Effect of CCC, light intensity and nitrogen rate on cotton (Gossypium hirsutum L.)

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Title:
Effect of CCC, light intensity and nitrogen rate on cotton (Gossypium hirsutum L.)
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69 leaves : 28 cm.
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English
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Roland, Charles R., 1938-
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Cotton growing   ( lcsh )
Agronomy thesis Ph. D
Dissertations, Academic -- Agronomy -- UF
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bibliography   ( marcgt )
non-fiction   ( marcgt )

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Thesis:
Thesis--University of Florida, 1973.
Bibliography:
Includes bibliographical references (leaves 45-48).
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Typescript.
General Note:
Vita.
Statement of Responsibility:
by Charles R. Roland.

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Table of Contents
    Title Page
        Page i
    Acknowledgement
        Page ii
    Table of Contents
        Page iii
    List of Tables
        Page iv
        Page v
        Page vi
    List of Figures
        Page vii
    Abstract
        Page viii
        Page ix
    Introduction
        Page 1
        Page 2
        Page 3
    Literature review
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
    Materials and methods
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
    Results and discussion
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
    Summary
        Page 43
        Page 44
    Literature cited
        Page 45
        Page 46
        Page 47
        Page 48
    Appendix
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
        Page 68
    Biographical sketch
        Page 69
        Page 70
        Page 71
        Page 72
Full Text













EFFECT OF CCC, LIGHT
TINTENSITY AND NITROCTEN,
RATE ON COTrTOiJ (Gossy ur 1PJ.ir:SutuU I,.)











By

Charles R. Roland












A DISSERTATION PRESENTED TO THE GR..ADU.ATE CoTjLNfC 1 OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLM4ENT OF, THE REQUIRE1>IrNTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY














UNIVERSITY 02r FLGRIDA

1 '13












ACKNOWLEDGMENTS


The author wishes to express sincere appreciation to the following persons who helped make this dissertation possible:

Dr. E. B. Whitty who served as chairman of

graduate committee and assisted and advised through

the entire graduate program.

Mr. Shelby Baker, who constantly encouraged,

assisted, and advised during all phases of the research. He also provided numerous materials.

Drs. E. G. Rodgers; C. F. Douglas, V. N.

Schroder, and W. G. Blue, who served on the

supervisory committee, gave helpful advice and

constructively criticized the manuscript.

The Agronomy Department at the Coastal Plain Experiment Station, Tifton, Georgia, for providing facilities and supplies necessary in this study. American Cyanamid Company supported the research with financial assistance.

The writer is especially grateful to his family for

their encouragement and patience during the course of this study.






ii














TABLE OF CONTENTS


Page

ACKNOWLLDGELt S . .... . . ii

LIST OF TABLES . .. .. .. ... . . iv

LIST OF FIGURES ....... ................ vii

ABSTRACT.... ............. ............ viii.

INTRODUCTION .... ............... 1

LITERATURE REVIEW............... 4

MATERIALS AND METFODS ............. 13

Greenhouse Studi.es ........ ...... .. 13
Field Studies ..... ........... 15

RESULTS AND DISCUSSION .................. 18

Greenhouse Studies ............... 1
Field Studies ...... .......... 32

SUMMARY ........... ............... .43

Greenhouse Studies ........... .... 43
Field Studies. ................ 44

LITERATURE CITED................ 451

APPENDIX .... ............ .........49

BIOGRAPHICAL SKETCH ....... ........69











iii










LIST OF TABLES


Table P age

1 Effect of CCC on flowering rate of
cotton .................... .. . ... .. .. ...1

2 Effect of CCC on cotton boll set ..........20

3 Effect of CCC on cumulative number
of cotton bolls set per plant .. .... . . 23 4 Effect of CCC on cotton yield ...........24

5 Effect of CCC on cotton internode
length and plant height ...............26
6 Effect of CCC on cotton seed index
and germination ...................28

7 Effect of light intensity on flowering rate
of cotton ......................29

8 Effect of light intensity on cumulative
percent cotton boil set per plant ... ......30

9 Effect of light intensity on cumulative
number of cotton boils set per plant........31 10 Effect of light intensity on cotton yield.. .33

11 Effect of light intensity on cotton internode
length and plant height.. .............34

12 Effect of light intensity on number of days
from open cotton bloom to open boll ... ......35 13 Effect of light intensity on cotton lint
percent ...................... 5

14 Effect of CCC on cotton plant height .. ......37

15 Effect of CCC on cotton yiel& ... ........38

16 Effect of CCC on cotton quality ... ........39

17 Effect of nitrogen rate on flowering and
boll set of cotton.. ................41


iv









Table Page

18 Effect of nitrogen rate on cotton plant
height .......... . ............... 41

19 Effect of nitrogen rate on cotton yield. 42


Appendix Table

1 Effect of CCC on flowering rate of cotton. . 50

2 Effect of CCC on percent cotton flower
set per plant. .................... 51

3 Effect of CCC on cumulative percent
cotton boll set per plant ... .......... ...52

4 Effect of CCC on number of days from
open cotton bloom to open boll .... ...... 53

5 Effect of CCC on cotton lint percent .. . . 54

6 Effect of CCC on rate of cotton boll
development and root system weight... ..... 55

7 Effect of CCC on mineral content and
reducing sugars in cotton leaves ......... 56

8 Effect of light intensity on flowering
rate of cotton ........ ............. 57

9 Effect of light intensity on percent cotton
flower set per plant ....... ............ 58

10 Effect of light intensity on cotton boll
set ........... ..................... 59

11 Effect of light intensity on cotton seed
index and germination ....... .......... .60

12 Effect of CCC on flowering rate and
boll set of cotton ....... .............. 60

13 Effect of CCC on cotton fiber
elongation ..... ............. ..... 61

14 Effect of CCC on mineral content of
cotton leaves ................... .... ...2


v









Table P age

is Effect of CCC on cotton yield 63

16 Effect of CCC "~n cotton boll rot. 6 3

17 Effect of CCC an cotton defoliation.. 64

18 Effect of nitrogen rate on cotton fiber
elongation ...... ... ... ....... ... ... .... ... ... ... .... ... ... ........64

19 Effect of nitrogen rate on mineral content
of cotton leavos. ................65

20 Effect of nitrogen rate on cotton yield.. .. ...65

21 Effect of nitrogen rate on cotton quality.. 66

22 Effect of nitrogen rate on cotton boll rot. 67

23 Effect of nitroge~n rate on cotton
defoliation ... ..................67






























vi










LIST OF FIGURES


Figure P aI- e

1 Effect of CCC on total % cotton
boll set per plant .. ......... .... 22


Appendix Figure

1 Total rainfall per month for 1972,
showing departure from normal. ...... 68








































vii












Abstract of Dissertation Presented to the
Graduate Council of the University of Florida in
Partial Fulfillment of the Requirements
for the Degree of Doctor of Philosophy


EFFECT OF CCC, LIGHT INTENSITY AND NITROGEN
RATE ON COTTON (Gossypium hirsutum L.)



By

Charles R. Roland

June, 1973


Chairman: Dr. E. B. Whitty Major Department: AgronomyV


Greenhouse and field studies were conducted to determine the response of cotton (Gossypium hirsutum L.) to CCC,

light intensity and N rates.

Effects of CCC in greenhouse studies included: (1) increased % boll set and number of bolls set during the early flowering period but reduced boll production later in the season; (2) retarded plant height and internode length of mainstexus and fruiting branches; (3) decreased leaf content of X; (4) increased leaf content of N; (5) increased seed germination and (6) heavier seed. CCC had no statistical effect at the 5% level on leaf content of reducing sugars, number of days from open bloom to open boll and rate of boll development. Although there was no statistical difference viii








between root system weights, visual observation indicated that CCC may have increased the number of fibrous roots.

Effects of CCC in field studies included: (1) retarded plant height; (2) increased Ca and Mn content of l-eaves; (3) greater fiber strength; (4) reduced lint percentage and (5) lower yield. CCC had no effect on cotton yield at rates of 35 g (a.i.) per ha or less. CCC had no effect on flowering rate, number of bolls set for the 3 weeks immediately following chemical application, fiber elongation, boll size, fiber length,

fineness and uniformity.

