EXPERIMENT s?ATIO@'L§Ra@&§" _, 24 8-527-6M TEXAS AGRICULTURAL EXPERIMENT STATION B. YOUNGBLOOD, DIRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS BULLETIN NO. 360 JUNE. 1927 DIVISION OF AGRONOMY THE EFFECT OF SPACING AND TIME OF THINNING ON THE YIELD, GROWTH, AND F RUITING CHARACTERISTICS OF THE COTTON PLANT IN I925 AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President STATION STAFFT ADMINISTRATION: *B. YouNoELooD, M. S., P_h. D., Director A. B. CoNNER, M. S., Act_ing D_irecto_r R. E. KARPER, B. S., Acting Vice-Director J. M. SCHAEDEL, Secretary M. P. HoLLEMAN, JR., Chief Clerk J. K. FRANcxLow, Assistant Chief Clerk CHESTER Hrccs, Executive Assistant C. B. NEBLETTE, Technical Assistant VETERINARY SCIENCE: "M. FRANcis, D. V. M., Chief H. SCHMIDT, D. V. M., Veterinarian J. D. JoNEs, D. V. M., Veterinarian CHELHSTRY: _ G. S. FRAPS, Ph. D., Chief; State Chemist S. E. ASBURY, M. S., Assistant Chemist WALDo H. WALKER, Assistant Chemist VELMA GRAHAM, Assistant Chemist ADAH E. STURGIS. B. S., A_ssistant Chemist E. C. CARLYLE, B. S., Assistant Chemist R. O. BROOKE, M. S., Assistant Chemist T. L. OGIER, B. S., Assistant Chemist J. G. EvANs, Assistant Chemist HORTICULTURE: W. B. LANHAM, M. A., Chief H. NEss, M. S., Berry Breeder RANGE ANIMAL HUSBANDRY: J. M. JoNEs, A; M., Chief; Sheep and Goat Investigations LUsR, Ph. D., Animal Husbandman; Breeding Investigations W. H. DAMERoN, B. S., Wool Grader ENTOMOLOGY: F. L. THOMAS, Ph. D., Chief; State Entomologist H. J. REmnARD, B. S. Entomologist W. L. OWEN, JR., M. S., E_ntomol0 ist S. E. McGREGDR, JR., Acting Chie Foulbrood Ins ector OTro ACKENSEN, Foulbrood Inspector GILLIS GRAHAM, Foulbrood Inspector AGRONOMY: E. B. REvNoLDs, M. S., Chief A. B. CoNNER, M. S., Agronomist; Grain Sorghum Research _ ' R. E. KARPER, B. S., Agronomist; Small Grain Research P. C. MANGELsDDRE, Sc. D., Agronomist; Corn and Small Grains _ D. T. KILLOUGH, M. S., Agronomist; Cotton Breeding E. C. CUSHING, B. S., Assistant in Crops P. R. JOHNSON, B. S., Assistant in Soils PLANT PATHOLOGY AND PHYSIOLOGY: J. J. TAuEENRAus, Ph. D., Chief FARM AND RANCH ECONOMICS: L. P. GABBARD, M. S., Chief *B. YoUNcELooD, M. S., P,h. D., Farm and Ranch Economist G. L. CRAWFORD, M. S., Marketing Research Lsiéecialisltvl s G . oRY, . ., razing Research Botanist "**T. L. GAsToN, JR., B. S., Assistant, Farm Records and Accounts ***J. N. TATE, B. S., Assistant, Ranch Records and Accounts RURAL HOME RESEARCH: JEssiE WmTAcRE, Ph. D., Chief SOIL SURVEY: ***W. T. CARTER, B. S., Chief H. W. HAWKER, Soil Surveyor E. H. TEMPLIN, B. S., Soil Surveyor T. C. REiTcn, B. S., Soil Surveyor BOTANY: H. NEsS, M. S., Chief PUBLICATIONS: A. D. JAcKsoN, Chief SWINE HUSBANDRY: FRED HALE, M. S., Chie DAIRY HUSBANDRY: —i—-——~-——, Chief POULTRY HUSBANDRY: R. M. SHERWOOD, M. S., Chief ****AGRICULTURAL ENGINEERING: MAIN STATION FARM: G. T. McNEss, Superintendent APICULTURAL RESEARCH LABORATORY (San Antonio) H. B. PARKS, B. S., Apiculturist in Charge A. H. ALEx, B. S., Queen Breeder FEED CONTROL SERVICE: F. D. FULLER, M. S., Chief . D. PEARcE, Secretary . H. ROGERS, Feed Inspector . H. W000, Feed Inspector“ . L. KIRKLAND, B. S., Feed Inspector W. D. NORTHCUTI‘, JR_, B. S., Feed Inspector xéuw SUBSTATIONS No. 1, Beeville, Bee County: R. A. HALL, B. S., Superintendent No. 2, Troup, Smith County: W. S. HOTCHKISS, Superintendent No. 3, Angleton, Brazoria County: R. H STANsEL, M. S., Superintendent No. 4 Beaumont, Jefierson County: R H. WYCHE, B. S., Superintendent No. 5 ,Temple, Bell County: H. E. REA, B. S., Superintendent N v. 6, Denton, Denton County; P. B. DUNKLE, B. S., Superintendent No. 7, Spur, Dickens County: R. E. DICKSON, B. S., Superintendent No. 8, Lubbock, Lubbock County: D. L. JoNEs, Superintendent FRANK GAiNEs, Irrigationist and Forest Nurseryman No. 9, Balmorhea, Reeves County: J. J. BAYLES, B. S., Superintendent No. 10, Feeding and Breeding Station, near College Station, Brazos County: R. M. SHERWOOD, M. S., Animal Husband- man in Charge of Farm L. J. McCALL, Farm Superintendent No. 11, Nacogdoches, Nacogdoches County: Ha F. MoRRxs, M. S., Superintendent ***No. 12, Chillicothe, Hardeman County: J. R. QUINEY, B. S., Superintendent ***JosEPn C. STEPHENS, M. A., Junior Agronomist No. 14, Sonora, Sutton-Edwards