth regulators proposed as tillering agents.

Treatments were applied to the plants one month after germination.

Shoot number and shoot height measurements were taken every two weeks, beginning two weeks after planting, for a period of eight weeks.

Plants treated with (2-chloroethyl) phosphonic acid (ethephon) produced the highest number of shoots and showed increased growth rate.

The (2-chloroethyl) trimethylanunonium chloride (chlormequat) and poly[oxyethylene(dimethyliminio)ethylene (diraethyliminio) ethylene- dichloride] (bualta) treatments resulted in an increase in shoot production with no effect on plant vigor. One-napthaleneacetic acid

(NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) increased shoot number but plant vigor was decreased.

Certain combinations of S. spontaneum or S. sinense cultivars with ethephon, chlormequat or bualta, resulted in an increase in shoot number over the check, with no effect on plant vigor. A genetic study was also conducted to determine if the characteristic of response to ethephon by progenies of cultivars of S. spontaneum and

CP65-357 crosses was under genetic control.

Total shoot number and growth rate were increased in the parental cultivars and their progenies through the use of ethephon as a tillering agent. Unfortunately, differences in response of the half-sib families and their respective parents were not detected in the genetic study.

However, the rather large differences in shoot number and growth rate among genotypes in response to ethephon in both plant and ratoon cane evaluated in part one this study, suggest that this characteristic of response is under genetic control.

x PART I. TILLERING AGENT BY GENOTYPE INTERACTION INTRODUCTION

Over the past 30 years, significant progress has been made in

increasing the yield of sugar per hectare in Louisiana sugarcane through breeding (3).

The yield of sugar per hectare has two major components: yield of sugarcane per hectare and yield of sugar per unit of sugarcane. The genetic progress made in increasing sugar per hectare has come mainly from increases in sugar per unit of sugarcane (3). Little genetic progress has been made in increasing the yield of sugarcane per hectare of cultivars in Louisiana. Therefore, it is important that research be done to find means of increasing yield of sugarcane per hectare.

The yield of sugarcane per hectare has two major components: average stalk weight and number of millable stalks per hectare.

Previous studies have shown a positive relationship between yield of sugarcane per hectare and number of millable stalks per hectare (15).

Therefore, a means of increasing yield of sugarcane per hectare would be to increase the number of millable stalks per hectare. This becomes especially important in the later ratoon crops when the yield of sugar­ cane per hectare decreases.

The Louisiana sugarcane breeding programs are currently using high population parents as the primary means of increasing millable stalk number in Louisiana sugarcane cultivars. The study reported herein was initiated to investigate a possible means of supplementing the use of high population parents with synthetic growth regulators proposed as tillering agents to increase millable stalk number. This study was designed to identify those tillering agents that cause the greatest increase in shoot number without affecting the growth rate of the treated plants and to identify those basic genotypes of the genus Saccharum which exhibit the highest degree of response to certain chemicals used as tillering agents. Once identified, these genotypes could possibly be used in the breeding program to develop cultivars which may exhibit response to tillering agents. The yield of such cultivars may be enhanced by the treatment. An increase in yield, especially in the later ratoons, through the application of a tillering agent would be of great importance to the sugar industry. REVIEW OF LITERATURE

Weaver (26) defines a plant growth regulator as an organic exogenous growth substance which when applied to the plant in small amounts, promotes, inhibits or otherwise modifies any plant physiological process.

Nickell (21) defines plant growth regulators as either natural or synthetic compounds that are applied directly to a target plant to alter its life processes or its structure to improve quality, increase yields or facilitate harvesting. Nickell (21) also states that chemicals controlling plant growth have long been treated like a poor relation of the herbicides yet, in a manner of thinking, herbicides are a part of plant growth regulation.

The first plant growth regulators isolated were the auxins in 1928.

Hitchcock and Zimmerman (8) reported the first practical uses of growth regulators as stimulating root formation and promoting flowering in pineapple with acetylene and ethylene. In 1944, 2,4-D was introduced as a herbicide, and the importance of these chemicals to agriculture was realized. Since then, herbicides have been the most widely used plant growth regulators. Recently, additional economically important uses have been discovered for plant growth regulators in agriculture. Such things as enhanced fruit set and development, chemical pruning, plant shaping, dessication, abscission, ripening, increasing plant and organ size, etc., have been achieved through the use of growth regulators.

The promotion of tillering with growth regulators has been reported in barley, by Leopold (13) and Jewiss (10). Nickell (21) cites Langer and Chang for work done on promoting tillering in wheat and rice,

respectively.

Plant Growth Regulators and Sugarcane

According to Nickell (20), plant growth regulators have been used

for over twenty years by the sugarcane industry to increase the

recoverable sugar yield of sugarcane. Nickell (22) also reports the

first commercial success was in the prevention of flowering, followed by

the application of gibberellic acid for the increase of stalk elongation which ultimately resulted in increased sugar production. Currently, the primary interest centers around the use of chemicals for the control of maturation - the so called chemical "ripeners". Bull (4) in Australia

and Nickell and Tanimoto (19) in Hawaii were among the first to report

findings on this subject.

Barnes (1) describes tillering as; when the primary shoot grows, the

stem forms very short joints, on the nodes of which the small buds near

the bottom swell and develop secondaries which produce their own root

system, and these in turn may develop tertiary shoots in a similar manner, and so on. This process of underground branching or tillering

results in a number of cane stalks, forming a stool.

Van Dillewijn (6) similarly states that soon after planting, the buds of a cutting start developing shoots. These are the so called mother shoots or primaries. The little stem of these primaries consists

of many short internodes, each of which carries a lateral bud. These buds give rise to the development of secondary shoots which in their

turn may produce tertiary shoots, etc. Thus the mode of tillering may become rather intricate. Van Dillewijn (6) also lists factors

influencing tillering as: light, temperature, fertilizers, moisture, spacing, earthing up, lodging, diseases and pests, thinning, planting time and compensation.

Benda (2) states that sugarcane has two periods of growth; tillering occurs in the early period when the primary shoot grows from soil to air. Unless injured, diseased or flowering, no further tillering occurs in Louisiana.

Leopold (14) reported that since the auxin level in a plant or a branch of a plant is a primary factor in the inhibition of lateral buds, treatments which would reduce the auxin level should stimulate branching. Burg and Burg (5) indicated ethrel causes a release of ethylene in plant tissue which stimulates peroxidase activity leading to the destruction of endogenous auxins which inhibit bud germination.

Warner and Leopold (25) found that high concentrations of exogenous auxin induce the synthesis of ethylene which breaks apical dominance.

Loh and Tseng (15) concluded that the number of tillers produced per stool of sugarcane greatly determines the yield of millable canes per unit of area. Legendre (12) in Louisiana, and Mariotti (18) in

Argentina obtained significant positive associations between cane yield and stalk number. James (9) in Florida stated that stalk number was the most important yield component when he subjected data to path-coefficient analysis.

Increased tillering of sugarcane cultivars in plants grown from seed pieces treated with ethephon was reported by Takahashi (24) in Hawaii and Eastwood (7) in Jamaica, Eastwood reported a high level of tillering in two of three clones tested, whereas the third showed no response.

Lucchesi (16), in Brazil, showed no effect of ethephon in the plant crop but a significant increase in the number of millable stalks in the ratoon crop. Kanwar and Haimidder (11) improved the sprouting of ratoon crops when the stubble was sprayed with growth regulators after cutting. In the Philippines, Madrid and Rosario (17) significantly increased tiller formation with ethephon at high concentrations and bualta at low concentrations. In Taiwan, Pao (23) stimulated tillering with ethephon and chlormequat, while Yang, Ho and Wei (28) increased tillering in ratoon crops with IBA and ethephon. Ethephon was found to be the most effective tillering agent in Louisiana by Wong-Chong and Martin (27). MATERIALS AND METHODS

A series of three factorial experiments were conducted from

November, 1983 through August, 1984. Four cultivars each of Saccharum officinarum, S. robustum and S. spontaneum along with two cultivars representing S. sinense were selected to represent the spectrum of the genus Saccharum (Table 1). Five synthetic growth regulators and a check were used as the six treatments (Table 2).

The study included three experiments conducted under controlled conditions in the greenhouse. Precautions were taken to avoid insect damage, breakage of shoots, chemical drift or any other outside source that might promote tillering.

Due to the genetic diversity of the basic lines grown, the length of time between the planting of bud cuttings and emergence of the first shoots varied greatly from cultivar to cultivar. A preliminary study was therefore conducted to determine the respective lengths of time to emergence of the first shoots for each cultivar. Based on this study, the planting dates of the cultivars in the actual experiments were staggered. The slower germinating cultivars were planted first and the faster ones last, resulting in all cultivars germinating at approximately the same time. By following this planting procedure, it was possible to apply the growth regulator treatments to all cultivars at approximately the same stage of growth beyond germination.

Experiment one was planted in November of 1983. Single bud cuttings of each cultivar were germinated. The 24 best plants of each cultivar were selected for the experiment to accommodate the six treatments replicated four times. The bud cuttings were germinated in 8 9

Table 1. Saccharum species and respective cutlivar designations which were utilized in the testing of plant growth regulators as tillering agents.