Plants subjected to low light intensity in greenhouse studies: (1) fruited slower and with less efficiency than plants grown under normal light; (2) produced taller plants with longer mainstem and fruiting branch internodes; (3) required more days to develop an open boll from an open bloom, There were no treatment effects on lint %, seed index and germination percentage of seed from plants grown under the

3 levels of liqht intensity.

In field studies, N at 168 kg per ha increased flowering rate over the rate of 84 kg, but % flower set was greater under low N. Cotton yields were not different. High N increased leaf N content and plant height. Also, the plants were slightly more difficult to defoliate. Fiber quality characteristics, boll size and rate of fiber elongation were

not affected by N treatment.

Dry weather may have been responsible for no interaction

between CCC and N rates in this study.

ix















INTRODUCTION


Men have been producing, spinning, and weaving cotton

fiber since the dawn of civilization, and it has been a part of the history of every continent.

Eli Whitney's gin and the industrial revolution helped

establish the United States as a commercial power and spurred the growth of a new nation. Demands of mills in New England and a growing textile industry in this country caused growers of the Southeast to push southward and westward in search of new lands. They moved into Alabama and Tennessee, onward into Texas and even farther west. Today, the 18-state Cotton Belt stretches from the Carolinas to California and leads the world in cotton production, accounting for about

20% of the total supply.

Cotton exports in 1I970 were valued at nearly $492 million as contrasted with exports of less than $195 million for man-made fibers. Imports of synthetics exceeded exports by $11 million -- a deficit in trade value. Net earnings of badly needed foreign exchange amounted to $362 million for cotton

Cotton is the leading raw material of the textile and

apparel industries which in 1968 employed 2.3 million people


1









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with a payroll of $10.9 billion dollars -- second only to metals among manufacturing industries.

The American revenue from cotton arnd cottonseed at the farm level averages about $2.2 billion annually. This represents new, wealth, replenishing the economy each year to be multiplied many times over in the journey to consumer.

Some 300,000 cotton farms in the United States provide full employment for an estimated 500,000 operators and workers. Another 47,000 workers are employed during the peak seasons. Som~ie 40,000 are engagedl in glrmIing, 10,000 in warehousing and about 5,700 in cottornseed oil mills.

Numerous changes have taken place in cotton production during the last decade. increased mechanization, especially mechanical harvesting, has resulted in certain cultural changes. For example, higher plant populations increased internode length and height of the first boll from the ground. This is desirable for machine harvesting. Higher plant populations also increased plant height.

Almost all cultural changes during the last decade have

resulted in increased vegetative growth. These include better land preparation, greater fertilizer and lime use, improved rotations, better pes-t control and more vigorous varieties.

Cultural changes have been. desirable since more extensi-ve root systems reduce dry weather hazards and greater vegetative

growth usually increases yield potential. However, excessive vegetative growth may result in the fol]o- nq;








3

(1) increased insect problems; (2) delayed maturity; (3) boll rot; (4) lodging; (5) reduced yield; (6) poor defoliation;

(7) lower grades; (8) low harvesting efficiency.

In recent years, growth regulators have become increasingly important in agriculture. Growth regulators are being marketed for several crops, but none have been developed for cotton.

Cotton may shed 50% of its flowers, even if protected

from insects, when grown over the long growing season common in the southeastern United States.

Growth regulators offer a potential for limiting leaf expansion and increasing carbohydrate reserves, thereby improving flower retention and, consequently, increasing yields. Other potential benefits of growth regulators include more uniform maturity and a reduction in the adverse effects of excessive vegetative growth.

One of the growth regulators showing promise for use

on cotton is Cycocel (2-chloroethyl trimethylammonium chloride),

also known as CCC.

This investigation was designed to document the effects of CCC on individual components of the cotton plant during various developmental stages. Two factors intimately associated with vegetative growth and reproduction -- N fertilization and light intensity -- also were examined to determiri:e. possible interactions with CCC.








LITERATURE REVIEW


The plant growth regulating properties of 2-chloroethyl trimethylanmonium chloride (CCC) and related chemicals were reported first in 1960 by Tolbert (43) Cycocel is the trade name of Amrerican Cyanamid Company for its 1 pound per gallon formulation of CCC. For convenience, the term "CCC" is used throughout this paper when reference is made to the

above chemical.

The structural formula for CCC is Cl-CH2-CH2-N+

(CH3)3.CI- with a molecular weight of 158.1. Chlorrmequat has been established as the generic name by the British Standards Institute.

Mode of Action

In his earliest investigations, Tolbert (44) observed that CCC and gibberellic acid produced opposite growth effects in plants. CCC has been termed, consequently, as an "antigibberell..in", a term that in the biochemical sense implies specific competition between gibberellins and the growth retardant for 1 or several reaction sites in the plant. According to this definition, an antigibberellin should be a chemical analogue of gibberellic acid that can act as a substitute for the material in biochemical reactions However, according to Tolbert (44), no evidence exists that CCC is structurally related to gibberellic acid.


4







5

Kuraishi and Muir (19) conducted experiments with CCC and indoleacetic acid (IAA) on Alaska pea plants (Pisum sativum L.). Their findings suggest that retardation of stem growth by CCC was due to a lack of IAA and was independent of gibberelis. These investigators concluded that the growth retardant interacted directly with IAA to cause a decrease in the level of diffusible auxin.

Stoddart (36) suggested that CCC obstructs the metabolic system of plants because it interrupted nutrient assimilation and growth of Lolium temulentum L. He observed that stem elongation was arrested by CCC while photosynthesis proceeded at an appreciable rate. Thus, he concluded that free sugars normally utilized to sustain growth were polymerized, in the presence of the compound, to form storage carbohydrates.

Bristow (8), working with meristematic sections of

Pteris cretica L. leaves, found that CCC strongly inhibited growth of leaf sections but the effect was completely reversed by gibberellic acid.

Despite extensive experimental evidence that points to suppression of gibberellin biosynthesis as the probable mode of action, results of Khan and Tolbert (17) suggest that CCC may act through other routes as well. When either iAU or coumarin was applied to lettuce seeds (Lactuna sativa L.) in light, germination and root growth were inhibited. Application of CCC in light reversed these effects, while application of gibberellin did not. Sachs and Wohlers (34)








6

have also reported that CCC effects are not restricted to suppression of gibberellin biosynthesis. CCC inhibited cell division and enlargement of tobacco, chrysanthemum, and carrot tissue cultures in vitro. However, gibberellic

acid did not prevent the retardant-induced inhibition in vitro as it does with intact plants. Likewise, supplementary auxin did not reverse the inhibitions. Thus, the investigators concluded that the effect of CCC cannot be simply that of suppressing gibberellin or auxin synthesis. Azaleas

McDowell and Larson (26) subjected azalea cultivars

(Rhododendron obtusum L.) to short day length (Q hours) and natural day length (14 hours, 41 minutes) and found that CCC treatments applied to the Redwing variety caused earlil. flower bud initiation and a greater rate of floral development. Cathy and Stuart (9) noted that foliage of treated azalea

plants was much darker green than that of control plants. Stuart (37) and Gill (11) observed an increase in the number of flowers, although Gill reported blooming time may have been delayed.

Cotton

Thomas (40) treated Gossypiun hirsutum L. plants with foliar sprays of 25 to 100 ppm CCC. Applications were made at flowering and 2 weeks before and after flowering. Within 10 days of treatment, significantly shorter stems and greener foliage were observed. Fruiting branch








7

elongation was suppressed so that bolls on adjacent nodes almost touched. Rate of flowering wvas inhibited and seedcotton production reduced.

Thomas (41) found that 18 to 140 g (a.i.) per ha CCC

applied at peak of flowering, reduced plant height. Yields were only slightly decreased and he suggested that chemical retardants could potentially minimize undesirable late season growth and fruiting of cotton.

Hamawi (14) applied single and repeated foliar sprays of CCC to Gossypium barbadense L. at rates of 5, 10, 25, 50 and 75 ppm. Earlier and more uniform flowering were observed in treated plants. Yields were increased at dosages of 25 and 50 ppm, decreased at 75 ppm and not affected at 5 ppm.