Counties: E. W. THOMAS, B. S., Superintendent W. L. BLACK, D. V. M., Veterinarian V. L. CoRY, M. S., Grazing Research Botanist "*0. G. BABCOCK, B. S., Collaborating Entomologist O. L. CARPENTER, Shepherd No. 15, Weslaco, Hidalgo County: W. H. FRIEND, B. S., Superintendent M. McPnAIL, B. S., Entomologist No. 16, Iowa Park, Wichita County: E. J. WILSON, B. S., Superintendent Teachers in the School of Agriculture Carrying Cooperative Projects on the Station: . W . BILSING, Ph. D., Professor of Entomology IPILEE,Ph. GRouT, M. S., Professor of Dairy Husbandry . ADRIANQE, M. S., Associate Professor of Horticulture D., Professor of Marketing and Finance D. ScoATEs, A. Fg, Professor of Agricultural Engineering H. P. SMITH, B. TAs of June 1, 1927. *On Leave. "Dean, School of Veterinary Medicine. “"*ln cooperation with U. S Associate Professor of Agricultural Engineering Department of Agriculture. "***ln cooperation with the School of Agriculture. SYNOPSIS This Bulletin reports the results 0f work conducted in 1925 at the Main Station Farm, College Station, Texas, to determine the efiect of spacing and of time of thinning on the yield, growth, and fruiting characteristics of cotton, and may be regarded as a companion to Bulletin 340, “The Eflfect of Spacing on the Yield of Cotton.” Late thinning in this test, had the effect of stunting the cotton plants, in general causing them to produce fewer branches, particularly vegetative branches, shorter vegetative and fruiting branches, to produce their first branches higher from the ground, and to have smaller plants both in height and diameter, than plants thinned at the normal or usual time of thinning. In short, late thinning, in this experiment, either prevented or retarded the development of both vegetative and fruiting branches, as compared with normal thinning. Cotton thinned at the usual, or normal time, produced blooms and open bolls earlier and also produced an earlier crop and larger yields than the late-thinned cotton. The close and medium spacings, from 9 to 18 inches, produced the earliest crop. In general, the size of bolls increased as the distance between plants was increased. These results show there were no advantages gained by late thinning. If, however, cotton must be thinned late through ‘uncontrollable circumstances, the results indicate that it would be better to leave more plants to the row than is normally the practice. More stunted plants can be left on an acre without crowding than can plants which grow normally. These results are in agreement with those reported in Bulletin 340 of this Station. CONTENTS PAGE Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5 Review of Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Object of Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Plan of Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. - 9 Seasonal Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10 Data on Vegetative Growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Number of Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Diameter of Stalk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12 Branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Height of stalk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15 Fruiting Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Date of First Bloom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Daily Bloom Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 16 Date of First Open Boll . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Number of Bolls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Size of Bolls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 25 Shedding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 26 Earliness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 26 Data on Yield. i . . . . . . . . . . . . ..i . . . . . . . ..y . . . . . . ..v . . . . . . . . . . . . .. 2'7 Yield of Test Bows. . .- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 27 Yield of Plats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Interpretation of Data on Yield by Student’s Method . . . . . r . . . . .. 