SPECIES CULTIVARS

Saccharum officinarum Cavengerie Saccharum officinarum Cristalina Saccharum officinarum IS 76-514 Sacchanm officinarum Louisiana Striped Saccharum sinense Katha Saccharum sinense Chunnee Saccharum robustum NG 77-132 Saccharum robustum NG 77-160 Saccharum robustum NG 77-76 Saccharum robustum NG 77-136 Saccharum spontaneum Mandalay Saccharum spontaneum SES 513 Saccharum spontaneum SES 577 Saccharum spontaneum SES 205-A 10

Table 2. Growth regulators tested for ability to increase tillering in Saccharum species and their rates of application.

COMMON NAME CHEMICAL NAME RATE

Untreated Check NAA 1-Napthaleneacetic Acid 100ppm„ 2,4-D 2,4-Dichlorophenoxyacetic Acid 250ppm Bualta Poly[oxyethylene(dimethyliminio)ethylene 3 (dimethyliminio)ethylenedichloride] 200ppm- Ethephon (2-Chloroethyl) Phosphonic Acid 500ppm- Chlormequat (2-Chloroethyl) Trimethylammonium Chloride 200ppm

*Kanwar, R.S. and K. Haimidder. Improving Sprouting of Stubble Crops in Low Temperature Areas. ISSCT XVI Proceedings, 1977. pp. 1325-1331. 2 Nickell, L.G. 1982. Sugarcane, Plant Growth Regulating Chemicals, CKC Press, Boca Raton, FL. 7:186, 3 Madrid, P.V. and E.L. Rosario. 1979. Chemicals on the Tillering Ability of Variety Phil 56-226. Sugarland, vol. 16(2). pp. 11-12. 11

33.75cm X 66.56cm styrofoam Todd Planter Trays*; each tray having

eighteen 10cm X 10cm X 10cm cells. The cells were filled with Jiffy-Mix 2 Plus . One bud cutting was placed in each cell. The staggered planting

date procedure was employed to synchronize germination. After germi­ nation, the cultivars were transplanted into 11.32 liter plastic pots

containing a mixture of equal amounts of Commerce Silt Loam soil, and peat moss. Initially the pots were arranged in six groups of 56 to

facilitate treatment application. Each group contained the 14 cultivars

replicated four times. Each group was placed in a separate area of the

greenhouse to avoid drift of the treatments during application. The

cultivars then grew for one month, after which the chemical treatments were applied. A back-pack type sprayer was used to apply the growth

regulator mixtures to the foliage of the plants until run-off occurred.

When dry, the pots were rearranged into a completely randomized design in one area of the greenhouse.

Experiment two was planted in June of 1984. The bud cuttings used

for this experiment were cut from the untreated check pots in experiment

one. As in experiment one, 24 plants of each cultivar were selected.

The planting and germination procedure was the same as that in experiment

one. However, in experiment two the entire experiment was conducted in

styrofoam trays. The trays were arranged in six groups of 56 cells, or

four trays per group at planting. Four replicates of the 14 cultivars were planted in each group where they remained until the treatments were

*Speedling Incorporated, P. 0. Box 238, Sun City, FL 33586. 2 Jiffy Products of America, 250 Town Road, West Chicago, IL 60185. 12

applied. Upon drying, all 24 trays were placed in one group and the plants were rearranged within the cells of the group into a completely

randomized design. The cultivars remained in the styrofoam trays for the

duration of the experiment.

The third experiment also was initiated in June of 1984. All cane

in the 11.32 liter containers of experiment one was harvested and a

"ratoon crop" was allowed to grow. The pots were again placed into six

groups as in experiment one for one month after which the treatments were

applied. After the foliage dried, the pots were rearranged into a

completely randomized design in the greenhouse.

Variation of watering, fertilization, temperature, etc. within and between experiments was kept to a minimum. A strict watering and fertiliza­ tion schedule was followed in all experiments. Temperature was thermostati­

cally controlled in the greenhouse. One variation which was not

controlled was the difference in day-length. The first experiment was performed during the winter when day-lengths ranged from 10 hrs. 10 min.

to 10 hrs. 26 min. Experiment two and the ratoon experiment were carried out during the summer when day-lengths ranged from 13 hrs. 30 min. to 14 hrs. 8 min.

Measurements of height and total shoot number for individual plants of each cultivar in each pot were taken every two weeks from the time of germination until the rate of tillering had slowed or ceased (eight weeks). Height measurements were taken in centimeters from the soil

line to the uppermost visible dewlap of the tallest shoot. Growth rate was determined by subtracting the height on day 14 from the height on

day 56. This resulted in a difference in height (DHT) measurement which

gives the best indication of the growth rate of the plants. The shoot height, DHT and shoot number variables for each experi­ ment were analyzed as a completely randomized design with a factorial arrangement of treatments using the general linear models (GLM) procedure 3 (SAS) . An analysis of variance was calculated on the mean height and mean shoot number measurements taken at eight weeks on both untreated and treated cultivars, and DHT measurements. Based on these analyses of variance, the means were separated by protected LSD tests.

The analysis of height and DHT measurements were used primarily to determine if there were effects on the growth rate of the cultivars by the treatments. Shoot count analysis was used to determine if there was a greater degree of tillering of the cultivars caused by the treatments.

3 SAS Institute, Inc. SAS User's Guide: Statistics, 1982 Edition. Cary, NC SAS Institute Inc., 1982. 584 pp. RESULTS AND DISCUSSION

Plant Cane Results

Because of the similarity of mean shoot number results from experiments one and two (see Appendix Table 1 and Table 2), these data were combined for analysis. The interactions of test by cultivar and test by treatment were highly significant, however, the mean squares involving these interactions were relatively small compared to the main effects mean squares. The results of the plant cane analysis of variance for mean shoot number data are shown in Table 3. All main effects were significant along with the test by cultivar, test by treatment and cultivar by treatment interactions. Based on the combined analysis, means were separated by protected LSD tests.

In Table 4, the cultivar by treatment interaction of the plant cane, the degree of tillering of each cultivar as influenced by each treatment is indicated. In SES 513, all growth regulators tested caused an increase in mean shoot number over the check. The ethephon treatment caused the highest mean number of shoots to be produced by SES 513, with

NAA and chlormequat being similar. The 2,4-D treatment was lower than ethephon in mean shoot number produced by this cultivar but was not different from NAA, chlormequat and bualta.

The ethephon, chlormequat and bualta treatments induced a higher degree of tillering than the check in SES 577, Chunnee, and Cristalina.

The effects of 2,4-D and NAA on these cultivars were not different from the check.

14 15

Table 3. The analysis of variance for mean shoot number data of the plant cane experiments.

SOURCEDF MEAN SQUARE

Test 1 27.33 Cul 13 105.10 ** Test*Cul 13 5.33 ** Trt 5 30.47 ** Test*Trt 5 4.33 ** Cul*Trt 65 1.38 ** Test*Cul*Trt 65 0.85 Error 498 0.71

TOTAL 665

*** significant at the .01% level of probability Table 4. Effects of growth regulators on mean number of shoots produced by cultivars of different Saccharum species in the plant cane experiment

SPECIES CULTIVARCHECK ETHEPHONCHLORMEQUATBUALTA 2,4-D NAA

S . spontaneurn SES 513 4.25 6.88 6.50 5.63 5.88 6.63 S . spontaneum SES 577 4.00 5.75 5.38 4.88 4.62 4.25 S . spontaneum SES 205-A 3.54 5.67 5.17 4.37 4.54 3.67 S . spontaneum Mandalay 3.38 4.50 4.50 3.88 3.88 4.50 S. sinense Chunnee 2.63 4.38 3.88 3.50 3.25 2.88 S. sinense Katha 2.50 4.25 3.25 2.88 2.50 1.88 S. robustum NG 77-132 2.00 4.00 4.25 2.50 2.25 2.38 S. robustum NG 77-136 2.13 3.38 2.75 2.88 2.88 2.13 S . robustum NG 77-160 1.00 1.75 2.50 1.38 1.13 1.38 S . robustum NG 77-76 1.00 1.00 1.00 1.00 1.00 1.00 S. officinarum Cavengerie 1.25 2.88 2.38 1.88 2.63 1.88 S. officinarum Cristalina 1.13 2.63 2.88 2.00 1.13 1.38 S. officinarum IS 76-514 1.63 2.25 1.38 1.63 1.00 1.00 S. officinarum Louisiana Striped 1.00 2.00 1.38 1.38 1.38 1.13

OVERALL MEANS 2.23 3.67 3.37 2.83 2.70 2.57

1LSD @ .05 = 0.83 17

The cultivars SES 205-A and Cavengerie, when treated with ethephon, chlormequat and 2,4-D, produced higher mean shoot numbers than when left untreated. Bualta and NAA showed no effect on these cultivars.

Mandalay responded to chlormequat, ethephon and NAA by producing more shoots under these treatments than when left untreated. Bualta and

2.4-D had no effect on this cultivar.

Chlormequat and ethephon caused NG 77-132 to produce a higher mean number of shoots than the check. In this cultivar, the bualta, NAA and

2.4-D treatments had no effects.

NG 77-136 and Louisiana Striped responded to only ethephon. All other treatments caused a production of shoots not different from the check.

Only chlormequat caused a increase in shoot number over the check in the cultivar NG 77-160. No other regulator tested induced tillering in this cultivar any different from the check.

In IS 76-514 and NG 77-76, no growth regulator treatments caused a response different from the check. All plants of NG 77-76 in the plant cane experiments produced only one shoot.