Gutierrez (12) found that cotton yields were increased when treated 70 days after emergence at the rate of 10 g (a.i.) per ha. CCC increased boll frequency, but had no effect on the number of fruiting branches. Thus, the main treatment effect appears to be increased boll retention which gives higher yield. No effect was noted on plant height.

Singh (35) in 1970 established 93 demonstration plots in which 1 acre plots were divided into 4 equal blocks.

Two blocks were sprayed with water arid the other 2 with 32 ml of 50% CCC per acre, 75-90 days from planting. Average yield increase of all treated plots was 15%. Singh








8

concluded that- yield increases were due to increased root systems in relation to shoot growth, resulting in greener leaves because of higher nutrient and water content; as a consequence, plants remained physiologically active longer and produced heavier bolls.

Gausman et a'. (10) reported that leaves of cotton sprayed with CCC at the rate of 100 g (a.i.) per ha were 40 thicker and had 20% greater surface area. CCC-treated leaves had a 3-fold increase in number of intercellular spaces within mesophylls. Spectrophotometric measurements of spectra of individual leaves over the wavelength interval 500-2500 nm revealed a 5% increase in reflectance and a 6% decrease in transmittance for treated compared to untreated leaves.

Bhatt snd Seshadrinathan (4) found that CCC enlarged

the spongy parenchyma more than the palisade in G. hirsutum L. varieties but reversely affected G. barbadense L. varieties. CCC also increased thickness of the upper epidermis. The research workers suggested that CCC may induce tolerance to

drought by developing wider and stronger palisade and thicker leaves.

Poinsettia

Lindstrom and Tolbert (21) in 1960 observed that CCC

altered growth characteristics of poinsettia (Euuherbia pulcherrima Wo) but did not change the number of leaves or number of days toc flowering. CCC treated plants were shorter









9

with darker green and thicker leaves. Later, Besemer (3) found that poinsettia bract diameters were reduced by CCC.

Larson and McIntyre (20) reported that cuttings from CCC treated stock plants resulted 4n excellent quality plants. Stock plants were treated with either a foliar spray or a soil drench at 2,950 ppm and no further application was made to cuttings.
Tomatoes

In 1960, Wittner and Tolbert (45) described tomatoes

(Lycopersicon esculentum M.) treated with foliar application of CCC as having shorter internodes, darker green foliage and more leaf chlorophyll. Tiessen (42) reported the same changes in plant characteristics when the product was

applied as a soil drench.

Abdalla and Verker (1) investigated the effect of CCC on tomatoes at 2 temperature regimes: 350 C day and 250 C night compared to 220 C day and 180 C night. CCC retarded stem growth at both temperatures but plants at high temperature resumed normal growth rate sooner. Applied to soil at start of flowering, CCC reduced flower shed and increased fruit set and development at the high temperatures. However, at the lower temperature levels, there were no clear effects of CCC. The researchers also

found that plants treated with CCC accumulated a higher tissue N level.








10

Cereal Grains

Many investigators including Linser et al. (23), Mayr et al. (25), Primost (31), and Tolbert (43) have reported that the enhanced stem strength and dwarfed growth induced by CCC in wheat plants (Triticum vulgare V.) prevented or suppressed lodging.

Greater tolerance to such stress conditions as drought and soil salinity has been reported by Miyamoto (27). Adler (2) showed that CCC increased both total root growth

and number of wheat kernels per head.

Bokhari and Youngner (6) found that barley (Hordeum vulgare L.) responded more to CCC soil drench than to foliar sprays and attributed the yield increase to more head-producing tillers and heavier kernels. These same investigators (7) later determined by microscopic

examinations that tiller primordia were present in most leaf primordia axils of young untreated plants. They concluded that growth of these primordia was promoted by CCC.

Johnson and Schafer (16) observed that CCC caused wheat plants to remain sturdy and non-etiolated in thick plantings for a longer time than untreated plants.

Ota, et al. (29) reported that CCC retarded stem

elongation in rice. Later, these same investigators (30) observed that rice (Oryza sativa L.) responded to treatment

only when sown thickly. Tolbert (44) found that CCC-treated










oats developed shorter int-nodes. LiLnser and Kuhn (22) noted a similar effect on rye (Secale cereals L .), WOh.Lcf' was also resistant to lodging.

Kuhn (18) otbserv;ec improved seedling vigor and plant

development in plants grown froin treated seed. I~e concluded that opt-iimn rates of foliar sj~rays on cer-eal grains varied accordinMg tzo .-:n V4ronzental conditions and plant variety. Mis ce--l nons Responses

Halevy and Kessler (13) sho-,eld that CCC increased tolerance to stress condCitions such as drought, :t rost ad soil alkali-ity of various plants treated with CCC, Greater frcst resistance in cabbage (BLsiacl-eracea L.) was aicrecor-ded by Marth (24)

Read a.:nd Hoysler (33) dipped barnaceous cutLtings in a CCC sol.u l-ion and observed a marked. supression of dntitious Iroot production.

Hore and Bose (15) treatLed numerous species of fElowering shrubs and observed increased flowering, with mnore th~e.n a 100% increase in Clerodendron 2macrcsphon L. IncreaseJ flower an.-d fru-it production of lemons was reported 3by MUonselise and cow-,,orkers ( 2 8).

Ray ard Schroder (32) found -that sunflow.,er (Rlelianthus

tiuberosus L.) plants grown from seed soaked In a CCC solution were shorter than. control plants. However, th,1-eraarns concluded that soil. au,-.plicati,;on.- were much more effective thar seed traretperlhaps bec--rauso much larger q-,nL Le oE- the chemical were absorbed b;Z the rootL-s.








12

Bobak (5) working with Vicia faba L., noted that certain concentrations of CCC caused such phenomena as stickiness and disturbance of chromosome matrix besides a decrease of cell division. Tanaka (39) and co-workers concluded that CCC stimulated activity of partially purified choline kinase, had no effect upon activity of plant phosphorylcholine nor upon ATPase from wheat roots or leaves.

Tahori et al. (38) tested CCC for effects of feeding by cotton leafworms on beans. After 13 days, 72% of the control plants were destroyed compared to only 13% of the

plants sprayed with CCC.








MATERIALS AND METHODS

I. Greenhouse Studies

The studies were conducted at the Coastal Plain Ex'peciment Station, Tifton, Georgia. One of the experiments was designed

to document effects of various raLes of CCC on cotton growth and development under 3 levels of light intensity. A 3x8 factorial with 6 replications was arranged in a completely randomized design.

The greenhouse was divided into 3 equal sections with light intensities serving as whole plots and established as follows:

A. High Light Intensity To increase light reflec-tion throughout the cotton canopy, pots were wrapped

with aluminum foil and placed on the greenhouse floor, which was covered with the same material.

Aluminum foil partitions surrounded the high light

intensity plot. Six fluorescent daylight bulbs

(2.4 m long) were suspended above the plants and controlled with a time clock to come on at 6 a.m.

and go off at 8 p.m. Light meter measurements at various times during the experiment indicated the

light intensity here to be 120% of normal.

B. Low Light Intensity Light intensity was

reduced to approximately 50% of normal by

suspending wooden frames covered with polypropylene

shade cloth above the plants.


13








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C. Normal Light Intensit' The normal light treatment was sunlight filtered by greenhouse

covered by a thin coat of latex paint.

CCC rates served as sub-plots and were as follows: 0, 9, 18, 35, 70, 140, 280 and 560 g (a.i.) per ha.

A Tifton sandy loam soil with pH 5.8 was mixed with

peat moss in a ratio of 3 to 1 by volume. The soil mixture contained 1121 kg per ha each of lime and 5-10-15 fertilizer, In order to assure adequate blending, the soil, peat, lime and fertilizer were mixed together in a concrete mixer.

Four seed (cv. Coker 310) per pot were planted in

4-gallon plastic containers on April 4, 1972. Later each pot was thinned to 1 plant. CCC was applied in 94 liters of diluted solution per ha on May 31, 1972, 57 days after planting, when plants were about 76 cm tall (approximately first flower).