29 Border Effect _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 29 The Significance of the Difference in Yield Between Adjacent Spacings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31 Percentage of Lint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 33 Length and Grade of Lint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 34 Summary and Conclusions . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . .. .35 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 36 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 BULLETIN NO. 360 r JUNE, 1927 THE EFFECT OF SPACING AND TIME OF THINNING ON THE YIELD, GROWTH, AND FRUITING CHARACTERISTICS OF THE COTTON PLANT IN 1925 R. H. S'I‘ANSEL The Work reported in this Bulletin was conducted to obtain more information on the effect of spacing and of time of_ thinning on the growth and fruiting characteristics of the cotton plant and the rela- tion of these characters to yield. Experiments on the spacing of cotton have been conducted by the experiment stations in the cotton-growing states from about the time of their establishment. The effect of spacing on yield of cotton has been pretty thoroughly Worked out and the consensus of opinion seems to be that medium to close spacing, 6 to 21 inches, gives the best results, the optimum spacing being dependent upon the soil and climatic condi- tions and also upon the variety of cotton grown. A more recent in- novation has been that of a combination of late thinning and close spacing known as “single-stalk” cotton culture. Certain workers seem to have obtained results which support this method, while many other investigators, working on this phase of cotton culture, have found no advantage in this method. REVIEW OF LITERATURE In 1911, Cook of the United States Department of Agriculture pub- lished a paper on dimorphic branches in tropical crop plants. He states: “Definite dimorphism of branches exists in at least five im- portant tropical plants——cotton, coffee, cacao, the Central American rubber tree (Castilla), and the banana. Each normal plant produces two kinds of branches, with regular differences of form and function. “The factor of branch dimorphism must be taken into account in the scientific study of the structure and habits of all these plants, as well as in the breeding and adaptation of varieties. Systems of cultivation and pruning must be planned with reference to the habit of branching.” Later, in 1912i, Cook (14) advanced the theory that the vegetative branches of cotton could be restricted by crowding the plants in the row during early growth. He states: “If the plants are thinned too early, so that the lower joints are exposed before there is enough foli- age to keep them shaded, the vegetative branches are likely to be put forth at each joint and even from the axils of the cotyledons or seed leaves. But if the plants are allowed to stand closer together or are thinned gradually they may not produce any vegetative branches.” In discussing the advantages to be gained from late thinning, Cook 6 BULLETIN NO. 360, TEXAS AGRICULTURAL EXPERIMENT STATION (15) states: “The essential. feature of the new system is late or more gradual thinning. This makes it possible to leave more plants in the rows than is now customary, and yet injurious crowding is avoided through suppression of the vegetative branches. “The control or suppression of the vegetative branches also permits a11 earlier development of fruiting branches and leads to the produc- tion of an earlier crop. In regions where the period of crop produc- tion is limited, either by short seasons or by the presence of the boll weevil, increased earliness is a means of securing larger yields.” Cook (16, 17, 18, 20) gives additional discussion of this new system. In perfecting this new system of cotton culture which Cook (19) now calls “single-stalk cotton culture,” he states: “By taking account of the specialized habits of branching, it is possible to exercise a much more effective control of the development of the plants, so as to secure earlier crops, larger yields, and greater protection against injury by the boll weevil.” Hastings working at San Antonio, Texas, obtained no differ- e11ces in yield from cotton in varying widths of rows where the number of plants per acre remained the same and where part were thinned early and part late. He attributes the lack of difference in yield to the extreme boll weevil infestation. Meade (28), also working at San Antonio, Texas, compared normal- thinned Acala cotton spaced two feet apart in the row with late-thinned Acala cotton spaced six to eight inches apart in the row. The close- spaced late-thinned cotton gave better results than wide-spaced normal- thinned cotton. These results are shown in the following table: - Close-spaced, Wide-spaced, Characters Studied ‘ Late-thinned Normal-thinned Average number vegetative branches per 25 plants . . . . . .48 to .56 1 .56 t0 1 .72 40-day bloom count per row . . . . . . . . . . . . . . . . . . . . . . . . . 