In Table 5, the increase in mean shoot number over the check resulting from treatment effects can be seen for each species. The increases are indicated by mean shoot number and percent increase over the check.

Ethephon resulted in the highest average percent increase of all growth regulators tested having a range of 50.4 percent increase over the check in S. spontaneum to 95.2 percent increase in 5. officinarum.

The effects of ethephon on S. officinarum were about two times greater than those on S. spontaneum. However, the increase in mean shoot Table 5. Growth regulator treatment effects on Saccharum species as indicated by mean shoot number and percent increase over the check in plant cane.

INCREASE IN SHOOT NUMBER OVER THE CHECK1 MEAN NUMBER OF SPECIES SHOOTS OF CHECK ETHEPHONCHLORMEQUAT BUALTA 2,4-D NAA

5. spontaneum 3.79 1.91(50.4) 1.60(42.2) 0.90(23.7) 0.94(24.8) 0.97(25.6) S. sinense 2.57 1.75(68.1) 1.00(38.9) 0.62(24.1) 0.31(12.1) -0.19(-7.0) S . robustxm 1.53 1.00(65.4) 1.10(71.9) 0.41(26.8) 0.29(19.0) 0.19(12.4) S. officinarum 1.25 1.19(95.2) 0.76(60.8) 0.47(37.6) 0.29(21.6) 0.10( 8.0)

OVERALL % INCREASE (69.8) (53.5) (28.1) (19.4) ( 9.8)

Percent increases in parenthesis 19 number was reversed. Ethephon caused S. spontaneum to produce an average of 1.91 more shoots per plant than the check, while the S. officinarum plants averaged only 1.19 more shoots per plant than the check. The case was the same in the chlormequat and bualta treatments. The higher percent increases over the check by S. robustum and S. officinarum cultivars had lower mean shoot number increases than S. spontaneum.

These results were due to the higher mean shoot numbers of the check of

S. spontaneum.

Both ethephon and chlormequat were more effective than the other growth regulators tested in causing an increase in mean number of shoots in all species tested.

Saccharum spontaneum responded to all treatments tested as indicated by the percent increase caused by each growth regulator over the check.

Ethephon and chlormequat resulted in the highest percent increase over the check in S. sinense. Plants of S. sinense treated with NAA produced fewer shoots than the check. Cultivars of $. robustum and S. officinarum showed a higher degree of response when treated with ethephon and chlormequat than with any other growth regulator.

Each growth regulator tested on plant cane resulted in an increase in mean shoot number over all cultivars. However, it was not known if this increase was at the expense of the growth rate of the plants.

Therefore, the effects of the tillering agents on the growth rate of the treated plants were also researched.

Height measurements were taken every two weeks for the duration of the experiment to determine the effect of the treatments on growth rate.

The check cultivars were compared and ranked according to mean height and a protected X.SD was used to separate the means. These results are presented in Table 6. 20

Table 6. Mean heights of untreated plants for the fourteen cultivars of the four Saccharum species, after eight weeks, in the plant cane experiment.

SPECIES CULTIVAR MEAN HEIGHT (cm)

S. spontaneum Mandalay 95.81 5. spontaneum SES 577 68.00 S . spontaneum SES 513 65.06 S . sinense Katha 43.06 S . sinense Chunnee 40.06 S. robustum NG 77-76 34.94 S . spontaneum SES 205-A 30.86 S. officinarum Cristalina 26.19 s. robustum NG 77-132 24.88 S . officinarum Louisiana Striped 24.69 S . robustum NG 77-136 24.31 S . officinarum Cavengerie 23.00 S . officinarum IS 76-514 22.31 S. robustum NG 77-160 21.69

LSD @ .05 = 5.73 21

Mandalay was the tallest of all cultivars tested, followed by SES

577 and SES 513. NG 77-132, Louisiana Striped, NG 77-136, Cavengerie, IS

76-514 and NG 77-160 were all statistically equal to each other in mean height and shorter than all other cultivars tested.

Because of the differences in height between cultivars and the fact that some plants were taller than others within cultivars on day 14, the variable for difference in height (DHT) was created. This measurement gave a better indication of the effects of the treatments on the growth rate of the plants. The mean height on day .14 was subtracted from the mean height on day 56 resulting in a difference in height measurement

(DHT) for each treatment within each cultivar. An analysis of variance was then run on the DHT data and the results are presented in Table 7.

Due to the significance of the main effect of test and all interactions involving the test effect, DHT data from each experiment were analyzed separately.

In Table 8, the effects of each treatment on the growth rate of each cultivar in experiment one are presented.

Ethephon caused a reduction in the growth rate of IS 76-514. In the cultivar Mandalay, bualta and 2,4-D resulted in a positive response as indicated by higher DHT measurements.. Bualta reduced the growth rate of SES-513. No other effects on growth rate were observed in the first experiment.

Table 9 indicates the effects of treatment on the growth rates of cultivars in experiment two. Ethephon caused an increase in the growth rate of NG 77-132, NG 77-76, NG 77-160 and Chunnee. Mandalay responded negatively to ethephon treatment. A reduction in the growth rates of

Katha, NG 77-76, Mandalay, SES 513 and SES 577 were observed when the Table 7. Analysis of variance for difference in height measurements for plant cane.

SOURCE DF MEAN SQUARES

Test 1 1933.26 *** Cul 13 11442.54 ** Test*Cul 13 1431.94 ** Trt 5 558.55 ** Test*Trt 5 649.59 ** Cul*Trt 65 48.46 ** Test*CuI*Trt 65 48.22 ** Error 498 22.50

TOTAL 665

*** significant at the .01% level of probability Table 8. Difference in height (DHT) measurements* for the variety by treatment interaction of Saccharum cultivars in experiment one

SPECIES CULTIVAR CHECKETHEPHONCHLORMEQUATBUALTA 2,4-D NAA

S. spontaneum Mandalay 45.25 48.88 47.50 51.00 54.25 44.88 S. spontaneum SES 513 21.50 19.75 19.63 12.75 20.75 19.50 S. spontaneum SES 577 42.00 39.63 45.00 44.50 41.63 38.88 S. spontaneum SES 205-A 13.50 14.33 16.50 17.50 16.83 13.17 S. sinense Katha 18.75 19.00 18.75 19.38 18.50 21.25 s. sinense Chunnee 18.38 20.00 18.75 17.75 17.75 18.13 s. robustum NG 77-132 11-25 8.75 10.25 9.00 9.63 9.88 s. robustum NG 77-160 10.00 8.63 9.38 10.13 7.88 9.63 s. robustum NG 77-76 19.38 19.13 19.75 19.13 18.63 19.88 s. robustum NG 77-136 9-38 10.63 9.13 10.13 12.00 11.75 s. officinarum Cavengerie 10.13 9.00 10.38 8.88 9.25 8.88 s. officinarum Cristalina 12.38 11.50 10.75 10.88 11.50 10.75 s. officinarum IS 76-514 10.88 6.00 8.38 6.75 9.88 7.13 s. officinarum Louisiana Striped 11.75 12.13 12.38 11.13 10.75 10.00

*DHT = height on day 14 subtracted from height on day 56

2LSD @ .05 = 4.82

N> Table 9. Difference in height (DHT) measurements* for the variety by treatment interaction of Saccharum 2 cultivars in experiment two

SPECIESCULTIVARCHECK ETHEPHONCHLORMEQUAT BUALTA 2,4-D NAA

S . spontaneum Mandalay 73.63 62.38 63.63 68.00 48.88 49.13 S . spontaneum SES 513 61.00 59.75 52.25 55.38 44.38 55.13 S . spontaneum SES 577 54.88 57.25 54.38 51.00 25.50 55.10 S . spontaneum SES 205-A 21.50 28.75 25.75 24.75 19.50 21.75 S. sinense Katha 27.25 33.75 23.13 25.25 11.13 19.63 S. sinense Chunnee 20.38 35.38 23.13 24.38 12.88 15.00 S . robustum NG 77-132 9.00 23.63 9.38 7.00 5.25 5.25 S . robustum NG 77-160 9.38 22.63 7.75 8.00 6.13 7.00 S . robustum NG 77-76 18.63 28.50 14.63 15.00 7.25 11.88 S . robustum NG 77-136 4.00 8.63 2.00 3.63 4.00 3.25 S. officinarum Cavengerie 10.88 8.13 6.50 9.00 5.38 8.63 S. officinarum Cristalina 8.75 13.13 8.38 8.38 4.88 4.88 S. officinarum IS 76-514 6.13 9.88 4.00 4.38 5.00 4.75 S. officinarum Louisiana Striped 5.38 4.88 2.25 2.50 2.25 1.88

*DHT = height on day 14 subtracted from height on day 56

2LSD @ .05 = 7.97

N) 25

cultivars were subjected to 2,4-D treatment. Similar results occurred

when Mandalay and S£S 513 were treated with chlormequat; NAA also

reduced the growth rate of Mandalay. No other effects were indicated in

experiment two.

In an attempt to present the mean growth curve across experiments

one and two, the growth curves of each cultivar under each treatment of

the plant cane experiment are shown in Figures 1 through 14. The points

used to illustrate the growth curves are those mean height measurements

taken every two weeks for a period of eight weeks.

Figures 1 through 4 illustrate the growth of the S. officinarum.