Flowers were tagged and counted daily for 7 weeks

for calculation of weekly flowering rate, cumulative flowers at selected dates and boll set. Number of days from open flower to open boll was determined.

Plant height was measured 30 days after CCC treatment

and at maturity. Average internode length for both mainstem and fruiting branches was recorded 30 days after treatment. Mainstem internode length was determined by averaging the second through the fifth internodes below the terminal bud. Fruiting branch internodes were measured by averaging 3










internodes on the second, third and fourth fruiting branch from the terminal bud.

Yield was recorded as nunter of bolls and g of

seedcotton per plant. The seedcotton was ginned on a small portable roller -in and seed index calculated as g per 100 seed. The effect on germination was tested by placing 100 seed, divided into 2 replicates, in a seed germination chamber for 7 days. Temperatures automatically rotated to 200 C for 16 hours and 300 C for 8 hours.

In order to further evaluate the effects of CCC on

cotton, another experiment was initiated in a similar manner to that previously described except light intensity variables were omitted. The test was arranged in a completely randomized design and replicated 6 times.

Rate of boll development was determined by oven-drying

and weighing bolls removed 10, 20 and 30 days after flowering. Young mature leaves were selected 44 days after CCC treatment. These were air-dried and ground in a Wiley mill. Plant samples were analyzed for reducing sugars and mineral element content. Root weights were recorded after washing, screening, and oven-drying.

II. Field Studies

A field study was designed to observe the effects of

CCC on cotton grown at different levels of N fertilization. A 2x6 factorial experiment was arranged in a randomized








16

complete block design with 4 replications. Nitrogen rates were 84 and 168 kg per ha. CCC was applied at 0, 9, 9 (3 times, 10 days apart), 2.8, 35 and 280 g (a.i.) per ha.

The Coker 310 cv. was planted May 10, 1972, on a

Tifton sandy loam soil (p.H 5.8) at the Coastal Plain Experiment Station, Tifton, Georgia. Each plot contained 4 rows (96.5 cm apart and 14 m long). Observations were made on the 2 center rows. The entire area received 448 kg per ha of 7-14--21 fertilizer prior to planting and 560 g per ha of B on the foliage at early squaring. Nitrogen was applied by hand on June 6, 1972. Weed control consisted of 560 g trifluralin incorporated before planting, 168 g fluometuron preemerge at planting and 3 mechanical cultivations.

CCC was applied with a high clearance sprayer as a foliar spray in a 188 liters per ha diluted solution on July 11, 1972, (62 days after planting) at approximately

1 week after first bloom.

Flowers were tagged and counted daily except Saturdays and Sundays on a 3.05-m row segment for 3 weeks immediately following CCC application. Flowering rate, % boll set and cumulative boll set were observed in this 3-week period.

Average plant height was calculated at 15 and 30 days after CCC treatment and also at maturity. Plant analysis of youngest mature leaves for mineral element content was made at 30 days from treatment on August 10, 1972.

Flowers were tagged on July 21, 1972, (10 days after CCC treatment) Bolls were removed at 5, 10, 15, and








17

20 days after tagging and fiber length Lmeasured. To d et erm ie fiber length, a lock from, a. boll was placed in a beaker of boiling water (for boils 20 days old, 2.5% HCl was used) to dissolve simple sugars and allow the seed with attached fiber to float free. The seed were -then floated out on the convex side of a watch glass, the fiber made to stream out with a jet of water and length measured with a centimeter rule. All measurements were made from the rounded chalaza end of the immature seed. Fiber of 8 to 10 seed per boll from

3 different boils was measured and averaged for each determination.

Other measurements included the effect of CCC and N rates on boll rot, % defoliation and yield. Also, samples of 50 boils per plot were hand picked, ginned and used to determine boil size, lint %, fiber length, strength and micronaire.









RESULTS AND DISCUSSION

Effects of CCC were visible in all studies within

2 weeks after treatment. CCC treated plants had less height and internode length. Leaves were thicker and greener on treated plants. Bolls were spaced so close they almost touched each other where highest rates of CCC were used.

Greenhouse Studies

CCC

Flowering rate and boll set were recorded daily for

7 weeks after CCC application. Flowering rate reached a peak during the fourth week of flowering (Appendix Table 1). CCC did not significantly affect flowering rate until after completion of the first 4 weeks of flowering (Table 1) Cumulative flowering rate was reduced after the fifth week by CCC rates of 35 g (a.i.) per ha and greater. The reduction in flowering rate was due to an apparent lack of new fruiting bud development. CCC was so effective that no new vegetative and/or fruiting branches formed; consequently, fruiting ceased.

CCC treatment caused no significant differences in percentage of cotton flowers set during the initial 4 weeks of flowering (Appendix Table 2). However, 140 g (a.i.) per ha, or more, of CCC reduced percentage of flowers set during the fifth and sixth weeks. There were no differences


18










19


Table 1. Effect of CCC on flowering rate of cottonl.


CCC rate Weeks frci-,- first flo-i7er

g (z'. CUM / Ulative- f 10WErs/pia-zt

C 0.6 3.8 9.3 15.8 22.4a 27.8a 29.3a

9 0.6 '3. 9 9.0 15.2 2 ".I ab 2 5. 9abc 2Y7. 2abc

18 0.5 cd2-1.7 .9.4 15.9 2L.6ab 26.9ab 2 8. 8 ab'

35 0 .IS 3.9 9.2. 14.6 20. 7abc 24.1 bc 25-i. 3 bc

70 0.6 4.0 9.2 14.8 20.0 bc 23.7 bc 214.7

140o 0.7 4.2 9.6 14.7 19.9 bc 23.8 bc 24.9 c

230 0.8 4.3 9.4 15.6 20.4abc 24.2 bc 24.7 c

560 0.7 4.4 9.7 14 .2 18. 8 c22.7 c 24 .0 c,



1 T're,,i merts rnot f'ol,'o- ad by the same letter di-ffer significanLly ait the- 5% level accordTing to Duncan 's Multiple Palicge Test. T her arc ---.inf cn di fferu nces betw,,,ee:n t -atments
in coma~ns h~at. have .7.o letters.









20
1
Table 2. Effect of CCC on cotton boll set.



CCC rate Weeks from first flower
1 2 3 4 5 6 7
g (a.i.)/ha bolls/plant/week

0 0.61 2.78 2.17 2.06a 2.39a 1.50a 0.28

9 0,56 3.11 1.94 1.72a 2.33a 1.72a 0.11

18 0.39 2.94 2.39 1.78a 2.00ab 1.28ab 0.11

35 0.78 2.89 2.17 1.67a 1.61ab 1.17ab 0,0

70 0.56 3.11 2.61 1.72a 1.44 b 1.17ab 0.0

140 0.67 3.39 2.72 1.28ab 0.56 c 0.89abc 0.50

280 0.78 3.33 2.94 1.56ab 0.67 c 0.39 bc 0.11

560 0.72 3.67 2.72 0.83 b 0.56 c 0.17 c 0.0







1 Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple Range Test. There are no significant differences between treatments in columns that have no letters.










in cumulative percentalir flower set for weeks 1-4 or weeks 1-7 (Appendix Table 3). Even so, there appears to be a trend with CCC increasihcg flower set during the first month of flowering (Figure 1).

Boll set was redund by the 560 g (a.i.) per ha of

CCC during the fourth Wek of flowering (Table 2). Rates of 70 g (a.i.) and greater increased boll set the fifth week, as did rates 280 g (a.i.) and greater the sixth week of flowering. The redoction in number of bolls set in late season from the higher rates of CCC is due both to a reduction in flowering arnd % flower set. Actually, CCC treatment increased th, number of bolls set per plant during the first 3 weeks of flowering (Table 3). However, total boll set per plaui for the entire growing season was reduced when CCC rontes were 140 g (a.i.) or greater per ha. The 560 g rato reduced boll set by about 26%.

Total boll set per plant can be used as a indicator of yield (Table 4). IHowever, fruiting period under field conditions is quite va [able due to influence of genetic, environmental and insew, factors. For example, an early freeze or dry condition; in September can completely stop fruiting, Therefore, wreful evaluation of cumulative boll set at various inlrvals is encouraged rather than total boll set foy the entire season.








22 60 59.

58 57 56 55

54 53

52



o
,o. 50

49 48 47

46 45



0 9 18 35 70 140 280 560

CCC rate, g (a.i.) /ha Figure 1. Effect of CCC on total % cotton boll set per plant

during first 4 weeks of flowering.









23

Table 3. Effect of CCC on cumulative number of cotton bolls set per plant.1


CCC rate Weeks from first flower
1 1-2 1-3 1-4 1-5 1-6 1-7
g (a.i.)/ha cumulative bolls set/plant

0 0.6 3.4 5.6 c 7.6 10.0 11.5a 11.8a

9 0.6 3.7 5.6 c 7.3 9.7 11.4a 11.5ab

18 0.4 3.3 5.2 c 7.5 9.5 10.8ab 10.9abc

35 0.8 3.7 5.8 bc 7.5 9.1 10.3ab 10.3abc

70 0.6 3.7 6.3abc 8.0 9.4 10.6ab 10.6abc

140 0.7 4.1 6.8ab 8.1 8.6 9.5 bc 9.7 cd

280 0.8 4.1 7.1a 8.6 9.3 9.7 bc 9.8 cd

560 0.7 4.4 7.1a 7.9 8.5 8.7 c 8.7 d


1
1 Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple Range Test. There are no significant differences between treatments in columns that have no letters.








24

Table 4. Effect of CCC on cotton yield.1

CCC rate Bolls/plant Seedcotton/plant
g (a.i.)/ha no. g

0 ll.8a 48.5

9 11.5ab 54.6

18 10.9abc 50.0

35 10.3 bc 49.2

70 10.6abc 54.4

140 9.7 cd 49.1

280 9.8 cd 53.6

560 8.7 d 49.1



1 Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple Range Test. There are no significant differences between treatments in column that has no letters.








25

There were no statistical differences between weights of seedcotton due to treatments (Table 4). Weights were influenced by severe boll rot which occurred during boll opening. The rot was probably due to high humidity in the

greenhouse.

Plant height and internode length were affected by

CCC (Table 5). Plants sprayed with rates of 18 g (a.i.) or higher per ha had shorter mainstem and fruiting branch internodes. Plant height 30 days after: treatment and at maturity was significantly less in all plants treated with

CCC. Heights ranged from 9 to 33% less than checks, depending on chemical rate.

CCC had no effect on time from open bloom to open

boll, cotton lint %, or rate of boll development (Appendix Tables 4, 5, and 6). Visual observations of washed roots suggested that CCC treatment may have increased number of fibrous roots, although root weights did not bear out this

observation (Appendix Table 6).

CCC treatment affected mineral content but had no

effect on reducing sugars (Appendix Table 7). Amount of reducing sugars is one indicator of photosynthetic activity and/or respiration. Potassium content of leaves decreased when CCC was applied at 280 g (a.i.) or greater per ha. CCC at 560 g increased the percentage of N in the leaves. There were no differences in leaf content of other mineral elements.














-P kl 4-1
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27

Data in Table 6 show that seed quality was improved by CCC. Seed index was greater at all levels except

the 18 g rate of CCC. Germination of seed from plants treated with CCC increased when treatment rates were 280 g and greater.

Light Intensity

Light intensity did not influence the effects of CCC measured in these studies. However, plants responded to different light treatments independently.

Low light intensity reduced flowering over the entire 7-week fruiting period (Table 7). Plants grown under normal light had a higher flowering rate the first 4 weeks. After the fourth week, there was no difference in cumulative number of flowers between high and normal light intensity. However, both high and normal light resulted in about 20% more total flowers than plants receiving low light. In addition to this lower flowering rate, the cumulative percentage of flowers set during weeks 1-4 was lower (Table 8). There were no significant differences in flower set at different light intensities over the 7-week flowering period. Plants under normal light set the largest number of bolls during weeks 1-4, followed by high light intensity plants and those receiving low light intensity set the lowest number (Table 9). Total boll set at the end of 7 weeks was significantly lower in low light intensity plots with no difference between boll set in high an.d. normal light.









28

Table 6. Effect of CCC on cotton seed index and germination.1


CCC rate Seed index Germination
g (a.i.)/ha g/100 seed %

0 11.0 c 85.0 cd

9 11.9ab 85.5 bcd

18 11.4 bc 83.6 d

35 11.9ab 85.6 bcd

70 12.2a 86~.2 bcd

140 12.2a 88.6abc

280 12.5a 90.7a

560 12.6a 89.7ab


1
Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple Range Test.











29






U') Co 0

0\0
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30


Table 8. Effect of light intensity on cumulative percent cotton boll set per plant.1 Weeks frora first flower
Light intensity 1-4 1-7

High 53.7a 39.2

IL Ow. 48.7 b 41.5

Normal 55.9a 42.5



1 Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple Range Test. There are no significant differences between treatments in column without letters.



















C 1 1
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rH 4j
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4-4 Ln
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0 m co C:) co
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32

Normal light intensity resulted in the highest yield of seedcotton per plant, high light intensity being intermediate (Table 10).

LightI effects on plant height and internode length

appear in Table 11. Low light intensity increased mnainstLem internode length by 22% and fruiting branch internodes were about 33% longer than those grown under normal light intensity. Low light caused taller plants than high or normal light.

Table 12 shows that reduced light increased the number of days from open bloom to open boll. While the difference was only 2 days, it was highly significant.

Light appeared to have little effect on lint-seed

measurements. Low light intensity resulted in plants with lower cotton lint percentage (Table 13) but there was no difference between normal and high light.

There was no difference in seed index or germination percentage of seed from plants grown under the 3 levels of light intensity (Appendix Table 11).

Field Studies

Excessive vegetative growth often occurs in Georgia when cotton is fertilized with high N rates, However, this was not the case in 1972, because of low rainfall (Appendix Figure 1) Moisture was deficient most of the growing season and especially during the fruiting period. For this reason, data from greenhouse studies probably describe more accurately the responses of cotton to CCC.









33



TabiLle 10. Efeto-f light intensity on cotton yield.1

-!it intens iyBolls S eedcotton
no./plant g/plant

Hgh 10.8a 50.3 b

Low 9.3 b 43.9 c

Norma l1. la 59.Oa




'reatments not followed by the same letter differ 5' iific4nty at the 5% level according to Duriczm's Iutipie Range Test.











34






C)
.H
(D Q'
r-I lc c"I m (Na 0%0
rl I -q l -q 11-1
4j U

r-4 4-J
04
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ro
9

U
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Q)
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4-J
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0 r
44 4-) iz: Q
4-1 .-ql
ki U) 0
41 41
(D


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35

Table 12. Effect of light intensity on nunter of days from open cotton bloom to open boll.

Light intensity Open bloom to open boll
days

High 52.2 b

Low 54.1a

Normal 51.9 b



1 Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple
Range Test.










Table 13. Effect of light intensity on cotton lint percent.


Light intensity Lint
%

High 40. la

Low 38.5 b

Normal 40.4a



1 Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple Range Test.








36

CCC

CCC had only a limited influence on plant height (Table 14). Only the highest rate resulted in less height; however, the lower height persisted throughout the growing season. This contrasted to a height retardation threshold of 18 g per

ha in greenhouse tests. Perhaps this was a function of moisture.

CCC had no effect on flowering rate, flower set or

boll set for the 3-week period immediately following chemical

application (Appendix Table 12).

CCC treatment did not influence the rate of fiber elongation as determined by fiber length measurements of 10-, 15-, and 20-day-old bolls (Appendix Table 13). Since cotton

fibers reach maximum length in about 18-20 days after flowers open, older bolls were not measured.

Leaf content of Ca and Mn increased with higher rates of CCC (Appendix Table 14). Rates of 18 g (a.i.) per ha and greater resulted in significantly higher amounts of these elements. Other minerals were not affected by treatment.