These cultivars attained the least overall height of all cultivars

tested. Cultivars of S. spontaneum, Figures 11 through 14, were the

tallest overall. In general, all cultivars showed the greatest increase

in growth between day 28 and day 42.

Ratoon Results

The data of experiment three were analyzed separately to determine

the reactions of the cultivars as a "ratoon crop" to the tillering agents.

Table 10 is the analysis of variance for mean shoot number data of

the ratoon experiment. Significance was obtained for variety, treatment

and the variety by treatment interaction. Consequently, an LSD value was

calculated for the interaction means.

In Table 11, the variety by treatment interaction of the ratoon

experiment and the mean number of shoots produced by each cultivar as a

result of the effects of each treatment are presented. There were seven

cultivars in the ratoon experiment where no difference in mean shoot HEIGHT (CM) 22 23- 20 21 24- 25-i 14- 12- 13- 15- 16- 19- 17- 18 - - - - iue1 Teefc o fv ln got euaoso the on regulators growth plant five of effect The 1. Figure i"T- i - T i" i "r A U T M I ■UAL i j i i i egto the of height Cavengerie in the plant cane experiment. cane plant the in Cavengerie 1 A 1 K C M C U 14 '|— i""i " " i i — i' ■ i i Saaoharurr:officinarum ■ - i i i- DAYS 28 | i i i i i cultivar T 42 -I 1—T" I I I I 26 56 HEIGHT (CM) 20H H 2 22-f 23- 24H 25-1 26-j 15-! 10-1 17-1 19-1 27- 28- 29-i Figure 2. The effect of five plant growth regulators on the on regulators growth plant five of effect The 2. Figure ■r i r i CIlLOWtHJUAT i a n a p e i A U i i t t HAA tllH PIK M I I M PIK tllH BUALTA l.A-D l— i height of the the of height Cristalina in the plant cane experiment. cane plant the in Cristalina -

I—iiii 426 14 Saoaharurr.officinarvm DAYS -r—T— i— r- cultivar 42 i l— i - 27 r 56 r HEIGHT (CM) 20 ion 22 23-1 12-4 13H 16H 17H 1 2 4 56 42 28 14 0 Figure 3. The effect of five plant growth regulators on the on regulators growth plant five of effect The 3. Figure a-a-B A T L A M CIILOMIEIJUAT D E I A U T l U HAA height of the the of height IS 76-514 in the plant cane experiment. cane plant the in 76-514 IS x u i a Sacahxrum officinarum Sacahxrum DAYS cultivar 28 HEIGHT (CM) 26-j 23^ 2Pr- 22 20 19^ 17- 1G-: 16^ 15-: - - iue4 Teefc f iepat rwhrgltr o the on regulators growth plant five of effect The 4. Figure HM CU1CK UNIUATED Louisiana Striped in the plant cane experiment. cane plant the in Striped Louisiana the of height acaw, offLa-Lnarurr, Saocharwr, DAYS 26 cultivar 42 29 56 HEIGHT (CM) 5- .5 2 4 0- .0 0 3 - .5 2 3 - .0 5 4 5- .5 7 3 - .0 0 4 50.0 0 2 - .5 2 2 - .0 5 2 - .5 7 2 .0 5 3 15.0- . 0 - Figure 5. The effect of five plant growth regulators on the on regulators growth plant five of effect The 5. Figure * C M C D E T A U T H U A A H 2 , height of the the of height n h ln cn experiment. cane plant the in 4 D - acaw sinense Saccharw, DAYS 26 cultivar Katha cultivar 30 56 HEIGHT (CM) 20.0-j 22.5H 0- .0 5 2 .5H 7 2 30. OH 30. .5H 2 3 . 7 3 15. OH15. 17.5H .5H 2 4 .0 5 4 47.5H -\ 5 0 Figure 6. The effect of five plant growth regulators on the on regulators growth plant five of effect The 6. Figure (--f- I UNTUATSO THEPHON O H P E H ET A NA egt f the of height in the plant cane experiment. cane plant the in 428 14 k c e h c Saechavwn sinense Saechavwn DAY’S cultivar Chunnee cultivar 256 42

31

HEIGHT (CM) 20 21 24- 25- 27- 22 26- 28- 30- 23- 29- 32- 16- 14- 15- 18- 17- 19- - - - 0 Figure 7. The effect of five plant growth regulators on the on regulators growth plant five of effect The 7. Figure REATE CK EC H C ED T A E TR N U TA L A U E egto the of height n h ln cn experiment. cane plant the in Saooharum vobnstvm Saooharum DAYS 28 clia G 77-132 NG cultivar 42 32

56 HEIGHT (CM) 21 23 20 22 7A 15^ 25^ 17- 10- 19- 26-1 - iue . h fet f iepat rwhrgltr o the on regulators growth plant five of effect The 8. Figure l - B CK IC H C » I I A U I I U height of the the of height ntepat ae experiment. cane plant the in acau robustum Saccharum DAYS 20 clia G 77-160 NG cultivar 42 33 GG HEIGHT (CM) 5- .5 2 2 - .0 5 2 32.5^ - .0 5 3 - .5 7 3 5- .5 7 2 - .0 0 3 0 2 - .0 0 4 5.0- 1 17.5^ . 0 - iue . h feto iepat rwhrgltr o the on regulators growth plant five of effect The 9. Figure NUTD OIBCK UNTUATID HAA IIIALTA egt f the of height in the plant cane experiment. cane plant the in aoatr robustum Saoohartcri DAYS 26 clia G 77-76 NG cultivar 42 56 34 35

(-*-+ UtTMAlU CMCK

31 1,4-0 30 B -B -B I HALT*

29

23

27

2 6

2 6

24-

23-

22 -

21 -

20 -

19-

18-

17-

16-

15-

-i— i— i— i— t — i— i— i— !— j— i— ■— r ■ t — i— i— j— r — i— ]— i— i— i— i— i— r— i— i— '— |— i— i— t — i— i— i— i— i— t 14 26 42 56

DAYS

10. The effect of five plant growth regulators on the height of the Saooharum robustum cultivar NG 77-136 in the plant cane experiment. HEIGHT (CM) 100 110- 20 30- 40- 50- 60- 70- 80- 90- 10- - Figure 11. The effect of five plant growth regulators on the on regulators growth plant five of effect The 11. Figure CHECK D E T A M T M U U H 1UALTA 2,4-D Mandalay in the plant cane experiment. cane plant the in Mandalay the of height aoaiv spontaneum Saaohariev DAYS 26 256 42 cultivar 3 3 6 HEIGHT (CM) 20 25-: 30- 40' 35-: 45-^ 50- 55-: 1&: 60-: ID- 65^ - iue 2 Teefc f iepat rwhrgltr o the on regulators growth plant five of effect The 12. Figure UALTA T L A IU B - a - B M K * C M C D K A M T M I egto the of height ntepat ae experiment. cane plant the in aaau spontaneurr. Sacaharum DAYS 26 56 2 4 clia SS 513 SES cultivar 37 HEIGHT (CM) 20 25^ 30- 35^ 40- 50- 55-: 15^ 65-: 7(H - Figure 13. The effect of five plant growth regulators on the on regulators growth plant five of effect The 13. Figure UAK CUtaC UUMATKD height of the the of height in the plant cane experiment. cane plant the in acau spontaneum Saacharum DAYS 28 42 cultivar SES 577 SES cultivar 38 56 HEIGHT (CM) 5.0- 2 - .5 2 3 5.0- 3 0 2 2.5- 2 7.5- 2 0.0- 3 7.5- 3 40. OH 12.5- 10 15.0- 17.5- . . 0 0 - - iue1. h feto fv ln got rgltr n the on regulators growth plant five of effect The 14. Figure NRAE CHECKUNTREATED HAA ■UALTA egto the of height SES 205-A in the plant cane experiment. cane plant the in 205-A SES 14 aeair spontanevan Saeeharicr, DAYS 26 42 cultivar 56 3 9 Table 10. Analysis of variance for mean shoot number of the ratoon experiment.

SOURCE DF MEAN SQUARE

Cul 13 4911.35 ** Trt 5 806.00 ** Cul*Trt 65 145.13 ** Error 252 66.29

TOTAL 335

*** significant at the .01% level of probability Table 11. The variety by treatment interaction for mean number of shoots produced by plants of cultivars of different Saccharum species in the ratoon experiment^'

SPECIES CULTIVAR CHECK ETHEPH0N CHLORMEQUAT BUALTA 2,4-D NAA

S . spontaneum SES 513 26.50 58.75 56.50 59.75 60.25 56.25 S . spontaneum SES 577 20.75 42.50 35.50 38.25 42.25 43.00 S . spontaneum SES 205-A 18.50 57.75 41.75 27.00 30.75 44.50 S . spontaneum Mandalay 25.50 38.00 40.75 30.75 38.00 38.00 S. sinense Chunnee 26.00 38.00 34.00 23.50 29.50 26.50 S. sinense Katha 25.25 32.00 38.75 26.75 30.00 36.25 S. robustum NG 77-132 14.25 19.25 10.75 14.50 14.50 9.25 S . robustum NG 77-136 12.75 31-00 23.25 12.25 12.00 15.50 S . robustum NG 77-160 16.75 20.25 18.75 11.50 17.00 9.75 S . robustum NG 77-76 4.50 4.75 4.50 7.00 2.50 4.50 S. officinarum Cavengerie 11.50 18.00 6.75 11.50 22.75 11.00 S . officinarum Cristalina 12.00 13.50 18.50 10.00 9.75 10.00 S. officinarum IS 76-514 7.75 9.25 6.25 6.75 9.50 8.25 S. officinarum Louisiana Striped 12.50 9.50 8.00 10.25 9.25 8.25

OVERALL MEANS 16.75 28.04 24.57 20.70 23.43 22.93

1LSD @ .05 = 11.28 42

number occurred as a result of the treatments. These cultivars were:

Cristalina, IS 76-514, Cavengerie and Louisiana Striped of S. officinarum

and NG 77-132, NG 77-160 and NG 77-76 of S. robustum.