CCC rates ranging from 0 to 35 g (a.i.) per ha had no effects on yield (Table 15). The 280 g rate reduced cotton yields. Table 16 also shows a significant reduction in lint %, although this did riot result in lint yield differences. A lint yield reduc .ion trend from use of CCC seems to be possible. More of a beneficial yield response from CCC treatment would be expected in normal rainfall











37





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ro r"
crj r--4 Ln C-) C:) co CD

r-i C)
0') co co co 00 co 0%0
Ln



4-3

4-)
rt

>1
4-J
(1) Ln rn m (DO I-i
(Y)
m r- CC) C:) U
4) co 00 Co co co 00 H
4-4
r-q

4-t


4J 4
(1)
LI-4
4-4
r-l 4
4

(3) 4-1
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(d Lr) 1 00 C m r-i co 4-) b-,
-P Q) r.
z C C7 C) -1 rd
fd 00 co 00 00

04
rd r--l Lo 04 C)
4-) IV 4J
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Cl -P ::5

>1
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r-I ::5 4-4
0
ro 4- 0
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Q) 4-1 r-A 0 l
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U) U) ro
Q) 4-J 4
0 0
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(Y)

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38

Table 15. Effect of CCC on cotton yield.

CCC rate Seedcotton
g (a.i.)/ha kg/ha

0 1883a

9 1875a

9, 3 times, 10-day intervals 1919a

18 1847a

35 1808a

280 1675 b


1
Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple Range Test.












>1 39

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0 4 a) in rn r-4 co 00 4
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q-1 M "Zil IZIM I:T 1 41 1--il f
4,

D r-i 4
4J
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Ln CIO co co co

CN CN C4 C C 4 C 0\0
Ln
rd
4J X:
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40

years. Evidence exists that CCC may be used at lower rates to obtain desirable effects of modifying vegetative growth without reducing yield.

Fiber strength was increased by CCC at 35 g (a.i.) per ha (Table 16) There were no differences between treatment effects on boll size, fiber fineness, length or uniformity. Nitrogen Rate

Flowering rate and boll set for the initial 3 weeks of fruiting are shown in Table 17. The higher rates of

flowering observed with the 168 kq N rate were not significant. : In contrast, the % boll set was significantly higher in the 85 kg N plots. This resulted in essentially the same number of bolls set for both N rates.

The 168 kg N rate increased cotton plant height (Table 18) This was visually evident from early in the growing season until harvest. This indication of plant vigor was also expressed after defoliant application. High N plots were more difficult to defoliate (Appendix Table 23).

Nitrogen in the leaves was greater in the high N

plants but other mineral elements were not affected (Appendix Table 19).

Even though the 168 kg N rate produced more vigorous plants under the dry conditions, there was no beneficial effect on yield (Table 19). Apparently, the increased % boll set -measured duri-ng the initial 3 weeks of








41

Table 17. Effect of nitrogen rate on flowering and boll set of cotton.1


Nitrogen rate Flowers2 Boll set Boll set

kg/ha no.rq no./m %

84 42 20 49a

168 47 21 44 b



1 Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple Range Test. There are no significant differences between treatments in columns without letters.

2 Flowers tagged daily, five days per week for three weeks immediately following CCC application.







Table 18. Effect of nitrogen rate on cotton plant height.1


Time after CCC treatment, days
Nitrogen rate 15 30 Final
kg/ha cm cm cm

84 79.0 b 82.9 b 81.6 b

168 83.6a 87.5a 88.5a



1 Treatments not followed by the sanme letter differ significantly at the 5% level according to Duncan's Multiple Range Test.








42

flowering continued. throughout the growing season. Dry weather resulted in a shorter than normal fruiting period and boll rot was rnot a factor (Appendix Table 22).

Nitrogen rate had little effect on cotton quality (Appendix Table 21) There were no differences between treatment effects on lint %, boll size, fiber strength., fineness, length or uniformity. Also, rate of fiber elongation was the same, regardless of N rate.

During normal rainfall years, interaction may exist

between CCC and N rate. Dry weather may have been responsible for no interaction in these studies.









Table 19. Effect of nitrogen rate on cotton yield.1

Nitr~ogen rate Seedcotton
kg/h a kg/h a

84 1851

168 1818



1 Treatments are not significantly different at the 5% level according to Duncan's Multiple Range Test.









SUM-ARY

Greenhouse Studies

CCC had no statistical effect on flowering rate during

the initial 4 weeks of flowering in greenhouse studies. There

appeared to be a trend toward CCC treatment increasing % flower set during this period. Flowering rate and boll set

were reduced later in the growing season by CCC rates of 35 and 140 g (a.i.) per ha and greater, respectively. Conse-quently, total boll set per plant was reduced by chemical rates of 140 g and greater. CCC treated plants had shorter mainstem and fruiting branch internodes. Plant height was

retarded from 9 to 33%. Potassium content of leaves was less and N higher in plants treated with the higher rates of CCC. CCC treated plants produced seed with a higher seed index and germination percentage.

Cotton leaf reducing sugars, number of days from open bloom to open boll, lint %, rate of boll development and weight of root systems were not influenced by CCC. However, visual observation of washed roots suggested that CCC may increase the number of fibrous roots.

Low light intensity caused a reduction in flowering

rate, % flower set and number of bolls set per plant. These plants were taller with longer mainstem and fruiting branch internodes than plants subjected to normal light. Low light intensity also increased the interval from flowering to boll maturity.


43








44

Lint percentage, seed index and seed germination were not affected by different light intensities. Field Studies

Below average rainfall probably reduced the degree of

treatment effect in field studies. Height of drought stressed plants was retarded by only the highest CCC rate (280 9 (a.i.) per ha) Calcium and Mn content of leaves was increased by CCC treatment but there was no effect on N, P, Mg, B, Cu, and Zn. CCC increased fiber strength but reduced lint %. There was a reduction in yield at the 280 g CCC rate but no yield differences occurred at lower rates.

In field studies, CCC had no effect on flowering rate, flower set or number of bolls set for the 3 weeks after chemical application. Rate of fiber elongation, boll size, fiber fineness, length and length uniformity were not affected either.

High N increased flowering rate but reduced '. fJower set. High N also increased plant height and N content of leaves and plants were slightly more difficult to defoliate. Cotton yields, fiber quality characteristics, boll sie and rate of fiber elongation were not influenced by N treatment.

Dry weather may have been responsible for no inte.action between CCC and N rates in these studies.









LIERATURE CITED


1. Abdalla, A. A., and K. Verker. 1970. Growth, flowering and fruiting in tomatoes in relation to temperature
Cycocel and GA (gibberellic acid). Neth. J. Agr.
Sci. 18:105-110.

2. Adler, T. 1967. Recent data on CCC experiments.
Novenytermeles 16:211-213.

3. Besemer, S. T. 1969. Response of eckespoint C-1 poinsettia to growth retardants. Calif. Agr. 23:15.

4. Bhatt, J. G., and R. R. Seshad'inathan. 1971. Changes in foliar anatomy of cotton caused by growthretardants. Indian J. Agr. Sci. 40:1142-1146.

5. Bobak, Milan. 1966. The influence of Cycocel (CCC) on the mitotic activity in cells and the disturbance
of cell division. Biologia 21:829-833.

6. Bokhari, U. G., and V. B. Youngner. 1971. Effects of CCC on the growth of wheat plants and their untreated progeny. Agron. J. 63:809-811.

7. Bokhari, U. G., and V. B. Youngner. 1971. Effects of CCC on tillering and flowering of uniculm barley. Crop
Sci. 11:711-713.

8. Bristow, J. Michael. 1966. The effects of gibberellic acid and Cycocel on the growth of cultured leaf
tissue. Can. J. Bot. 44:513-518.

9. Cathy, H. M., and N. W. Stuart. 1961. Comparative plant growth-retarding activity of AMO-1618, phosfon and
CCC. Botan. Gaz. 120:51-57.

10. Gausman, H. W., W. A. Allen, V. I. Myers, R. Cardenas, and
R. W. Leamer. 1970. Reflectance of single leaves
and field plots of Cycocel-treated cotton (Gossypium hirsutum L.) in relation to leaf structure.
Remote Sensing Environ 1:103-107.