All treatments resulted in a higher mean shoot number than the check in the cultivars SES 513 and SES 577 of S. spontaneum. In the cultivar

Mandalay, the untreated plants produced fewer shoots than treated plants

in all the treatments except bualta which was not different from the

check.

Ethephon caused the highest mean number of shoots to be produced in

SES 205-A. The check plants produced fewer mean number of shoots than plants of all treatments except bualta which was not different. The effects of chlormequat were not different from NAA or 2,4-D, but these three treatments resulted in a higher mean shoot number than the check in this cultivar.

In Katha, chlormequat and NAA caused a higher number of shoots to be produced than the check. The effects of all other regulators were not different from the check.

Ethephon was the only treatment that caused an increase in mean shoot number over the check in Chunnee.

In NG 77-136, the ethephon and chlormequat treatments resulted in higher mean shoot numbers produced than the check. All other treatments showed no effect on this cultivar.

Ethephon and 2,4-D treated plants were higher in mean shoot number than those treated with chlormequat in Cavengerie, but neither was different from the check.

Table 12 indicates the increase in mean shoot number caused by the treatments over the check in each species. The data are presented as mean shoot number and percent increase over the check. Table 12. Growth regulator treatment effects on Sacchanan species as indicated by mean shoot number and percent increase over the check in the ratoon experiment.

INCREASE IN SHOOT NUMBER OVER THE CHECK1

MEAN NUMBER OF SPECIES SHOOTS OF CHECK ETHEPHON CHLORMEQUAT BUALTA 2,4-D NAA

S . spontaneum 22.81 26.44(115.9) 20.82( 91.3) 17.82C 78.1) 20.00(87.7) 22.63( 99.2) S. sinense 25.63 9.37( 36.6) 10.75( 41.9) -0.50( -2.0) 4.12(16.1) 5.75( 22.4) S . robustum 12.06 6.75( 56.0) 2.25( 18.7) -0.75( -7.0) -0.56(-5.0) -2.31(-20.2) S. officinarum 10.94 1.62( 14.8) -1.06(-10.7) -1.31(-12.0) 1.87(17.1) -1.56(-15.3)

OVERALL % INCREASE ( 55.8) ( 35.3) ( 14.3) ( 29.0) ( 21.5)

Percent increases in parenthesis

.t> 44

Saccharum spontaneum showed a high level of response to all growth regulators tested, as indicated by the high percent increase values. All growth regulators except bualta caused an increase in mean shoot number in S. sinense. The ethephon and chlormequat treatments resulted in a higher percent increase than 2,4-D and NAA.

Saccharum robustum responded positively to ethephon and chlormequat with all other treatments producing negative effects. In S. officinarum, ethephon and 2,4-D were the only growth regulators that caused an increase in shoot number. Three of four S. officinarum cultivars responded to ethephon in plant cane but all were non responsive to all growth regulators in the ratoon experiment. NG 77-76 and IS 76-514 did not respond to any chemical in either experiment.

Ethephon was the only growth regulator which resulted in an increase in shoot production across all species. Therefore, it had the highest percent increase when averaged over all species. Chlormequat also had a high percent increase when averaged over all species, however, S. officinarum responded negatively. Bualta decreased shoot formation in all species except S. spontaneum.

As in the plant cane experiments, height measurements were taken in the ratoon experiment every two weeks starting 2 weeks after planting.

The growth curves of each cultivar under each treatment of the ratoon experiment are plotted in Figures 15 through 28. The greatest increase in growth was between day 28 and day 42, as was experienced in the plant cane experiment. The increase in growth rate of the cultivars caused by the ethephon treatment was especially evident as shown in Figures 16 and

20 through 24. A reduction in growth was noted in NG 77-160, Figure 22, from treatment with NAA. This was due to the dying off of previously measured shoots. 45

32-1 UNTREATED CUEOt

HAA

30- ■UALTA

26--

26-1

24-

22 -

20 -

18^

16^

14-:

12-

10- •’ 1 I ^ r 14 26 42 56

DAYS

Figure 15. The effect of five plant growth regulators on the height of the Saacharum officinarum cultivar Cavengerie in the ratoon experiment. HEIGHT (CM) 21- 22 23- 24- 25- 26- 27- 28- 29- 30 SI- 32- 33- 34- 35-| - 0 Figure 16. The effect of five plant growth regulators on the on regulators growth plant five of effect The 16. Figure 't 1 CIILOMIflJUAT * - # - * A T L A M a - B - H I I— I— r— r CI1CCK D I M U 1 W M M CTHEMOH CTHEMOH D - 4 , 2 height of the the of height rsaia nte aon experiment. ratoon the in Cristalina 14 I -r 1 — -- 1 I — --- acav officinarum Saccharvm 1 -- 1 -- DAYS 1 -- 28 j ...... 2 4 cultivar -1— l ■ l— i— ’ i— r-— 46 6 5 HEIGHT (CM) 30- 24- 26- 28^ 32- 20 22 34-1 12- 14^ 18^ 16^ - - 0 Figure 17. The effect of five plant growth regulators on the on regulators growth plant five of effect The 17. Figure i 0-1 111 I | I I j | j l I 'H I I 'H CIILOMIEIJUAT CHECK U T A U tT U M M height of the the of height IS 76-514 in the ratoon experiment. ratoon the in 76-514 IS 14 1 acau officinarum Saccharum DAYS ■T— 1~ 26 1 i 42 cultivar -1— I I I— [• 56 47 HEIGHT (CM) 22 28^ 20 24- 26- 30- 32- 34- 36^ 30-1 16^ 10-: - - ’- - V 0 iue1. h efc ffv ln got rgltr n the on regulators growth plant five of effect The 18. Figure B-l ciiL HMTP t X ltC P UHTMATCP NAA e i u o height of the the of height Louisiana Striped in the ratoon experiment. ratoon the in Striped Louisiana ( t t a u j 14

acau officinarum Saccharum DAYS "• I- 8 2 —r-^— 42 cultivar

48 n r 56

HEIGHT (CM) 22.5H 25. OH 27.SH 30. OH 37.5H 42.5H 35. OH 47.5H 50.0 52.5H 55. (H 55. iue1. h fet f iepat rwhrgltr o the on regulators growth plant five of effect The 19. Figure U H CHICK ltD A U Im height of the the of height in the ratoon experiment. ratoon the in 140 acau sinense Saccharum DAYS 4228 cultivar Katha cultivar 56 49 HEIGHT (CM) 55^ 45-: 35^ 50 60- 30' 40- 65^ 7CH 25^ 20 - iue2. h feto fv ln got euaos n the on regulators growth plant five of effect The 20. Figure U H m i a o t t u K i i u height of the the of height in the ratoon experiment. ratoon the in aeau sinense Saceharum DAYS 28 cultivar Chunnee cultivar 42 50 56 HEIGHT (CM) . 40.oH 20. oH 22.5H 25. OH 27.5H 32.5H 30. OH 35. OH 37.5H 15. OH 42.5H 25H 12.5 o i 17.5H 45. OH . oH Figure 21. The effect of five plant growth regulators on the on regulators growth plant five of effect The 21. Figure 0 BUALTA H - I a CHICK U T iaU H U height of the the of height in the ratoon experiment. ratoon the in 14 Saoahanm robustum Saoahanm DAYS 26 42 cultivar NG 77-132 NG cultivar 56 51 HEIGHT (CM) 27- 30- 31-_ 33- 26^ ze- 29-; 32- 35- 36T 34- 37~. 38- ^ 3 40- 41- 42- 43-| 44- ] I T T *]" 14 0 iue 2 Teefc o iepat rwhrgltr o the on regulators growth plant five of effect The 22. Figure 1UALTA 0 - H - H 1 J— — T ' - f T l * e r u c D U A tlU U MAA egt f the of height in the ratoon experiment. ratoon the in »■I I I I '“ I " I I 1 I ‘I™ 1 I I I1 1 | I I I I" I f' “I I | I I I I-» ■I cehrm robustum Scteaharum DAYS 8 2 56 42 28 clia G 77-160 NG cultivar f ■ I I I I ■ » 52 \ HEIGHT (CM) 0 2 22.5 25.0- 5 . 7 2 30.0- 32.5 35.0' 37.5 42.5- 40.0 ,5 7 1 45.0' 47.5 50.0 52.5H . 0 - iue 3 Teefc o fv ln got rgltr o the on regulators growth plant five of effect The 23. Figure UATCD CHECK D C T A TU H U MAA egt f the of height n h rto experiment. ratoon the in aaau robustum Saaakarum DAYS 28 42 clia G 77-76 NG cultivar 56 53 HEIGHT (CM) 22. B^ 25.0- 27. 35.0- 32.5-1 37. 5^ 40.0- 15.0-: 17.5^ 42.5-1 Figure 24. The effect of five plant growth regulators on the on regulators growth plant five of effect The 24. Figure 0 NRAE CIIICE UNTREATED NAA ■UALTA height of the the of height in the ratoon experiment. ratoon the in aaau robustum Saoaharum DAYS 28 42 clia G 77-136 NG cultivar 56 54 HEIGHT (CM) 100^ 120-1 0 2 30- 40- 50- 60' 70 60 90 - 0 Figure 25. The effect of five plant growth regulators on the on regulators growth plant five of effect The 25. Figure HAA CHICK TUATID IM IUALTA Mandalay in the ratoon experiment. ratoon the in Mandalay height of the the of height aoau spontaneum Saoohapum DAYS 856 28 42 cultivar 55 HEIGHT (CM) 30- 50- 25- 5 5 60- 5 6 75- 00 70- 05- 90- 95-1 - iue 6 Te fet f iepat rwhrgltr n the on regulators growth plant five of effect The 26. Figure HME QltCK UHTMMED 2.4-D height of the the of height in the ratoon experiment. ratoon the in aoau spontaneum Saaoharum DAYS 26 42 cultivar SES 513 SES cultivar 56 56 HEIGHT (CM) 25- 30- 40 65- 20 35- 45- 55- 60- 50- 75- 00- 70- 85-J - Figure 27. The effect of five plant growth regulators on the on regulators growth plant five of effect The 27. Figure MAA CHECK IMTUATED ■UALTA 2,4-0 egto the of height nterto experiment. ratoon the in 14 Saccharum spontaneum Saccharum DAYS 26 42 clia SS 577 SES cultivar 57 56 HEIGHT (CU) 20 25- 30' 35- 15- 40 50 55- 60H - 0 Figure 28. The effect of five plant growth regulators on the on regulators growth plant five of effect The 28. Figure * e e n c D t T A u n u MAA ■UALTA height of the the of height SES 205-A in the ratoon experiment. ratoon the in 205-A SES Saocharum spontaneum Saocharum DAYS 842 28 cultivar 56 58 59