11. Gill, D. L. 1962. Growth regulators produce more compact,
budded azaleas. Exchange 138:18-19, 42-43.

12. Gutierrez, O. A. 1967. Effect of timing and dosage of
Cycocel on yield of cotton. Report of Institute
National de Investigaciones Agricolas, Antunez
Michogan, Mexico.

45








46

13. Halevy, A. H., and B, Kessler. 1963. Increased tolerance
of bean plants to soil drought by means of growthretarding substances. Nature 197:310-311.

14. Hamawi, H. 1965. Paper on single and repeated application
of foliar sprays of Cycocel presented to Cotton
Physiology Section, Ministry of Agriculture, OrmanGizer, United Arab Republic.

15. Hore, B. K. and T. K. Bose. 1968. Dwarfing of shrubs
by using chemicals. Bull. Bot. Surv. India 10:165170.

16. Johnson, Lowell B., and John. F. Schafer. 1966. Effect
of (2-Chloroethyl)-trimethylammonium chloride on
Puccinia recondita infection. Plant Dis. Rep.
50:108-109.

17. Khan, A. A., and N. E. Tolbert. 1965. Inhibition of
lettuce seed germination and root growth by indoles
and coumarin and reversal by Cycocel. Plant
Physiol. 40:vii.

18. Kukn, H. 1964. On the decomposition of CCC in soils.
In summary of papers presented at CCC Research
Symposium, Geneva, Switzerland.

19. Kuraishi, S., and R. M. Muir. 1962. Mode of action of
growth retarding chemicals. Plant Physiol. 38:19-24.

20. Larson, Roy A., and Martin L. McIntyre. 1968. Residual
effect of Cycocel in poinsettia height control.
Proc. Amer. Soc. Hort. Sci. 93:667-672.

21. Lindstrom, R. S., and N. E. Tolbert. 1960. Trimethylammonium chloride and related compounds as plant growth substances. IV. Effect on chrysanthemums
and poinsettias. Michigan Quart. Bull. 42:917-928.

22. Linser, H., and H. Kuhn. 1962. Fertilizers for the
control of lodging on the basis of gibberellic acid antagonists of the CCC group (chlorcholinechloride).
Bodenkunde 96:231-247.

23. Linser, H., H. H. Mayr, and G. Bodo. 1961. Ueber die
Wirkung von Chlorcholinchlorid auf Sommerweizen.
Bodenkultur 12:279-280.

24. Marth, P. C. 1965. Increased frost resistance by application of plant growth-retardant chemicals. J.
Agr. and Food Chem. 13:331-333.








47

25. Mayr, H. H., E. Primost, and G. Rittmeyr. 1962.
Untersuchungen ueber die Erhoehung der Standfestigkeit
von Getreide. Feldversuche mit Chlorcholinchlorid
zu Winterweizer. Bodenkultur 13:27-45.

26. McDowell, Ted C., and Roy A. Larson. 1966. Effects of
trimethylammonium chloride (Cycocel), N-dimethyl.
succinamic acid (B-nine) and photoperiod on flower
bud imitation and development in azaleas. Proc.
Amer. Soc. Hort. Sci. 88:600-605.

27. Miyamoto, T. 1962. Effects of the seed treatment with
(2-chloroethyl)-trimethylammonium chloride on the resistances to high and low pH values of soils in
wheat seedlings. Naturwissenschaften 49:377.

28. Monselise, S. P., R. Goren, and A. H. Haleoy. 1966.
Effects of B-nine, Cycocel and benzothiazole oxyacetate on flower bud induction of lemon trees.
Proc. Amer. Soc. Hort. Sci. 89:195-200.

29. Ota, T., N. Chonan, and H. Kawahara. 1964. Science
reports of faculty of agriculture. Ibaraki
University, Japan 9 :1-6.

30. Ota, T., N. Chonan, and H. Kawahara. 1964. Proc.
Crop Sci. Soc. Japan 30:205-210.

31. Primost, E. 1964. The effect of chlorocholine chloride
(CCC) on the growth of germinating wheat seedlings.
Z. Acker. U. Pflanzenbau 119:263-282.

32. Ray, B. R., and V. N. Schroder. 1966. Effect of growth
regulator Cycocel on sunflower plants as affected
by method of application. Soil and Crop Sci.
Soc. of Florida 26:245-248.

33. Read, Paul E., and Vernon C. Hoysler. 1969. Stimulation
and retardation of adventitous root formation by application of B-nine and Cycocel. J. Amer. Soc.
Hort. Sci. 94:314-316.

34. Sachs, R. M., and M. A. Wohlers. 1964. Inhibition of
cell proliferation and expansion in vitro by three
stem growth retardants. Amer. J. Bot. 51:44-48.

35. Singh, Sucha. 1971. Increase cotton production with
Cycocel. Progressive Farmer, Vol. VII:19-20.








48

36. Stoddart, J. L. 1964. Chemical changes in Lolium
temulentum L. after treatment with (2-chloroethyl)trimethylammonium chloride. In Summary of papers
presented at CCC Research Symposium, Geneva,
Switzerland. Cvanamid International, Wayne, New
Jersey, pp. Si-Sli.

37. Stuart, N. W. 1962. Azalea growth rate regulated by
chemicals. Florists' Review (Chicago).

38. Tahori, A. S., G. Zeidler, and A. H. Halevy. 1965.
Effect of some plant growth retardants on the feeding
of the cotton leaf worm. J. Sci. Food and Agr.
16:570-572.

39. Tanaka, Kiichiro, and N. E. Tolbert. 1966. Effect of
cycocel derivatives and gibberellin on choline kinase and choline metabolism. Plant Physiol.
41:313-318.

40. Thomas, R. O. 1964. Effect of application, timing and
concentration of (2-chloroethyl)-trimethylammonium
chloride on plant size and fruiting response of
cotton. Crop Sci. 4:403-406.

41. Thomas, R. O. 1972. Field comparison of selected growth
retardants. Proc. Beltwide Cotton Conf., Memphis,
Tenn. p.49.

42. Tiessen, H. 1962. The influence of various temperatures
and (2-chloroethyl)-trimethylammonium chloride and
(allyl)-trimethylammonium bromide on peppers and
tomatoes. Can. J. Plant Sci. 42:142-149.

43. Tolbert, N. E. 1960. (2-chloroethyl)-trimethylammonium
chloride and related compounds as plant growth
substances. II. Effect on growth of wheat. Plant
Physiol. 35:380-385.

44. Tolbert, N. E. 1964. Mode of action of CCC. In Summary
of papers presented at the CCC research symposium,
Geneva, Switzerland. pp. TI-T3.

45. Wittner, S. H., and N. E. Tolbert. 1960. (2-chloroethyl)trimethylammonium chloride and related compounds as
plant growth substances. III. Effects on growth
and flowering of the tomato. Amer. J. Bot.
47:560-565.





































APPENDIX








5O

Appendix Table 1. Effect of CCC on flowering rate of cotton.1



CCC rate Time from first flower, weeks
1 2 3 4 5 6 7
g (a.i.)/ha flowers/plant

0 0.61 3.17 5.61 6.o50a 6.56 5.39 1.50

9 0.61 3.33 5.06 6.22ab 5.83 4.89 1.22

18 0.50 3.17 5.78 5.89ab 6.28 5.28 1.89

35 0.78 3.17 5.11 5.50abc 6.17 3.39 1.22

70 0.61 3.39 5.17 5.6labc 5.22 3.72 0,94

140 0.67 3.56 5.33 5.17 bc 5.22 3.89 1.06

280 0.78 3.56 5.11 6.llab 489 3.72 0.56

560 0.72 3.67 5.28 4.50 c 4.67 3.83 1.33



1 Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple Range Test. There are no significant differences between treatments in columns that have no letters.