The untreated cultivars in the ratoon experiment were compared and ranked according to mean height as was done in the plant cane experiments.

The means were separated by a protected LSD test. Results are presented in Table 13.

Mandalay, SES 513 and SES 577 of S. spontaneum were the tallest of all cultivars tested. All cultivars of S. officinarum were shorter than all cultivars of S. sinense and S. spontaneum except SES 205-A from which they were not different.

The analysis of variance for difference in height (DHT) measurements is presented in Table 14. All sources of variation were significant, therefore LSD tests were appropriate.

The cultivars of S. sinense and S. spontaneum again exhibited a higher growth rate than cultivars of S. robustum and S. officinarum, as shown in Table 15.

No growth regulators affected the growth rates of Cristalina,

Louisiana Striped and NG 77-160. In Mandalay and SES 513, all growth regulators caused a decrease in growth rate.

Ethephon increased the growth rate over the check in IS 76-514,

Chunnee, NG 77-132, NG 77-76, NG 77-136 and SES 205-A. NAA and 2,4-D caused a reduction in the growth rates of Katha and Chunnee. The growth rate of Cavengerie was reduced by ethephon, chlormequat and 2,4-D. 2,4-D also reduced the growth rate of NG 77-132, NG 77-76 and SES 577.

Overall Discussion

Cultivars of S. spontaneum produced the highest mean number of shoots of all cultivars tested in both the plant cane and ratoon experiments. Saccbarum sinense cultivars produced a lower mean number of 60

Table 13. Mean heights for fourteen untreated cultivars of four Saccharins species in the ratoon experiment.

SPECIES CULTIVAR MEAN HEIGHT (cm)

S. spontaneum Mandalay 117.50 S . spontaneum SES 513 91,38 S . spontaneum SES 577 79.88 S . sinense Chunnee 59.63 S . sinense Katha 49.13 S. robustum NG 77-76 46.50 S. robustum NG 77-136 40.25 S. robustum NG 77-160 38.50 S. spontaneum SES 205-A 38.50 S. robustum NG 77-132 36.63 S. officinarum IS 76-514 33.88 S. officinarum Cristalina 32.50 S. officinarum Cavengerie 31.00 S. officinarum Louisiana Striped 30.88

LSD § .05 = 10.81 Table 14. Analysis of variance for difference in height measurements for the ratoon experiment.

SOURCE DF MEAN SQUARE

Cul 13 7891.02 ** Trt 5 900.46 ** Cul*Trt 65 107.45 ** Error 252 11.68

TOTAL 335

*** significant at the .01% level of probability Table 15. Difference in height (DHT) measurements* for variety by treatment interaction of Saccharum cultivars in the ratoon experiment

SPECIES CULTIVAR CHECK ETHEPHON CHLORMEQUAT BUALTA 2,4-D NAA

S . spontaneum Mandalay 73.00 55.25 57.13 66.63 53.38 32.38 S . spontaneum SES 513 62.63 52.13 47.63 44.63 48.75 54.25 S . spontaneum SES 577 52.63 56.63 48.38 50.63 28.38 52.13 S . spontaneum SES 205-A 22.50 30.00 25.13 25.88 20.00 23.63 S. sinense Katha 26.25 28.50 22.50 22.63 10.50 20.13 S. sinense Chunnee 23.00 28.75 19.25 26.63 13.15 14.88 S . robustum NG 77-132 12.00 22.13 10.88 7.38 5.25 7.63 S. robustum NG 77-160 6.00 10.25 5.13 1.38 3.75 2.25 S . robustum NG 77-76 14.50 27.00 15.50 14.50 8.00 9.88 S . robustum NG 77-136 11.00 21.75 7.62 7.50 6.88 7.38 S . officinarum Cavengerie 13.88 8.63 6.88 9.25 6.00 9.88 S . officinarum Cristalina 8.50 13.00 9.38 8.50 6.88 5.88 S. officinarum IS 76-514 6.13 11.63 3.00 3.88 5.13 5.50 S . officinarum Louisiana Striped 5.75 4.75 3.13 4.00 2.12 2.00

*DHT = height on day 14 subtracted from height on day 56

2LSD @ .05 = 4.74

C\ ro 6 3 shoots than those cultivars of S. spontanexm but were higher in mean shoot number than cultivars of both S. robustum and S. officinarum.

Most growth regulators tested caused the treated plants to produce more shoots than the check in the plant cane of most species. The lone exception was NAA which caused a negative response in S. sinense.

In the ratoon experiment, S. sinense treated with bualta produced a lower mean shoot number than its checks. Bualta, 2,4-D and NAA all caused a reduction in mean shoot number in S. robustum. S. of£icinarum responded negatively to chlormequat, bualta and NAA in the ratoon experiment.

The ethephon treatment was the most effective in promoting tiller formation over all species in all experiments. These results are comparable to those of Takahashi (24), Eastwood (7) and Wong-Chong (27), all of whom obtained a high level of tillering through the use of ethephon. Chlormequat treated plants were lower in mean shoot number than the ethephon treated plants in all experiments. However, chlormequat was more effective than bualta, 2,4-D and NAA in all experiments.

In addition to enhancing shoot production, the ethephon treatment increased the growth rate of the plants when averaged over all species in the plant cane experiments and was not different from the check in the ratoon experiment. The growth rate of plants treated with chlormequat and bualta was no different from the growth rate of the untreated plants in all experiments. Plants treated with 2,4-D and NAA indicated a slower rate of growth than the untreated plants in both the plant cane and ratoon experiments.

Certain cultivars of S. spontaneum in combination with ethephon application produced the highest mean shoot number and mean DHT 64

measurements of all possible cultivar by regulator combinations. A

significant increase in mean number of shoots over the check without

experiencing a decrease in the growth rate of the plants could also be

obtained through certain combinations of cultivars of S. spontaixexm or 5.

sinense with ethephon, chlormequat or bualta application. Similar

results were reported by Madrid and Rosario (17) who obtained a

significant increase in tiller formation with ethephon and bualta and Fao

(23) who stimulated tillering with ethephon and chlormequat.

Although experiments one and two were conducted under different

growing conditions, no evidence of a major differential cultivar response

to environment was indicated in the mean shoot number data. This suggest

that response to growth regulator treatment by the cultivars was

expressed independently of environmental influences. However, highly

significant differences in DHT data between experiments may be attributed

to environmental conditions.

There was little variation of growth rate among plants of

experiment one which were grown in large plastic pots of soil. The

greater degree of variation in response of the plants to treatment in

experiment two could have been caused by the stressful conditions created by the restricted root zone of the styrofoam trays.

It became apparent during the course of this study that those

species exhibiting a more vigorous growth habit were also exhibiting the

greatest degree of response to growth regulator treatment. A correlation

between the growth rates of each untreated species and their respective

mean shoot numbers averaged over all regulator treatments was calculated.

It can be seen in Table 16 that mean height was highly correlated to mean

shoot number in both the plant cane and ratoon experiments. 65

Table 16. Correlation coefficients showing the relationship of mean height of the untreated species to mean number of shoots of the treated species in the plant cane and ratoon experiments.

PLANT CANE EXPERIMENTS

mean height vs. mean number of shoots .99 ***

RATOON EXPERIMENT

mean height vs. mean number of shoots .97 **

*** significant at the .01% level of probability SUMMARY AND CONCLUSIONS

The main objective of this study was to identify those tillering

agents causing the greatest increase in shoot number without adversely

affecting the growth rate of the treated cultivars. It was also designed

to identify those basic genotypes of the genus Saccharum which exhibit a

high degree of response to certain growth regulators which have been proposed as tillering agents.

A series of three factorial experiments was conducted under

controlled conditions in the greenhouse. Four cultivars each of 5.

officinarum, S. robustum and S. spontaneum along with two cutlivars

representing S. sinense were selected to represent the spectrum of the

genus Saccharum. Five synthetic growth regulators and a check were used

as treatments. Shoot number and shoot height measurements were taken

every two weeks, beginning two weeks after planting, for a period of

eight weeks. From these data, increases in shoot production and growth

rate were calculated and compared by analysis of variance. Protected LSD tests were employed to compare treatment effects.

Plants treated with ethephon produced the highest number of shoots

and showed increased rate of growth as an average of all experiments.

The chlormequat and bualta treatments resulted in an increase in shoot number with no apparent effect on the rate of plant growth. NAA and

2,4-D increased shoot number, but plant vigor was decreased.

Cultivars of S. spontaneumf when treated with ethephon, produced the

highest mean shoot number and had the tallest plants. Certain

combinations of S. spontaneum or S. sinense cultivars with ethephon,

66 67 chlormequat or bualta resulted in a significant increase in shoot number over the check with no effect on the rate of plant growth.

It is now theoretically possible to produce commercial cultivars, via the breeding program, which would respond to ethephon used as a tillering agent. A series of backcrosses using cultivars of 5. spontaneum and commercial cultivars could be employed to acconq>lish this task. The cultivars resulting from this process should exhibit a high degree of response to ethephon by producing a higher number of shoots when treated. Actual testing of the response of these cultivars should perhaps be done in later ratoon crops when yields decrease.

This of course would depend upon how easily the trait of response is transferred from parent to offspring. A genetic study of this response characteristic is discussed in part two of this dissertation.

Because this study was conducted under greenhouse environment, these results may not be applicable under field conditions. Further research is needed to determine whether or not the results reported herein could be repeated under field conditions. PART II. BEHAVIOR OF TILLERING RESPONSE TO ETHEPHON TREATMENT IN TWO SEGRETATING POPULATIONS

68 INTRODUCTION

A genetic study of the response characteristic of the basic lines to the synthetic growth regulators proposed as tillering agents was conducted. This study followed the first part, in that the most effective tillering agent and genotypes representing the most responsive Saccharum species were used. This experiment was conducted to determine if the characteristic of response to tillering agents was under genetic control.

69 MATERIALS AND METHODS

A genetic study of response to ethephon used as a tillering agent

was conducted from March through June, 1985. Biparental crosses

utilizing the commercial cultivar CP 65-357 and two S. spontaneum parents

were made and the true seed were harvested and germinated at the USDA

Sugarcane Laboratory in Houma, Louisiana. Because of the availability

of a limited number of crosses containing S. spontaneum germplasm, the

Fj progenies of only two half-sib families were obtained (Table 1).

Single bud cuttings of the parental cultivar were germinated to

coincide with the growth of the seedlings germinated from true seed.

Ten plants of each parent were selected and transplanted, as were 150

seedlings of each biparental cross. This entire study was conducted in 1 33.75cm X 66.56cm styrofoam Todd planter trays . Each tray contained 2 eighteen 10cm X 10cm X 10cm cells filled with Jiffy-Mix Plus . After a period of one month, five plants of each parental cultivar and 100 plants

of each half-sib family were treated with ethephon. The remaining

parental plants and 50 plants of each half-sib family were untreated.

The ethephon was applied at a rate of 500 ppm using a back-pack type

sprayer. The treatment was applied to the foliage of the plants until

runoff occurred. Upon drying, the plants were placed in the greenhouse

along with the untreated plants in a completely randomized unreplicated

design.

*Speedling Incorporated, P. 0. Box 238, Sun City, FL 33586. 2 Jiffy Products of America, 250 Town Road, West Chicago, IL 60185.

70 Table 1. Parentage of the half-sib families utilized in the study of ethephon response.

CROSS // FEMALE PARENT MALE PARENT

84-3056 CP 65-357 X Mandalay 84-3057 CP 65-357 X SES 231 72

Biweekly height and total shoot number data were recorded on each plant for an eight week period. Shoot number data taken on day 56 of this experiment were used to compare treated and untreated plants of each parental cultivar and each half-sib family. An analysis of variance was conducted on these data to reveal the sources of variation causing significant differences. Height measurements on day 14 were subtracted from those on day 56 to obtain difference in height (DHT) measurements for each plant. These DHT data along with shoot number data were used to plot frequency distributions illustrating the effects of ethephon on the growth of the plants. RESULTS AND DISCUSSION

An analysis of variance was run on the shoot number data of the parental cultivars taken on day 56 of this experiment (Table 2).

Significance was obtained for treatment and parental variety sources of variation and the treatment by parental variety interaction.

Table 3 compares the means of treated vs. untreated plants within each parental cultivar. In all parental cultivars, the ethephon treated plants produced a higher mean number of shoots than the untreated plants.

An analysis of variance was also run on the shoot number data obtained from the progenies of each half-sib family on day 56 (Table 4).

There was no difference in mean shoot numbers produced by the half-sib families. The half-sib family by treatment interaction was also not significant. However, differences in mean shoot numbers attributed to the variation in treatment were significant. As can be seen in Table 5, the mean shoot number of plants treated with ethephon was higher than that of untreated plants in both half-sib families.

The response of the progenies of the half-sib families to ethephon treatment was the same as the response of each parental cultivar.

However, neither the three parents nor the two half-sib families differed in their response to ethephon, therefore, it was not possible to determine a great deal with regard to the genetics of this response.

Figure 1 compares the frequency distributions of treated and untreated seedlings, as a percent of total, of the cross CP 65-357 X

Mandalay. The plotted lines compare total shoot number on day 56 of the treated vs. untreated plants. Fifty-four percent of the untreated

73 74

Table 2. Analysis of variance for mean shoot number data of parental cultivars taken on day 56.

SOURCE DF MS

Treatment 1 58.8 Parental Cultivar 2 90.3 ** Trt*Par Cul 2 4.9 ** Error 24 0.733

CORR. TOTAL 29

*** significant at the .,01% level of probability

Table 3. Mean number of shoots produced by each parental cultivar comparing treated vs. untreated plants.

MEAN NUMBER OF PARENTAL CULTIVAR TREATMENT SHOOTS

CP 65-357 Ethephon 3.8 CP 65-357 Untreated 2.4 Mandalay Ethephon 7.8 Mandalay Untreated 5.0 SES 231 Ethephon 11.2 SES 231 Untreated 7.0

LSD @ .05 = 1.12 75

Table 4. Analysis of variance for mean shoot number data of each half-sib family taken on day 56.

SOURCE DF MEAN SQUARE

Half-sib Family 1 1.71 Treatment 1 361.93 ** HS Fam*Trt 1 20.91 Error 296 9.94

CORR. TOTAL 299

*** significant at the .01% level of probability

Table 5. Mean number of shoots produced by each half- sib family comparing treated vs. untreated plants.

MEAN NUMBER OF CROSS # TREATMENT SHOOTS

84-3056 Ethephon 7.33 84-3056 Untreated 5.56 84-3057 Ethephon 7.73 84-3057 Untreated 4.84

LSD @ .05 = 0.76 FREQUENCY AS PERCENT OF TOTAL 10 20 " 5 1 • - 5 2 ■ a iue1 Tefeunydsrbto, spreto oa, of total, of percent as distribution, frequency The 1. Figure " " h— t 2 3 3 2 t i —t —i —i —i —i h—i —i i— t— i— i— -hN— i— i— i— i— i— i— i— t— t— — h ensotnme aus fC 537wr 2. were 65-357 CP of A values number shoot mean The The mean shoot number values of Mandalay were 5.0 were of Mandalay values number shoot mean The untreated and 7.8 treated. 7.8 and untreated treated. 3.8 and untreated treated vs. untreated plants. compare untreated lines vs. treated Plotted number. shoot of function a as Mandalay X 65-357 CP croBS the of seedlings 4

5 e » 0 1 2 3 * 5 8 7 0 B 20 IB 10 17 18 15 1* 13 12 11 10 » e 7 t SHOOT NUMBER SHOOT

76

77 plants produced five shoots or less. Fifty-one percent of the treated plants produced at least eight shoots. CP 65-357 produced an average of

2. A ± 1.8 shoots untreated compared to 3.8 ± 0.7 shoots when treated.

Mandalay averaged 5.0 ± 0.5 shoots produced when untreated compared to an average of 7.8 ± 0.7 shoots under the influence of ethephon.

The frequency distributions comparing shoot numbers of treated vs. untreated plants of the cross CP 65-357 X SES 231 are plotted in Figure

2. Sixty-two percent of the untreated plants produced less than six shoots. Fifty-eight percent of the treated plants produced more than seven shoots. SES 231 produced an average of 7.0 ± 0.5 shoots when untreated and 11.2 ± 0.2 shoots when sprayed with ethephon.