51

Appendix Table 2. Effect of CCC on percent cotton flower set per plant.CCC rate Time from first flower, weeks
1 2 3 4 5 6 7
g (a.i.)/ha flower set/plant,%

0 38.9 87.9 38.6 33.7 40.3a 25.8ab 13.9

9 38.9 89.6 37.4 27.9 43.Oa 36.1a 4.6

18 33.3 92.6 41.4 35.0 39.2a 21.9ab 5.6

35 50.0 91.0 42.8 30.0 26.8abc 36.9a 0.0

70 36.1 92.3 52.3 30.4 30.2ab 21.2ab 0.0

140 38.9 95.9 51.5 26.1 12.0 c 8.8 b 0.0

280 55.6 94.5 54.7 26.8 21.0 bc 7.4 b 11.2

560 33.3 100.0 51.3 19,3 11.5 c 7.4 b 0.0



Treatments not followed by the same letter differ signifi-cantly at the 5% level according to Duncan's Multiple Range Test. There are no significant differences between treatments in columns that have no letters.









52

Appendix Table 3. Effect of CCC on cumulative percent cotton boll set per plant.1



CC rate Time from first flower, weeks
1-4 1-7
g (a.i.)/ha boll set/plant, %

0 48.7 41.3

9 48.8 42.7

18 49.4 39.7

35 52.4 41.6

70 55.1 44.3

140 55.2 40.3

280 55.7 40.2

560 56.8 38.3



1 Results of treatments are not significantly different.









53

Appendix Table 4. Effect of CCC on number of days from open cotton bloom to open boll.1


CCC rate Open bloom
to open boll
g (a.i.)/ha days

0 52.7

9 52.4

18 52.8

35 52.9

70 51,5

140 52.7

280 53.8

560 53.1



1 Results of treatments are not significantly different.









54
a
Appendix Table 5. Effect of CCC on cotton lint percent.

CCC rate Lint

g (a.i.)/ha %

0 41.4

9 39.7

18 39.9

35 39.6

70 38.5

140 39.6

280 39.7

560 38.9



1 Results of treatments are not significantly different.








55

Appendix Table 6. Effect of CCC on rate of cotton boll development and root system weight.CCC rate Age of boll., days
102 20 30 Root System3
g (a.i.)7a g/boll g/boll -7bo 11 g/plant

0 1.57 3.50 4.77 6.95

9 1.55 3.62 4.83 8.66

18 1.54 3.61 4.98 7.01

35 1.71 3.46 5.61 6.18

70 1.50 3.66 5.14 6.26

140 1.68 3.62 5.38 7.51

280 1.32 2.74 4.93 10.03

560 1.60 3.85 5.11 9.68



1 Results of treatments are not significantly different.

2 Dry weight per boll at specified age.

3 Dry weight per root system, 44 days after CCC treatment.
















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60

Appendix Table 11. Effect of light intensity on cotton seed index and germination.! Light intensity Seed index Germination
gi100 seed %

High 12.0 86.6

Low 12.1 85.9

Normal 11.9 88.1



1 Treatments are not significantly different at the 5% level according to Duncan's Multiple Range Test.






Appendix Table 12. Effect of CCC on flowering rate and boll set of cotton.1


CCC rate Boll Boll
Flowers2 set set
g (a.i.)/ha no./m no./m %

0 46 21 46

9 45 21 48

9, 3 times, 10-day intervals 48 21 45

18 42 20 48

35 45 21 47

280 44 20 45


14
Treatments are not significantly different at the 5% level according to Duncan's Multiple Range Test.

2 Flowers tagged daily, five days per week for three weeks immediately following CCC application.









61

Appendix Table 13. Effect of CCC on cotton fiber elongation.1


CCC rate Age of bols, days
10 15 20
g (a.i.)/ha fiber length, mm

0 9.1 14.3 19.1

9 9.4 14.6 19.4

9, 3 times, 10-day intervals 9.4 1.2.4 19.5

18 9.3 13.6 19.9

35 9.8 14.1 19.6

280 9.4 14.0 19.5



1 Treatments are not significantly different at the 5% level according to Duncan's Multiple Range Test.











62

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63

Appendix Table 15. Effect of CCC on cotton yeld.1

CCC rate Cotton lint
g (a.i.)/ha kg/ha

0 761a

9 728a

9, 3 times, 10-day intervals 748a

18 722a

35 696a

280 610 b


1
1 Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's
Multiple Range Test.






Appendix Table 16. Effect of CCC on cotton boll rot.1


CCC rate Seedcotton
rotted
g (a.i.)/ha kg/ha

0 54

9 52

9, 3 times, 10-day intervals 57

18 52

35 37

280 44



1 Treatments are not significantly different at the 5% level according to Duncan's Multiple Range Test.









64

Appendix Table 17. Effect of CCC on cotton defoliation.1

CCC rate Defoliation

g (a.i.)/ha %

0 87.9

9 88.6

9, 3 times, 10-day intervals 89.0

18 88.3

35 89.8

280 87.9



1 Treatments are not significantly different at the 5% leve] according to Duncan's Multiple Range Test.








Appendix Table 18. Effect of nitrogen rate on cotton fiber elongation. 1


Nitrogen rate Age of bolls
10 15 20
kg/ha fiber length, mm

84 9.5 13.5 19.7

168 9.3 14.1 19.3



1 Treatments are not significantly different at the 5% level according to Duncan's Multiple Range Test.








65

Appendix Table 19. Effect of nitrogen rate on mineral content of cotton leaves.l


Nitrogen rate Percent PPM
N__ P K Ca Mg Mn B Cu Zn
kg ha

84 4.0 b 0.3 1.7 3.9 0.7 100 34 20 18

168 4.2a 0.3 1.7 3.9 0.7 111 32 22 18



1 Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple Range Test. There are no significant differences between treatments in columns without letters.

2 Leaf analysis made 30 days after first flower. Results on a dry weight basis.








Appendix Table 20. Effect of nitrogen rate on cotton yield.1


Nitrogen rate Cotton lint
kg/ha kg/ha

84 712

168 710



1 Treatments are not significantly different at the 5% level according to Duncan's Multiple Range Test.













66





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67

Appendix Table 22. Effect of nit20;.,en rate on cotton boll rot.1


Nitrogen rate Seedcotton
rotted
kg/h a kg/ha

84 45

168 53



1 Treatments are not significantly different at the 5% level according to Duncan's Multiple Range Test.













Appendix Table 23. Effect of nitrogen rate on cotton
defoliation.1

Nitrogen rate Defoliation

kg/ha %

84 89.4a

168 87.8 b



1 Treatments not followed by the same letter differ significantly at the 5% level according to Duncan's Multiple Range Test.









68

20
19
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Apeni Fiuel oa anal e ot o 92
s
t 4






L- L


March April M'ay June July Aug. Sept.



LI -TJrty year average rainfall from 1931 through 1960.


Hl 1972 rainfall.


Appr-,mdix Fi-Lre 1. Total rainfall -Der month for 1972, showing departure from normal.











BIOGRAPHICAL SKETCH


CharIcs R. Roland was born September 12, 1938, in

Bleckley County, Georgia. He is a graduate of Cochran High School, Middle Georgia College and received BSA and MSA degrees froT the University of Georgia with a major in Agronomy. In 1962, he was employed with the University

of Georgia Cooperative Extension Service as Assistant County Agent in Twiggs County. He later served as County Agent Chairman in Twiggs and Worth counties. He became a member of the Extension Agronomy Department in 1967 as a Tobacco Agronomist and later as Extension Agronomist Cottor. In June, 1970, he enrolled in the Graduate School of the University of Florida where he is now a candidate for the degree of Doctor of Philosophy.























69









I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy.




E. B. Whit Chairman
Associate Professor of Agronomy

I certify that I have read this study and that in my
opinion it confiforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy.




E.G. fi0'dgeiG
Professor of Agronomy


I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy.





C. F. Douglas
Professor of Agronomy
University of Georgia

I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy.





V. Associate Professor of Arronom
Associate Professor of Agronomy









I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy.




W. G. Blue
Professor (Biochemist) of Soils



This dissertation was submitted to the Dean of the
College of Agriculture and. to the Graduate Council, and was accepted as partial fullfilment of the requirements for the degree of Doctor of Philosophy.

June, 1973



d.Dea College ofAgriculture





Dean, Graduate School