Difference in height (DHT) measurements, as an indication of growth rate, were also used to plot the frequency distributions of plants as a

r percent of the total. Figures 3 and A illustrate the comparison of treated vs. untreated plants of the respective crosses based on DHT measurements.

Fifty-four percent of the untreated plants had DHT measurements less than 35.5 cm in the cross CP 65-357 X Mandalay (Figure 3). Of the treated plants, sixty percent had DHT measurements greater than 35.5 cm. The mean DHT measurement of CP 65-357 was 1A.3 cm untreated compared to 10.A cm under ethephon treatment. Mandalay had a mean DHT measurement of 60.1 cm untreated and 65.9 cm under treatment.

Figure A indicates fifty-two percent of the untreated plants had

DHT measurements less than 25.5 cm in the cross CP 65-357 X SES 231.

Fifty-seven percent of the treated plants had DHT measurements of 25.5 cm or greater. SES 231 had an average DHT measurement of A5.7 cm untreated and A8.6 cm when treated with ethephon. FREQUENCY AS PERCENT OF TOTAL 0 1 12' - 4 6- iue2 Tefeunydsrbto, spreto ttl of total, of percent as distribution, frequency The 2. Figure - - r^ 5 3 UNTREATED The mean 6hoot number values of CP 65-357 were 2,4 were 65-357 CP of values number 6hoot mean The The mean shoot number values of SES 231 were 7.0 231 were SES of values number shoot mean The untreated and 3.8 treated. 3.8 and untreated seedlings of the cross CP 65-357 X SES 231 as a as 231 SES X 65-357 CP cross the of seedlings treated vs. untreated plants. compare untreated lines vs. treated Plotted number. shoot of function nrae n 12 treated. 11.2 and untreated 7 9 TREATED 11 SHOOT NUMBER SHOOT 13 15 17 21 23

2519

78 79

2 0 -

1 0 -

5"

DHT UEASUREUENT(cm)

Figure 3. The frequency distribution, as percent of total, of seedlings of the cross CP 65-357 X Mandalay as a function of DHT measurements. Plotted lines compare treated vs. untreated plants.

The mean DHT measurements of CP 65-357 were 14.3 cm untreated and 10.4 treated.

The mean DHT measurements of Mandalay were 60.1 cm untreated and 65.9 cm treated. OF TOTAL 10 - ■ 5 iue4 Tefeunydsrbto, spreto oa, of total, of percent as distribution, frequency The 4. Figure 015 035 125 035 135 545 145 40-505 41-455 35-405 31-355 20-305 21-255 10-305 10-155 h enDTmaueet fSS21wr 57 cm 45.7 231 were SES of measurements DHT mean The untreated and 48.6 cm treated. cm 48.6 and untreated The mean DHT measurements of CP 65-357 were 14.3 cm 14.3 were 65-357 CP of measurements DHT mean The untreated and 10.4 cm treated. cm 10.4 and untreated function of DHT measurements. Plotted llneB compare llneB Plotted measurements. DHT of function a as 231 SES X 65-357 CP cross the of seedlings treated vs. untreated plants. untreated vs. treated \ DHT DHT UEASUREHEHT(an)

80

SUMMARY AND CONCLUSIONS

A genetic study was conducted from March through June, 1985. The purpose of this study was to determine if the characteristic of response to ethephon by progenies of S. spontaneum crosses was under genetic

control.

Progenies of two half-sib families involving S. spontaneum parents were utilized. Five plants of each parental cultivar along with 100 plants of each half-sib family were treated with ethephon. Five plants of each parental cultivar and 50 plants of each half-sib family were used as checks.

Biweekly height and total shoot number data were taken from each plant for a period of eight weeks. An analysis of variance was run on total shoot number data of each parental cultivar and progenies of each half-sib family. Shoot number and DHT data were used to plot frequency distributions comparing treated to untreated plants of each cross.

The response of the progenies of each half-sib family and their respective parental cultivars to ethephon was comparable to the response of the S. spontaneum cultivars tested in part one of this dissertation.

Total shoot number and growth rate was increased in the parental cultivars and their progenies through the use of ethephon as a tillering agent.

Unfortunately, differences in response of the half-sib families and their respective parents were not indicated in part two of this study.

However, the large differences in shoot number and growth rate among genotypes in response to ethephon in both plant and ratoon cane in part one suggest that this characteristic of response is under genetic control.

81 REFERENCES

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26. Weaver, R.J. 1972. Plant Growth Substances in Agriculture. W.H. Freeman & Co., San Francisco. 1:2-5.

27. Wong-Chong, J. and F.A. Martin. 1981. Greenhouse Studies on the Interaction of Genotype and Plant Growth Regulators with Regard to Early Tillering in Sugarcane. Sugar Agucar. 76(6):28.

28. Yang, P.C., F.W. Ho and C.C. Wei. 1980. Application of Plant Growth Regulators for Promoting Sprouting and Growth of Ratoon Cane. Taiwan Sugar. 27(4):131. APPENDIX Table 1. Effects of growth regulators on mean number of shoots produced by cultivars of different Saccharum species in experiment one

SPECIES CULTIVAR CHECK ETHEPHON CHLORMEQUAT BUALTA 2,4-D NAA

£. spontaneum SES 513 4.25 7.75 7.25 6.00 5.50 8.50 5. spontaneum SES 577 4.25 5.50 4.75 5.00 5.00 4.75 S . spontaneum SES 205-A 3.33 4.33 4.33 4.00 4.33 3.33 S . spontaneum Mandalay 3.50 4.50 4.50 4.50 3.75 4.75 S. sinense Chunnee 2.00 3.50 3.25 3.00 3.00 2.50 S. sinense Katha 2.25 3.25 2.25 2.50 2.25 1.75 S. robustum NG 77-132 1.75 3.25 3.25 2.00 1.75 2.00 5. robustum NG 77-136 1.00 1.00 1.00 1.00 1.00 1.50 S . robustum NG 77-160 1.75 3.00 2.25 2.25 2.50 1.75 S. robustum NG 77-76 1.00 1.00 1.00 1.00 1.00 1.00 S. officinarum Cavengerie 1.25 2.00 2.25 1.75 2.25 1.75 S . officinarum Cristalina 1.00 2.50 2.75 2.00 1.00 1.25 S, officinarum IS 76-514 1.75 2.25 1.25 1.50 1.00 1.00 S. officinarum Louisiana Striped 1.00 1.25 1.25 1.25 1.00 1.25

OVERALL MEANS 2.15 3.22 2.95 2.70 2.52 2.65

1LSD @ .05 = 1.02

00 Vjl Table 2. Effects of growth regulators on mean number of shoots produced by cultivars of different Saccharum species in experiment two*‘

SPECIES CULTIVAR CHECK ETHEPHON CHLORMEQUAT BUALTA 2,4-D NAA

S. spontaneum SES 513 4.25 6.00 5.75 5.25 6.25 4.75 S . spontaneum SES 577 3.75 6.00 6.00 4.75 4.25 3.75 S. spontaneum SES 205-A 3.75 7.00 6.00 4.75 4.75 4.00 S . spontaneum Mandalay 3.25 4.50 4.50 3.25 4.00 4.25 S . sinense Chunnee 3.25 5.25 4.50 4.00 3.50 3.25 S. sinense Katha 2.75 5.25 4.25 3.25 2.75 2.00 S . robustum NG 77-132 2.25 4.75 5.25 3.00 2.75 2.75 S . robustum NG 77-136 1.00 2.50 4.00 1.75 1.25 1.25 S . robustum NG 77-160 2.50 3.75 3.25 3.50 3.25 2.50 S. robustum NG 77-76 1.00 1.00 1.00 1.00 1.00 1.00 S . officinarum Cavengerie 1.25 3.75 2.50 2.00 3.00 2.00 S. officinarum Cristalina 1.25 2.75 3.00 2.00 1.25 1.50 S . officinarum IS 76-514 1.50 2.25 1.50 1.75 1.00 1.00 S. officinarum Louisiana Striped 1.00 2.75 1.50 1.50 1.75 1.00

OVERALL MEANS 2.34 4.11 3.79 2.58 2.91 2.50

*LSD @ .05 = 1.30

CD o% VITA

Keith Paul Bischoff was born July 12, 1955 in New Orleans,

Louisiana. He graduated from Archbishop Shaw High School in Marrero,

Louisiana in May, 1973. In August of 1973 he enrolled in Louisiana

State University and received a Bachelor of Science degree in Agronomy in December, 1976.

On August 12, 1977, he was married to the former Beleta M. Shambra of Gretna and is presently the father of one child - Kori Lynn.

He entered the Graduate School at Louisiana State University in

1978 while being employed as a Research Associate in the Sugar Station

Department.

Presently he is employed as Instructor in the Agronomy Department and is now a candidate for the degree of Doctor of Philosophy.

87 DOCTORAL EXAMINATION AND DISSERTATION REPORT

Candidate: K eith P. B is c h o ff

Major Field: Agronomy

Title of Dissertation: Response of Saccharum Species to Growth Regulators Used As Tillering Agents

Approved: c%L Major Professor and Chairman /Vs/Uxv Dean of the Graduate jSchooi

EXAMINING COMMITTEE:

(2

Date of Examination:

November 24, 1986