23,189 12 ,574 Number bolls matured per row . . . . . . . . . . . . . . . . . . . . . . . 2,108 848 Weight of 5-lock bolls in grams . . . . . . . . . . . . . . . . . . . . . . . 5 .64 6 .2 Yield per acre, pounds seed cotton . . . . . . . . . . . . . . . . . . . . 1 ,07l 484 Meade obtained similar results in a test where he used alternating four-row blocks, but the difference in yield obtained from the use of the two methods was not as great as in single alternate rows. Since there was less difference in yield of the two methods when four-row blocks were used, it would appear that some factor other than time and rates of thinning was involved. It is probable that where rows of close- ~ spaced plants are adjacent to rows of \V1(l6—Sp2lC8(l plants, the plants on the close-spaced rows utilized plant-food material and moisture from the wide-spaced rows; hence, the plants on the close-spaced rows gave the larger yield. This influence is called “border effect.” In other SPACING AND TIME OF THINNING OF THE COTTON PLANT IN 1925 7 tests Where early- and late-thinned plants were spaced alike, no differ- ences iii yield were secured. These results further indicate that the higher yield of the close-spaced late-thinned cotton reported above were partly due to differences in spacing and partly t0 border effect. Letteer (25, 26), also Working at San Antonio, found that the wide- spaced early-thinned plants yielded better than the late-thinned close- spaced plants. He attributes this difference to the adverse climatic conditions of the two years, although he states the yields in 1917 were satisfactory. At San Antonio in the years 1911, 1915, 1916, 1917, late-thinned close-spaced cotton gave larger yields in only one year out of the four, and in this year only part of the tests gave these results. Since the work in this year, 1915, is open, to serious criticism of having several variables involved, there seems to be little evidence that late-thinned close-spaced cotton gives better yields in the locality in which the tests were conducted. Garrett (21) and Hester (23) at the North Louisiana Station found that early thinning as usually practiced gave better results than single- stalk cotton culture. Ayrres (1, 72) gives results from a test comparing late- and early- thinned cotton in 6- and 12-inch spacings in Arkansas. The yields are given 111 pounds of seed cotton per acre. Each year the highest yield was made by the early-thinned cotton, which also gave the most cotton at the first picking. ' _ Time of Yield, Yield, , Spacing Thinning 1917 1918 Average 6-lnch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Late 1290 1032 1161- 6-inch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Early 1495 981. 1238 12-inch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Late 1422 937 1179 12-inch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Early 1500 1103 1301 McClelland (27) reports several years’ work in Georgia, comparing early- and. late-thinned cotton. However, in each case about twice as ‘ many plants were left i11 the late-thinned plats-as in the early-thinned ones. His results are as follows: Pounds 0f Seed Cotton Per Acre. Year. . .1 . . . . . . . . . . . .. 1914 1916 ' 1917 1917 1918 _ ’ _ Average Variety . . . . . . . . . . . . . Durango Sunbeam Lewis Sunbeam Sunbeam No. 63 Early chopping . . . . . . 766 1850 1390 1585 1109 1340 Late chopping . . . . . . . 638 1878 1265 1521 1041 1248 Blair (6), in Arizona, compared upland cotton with Pima and Yuma varieties. He concluded that the varieties of upland cotton ‘showed a 8 BULLETIN NO. 360, TEXAS AGRICULTURAL EXPERIMENT STATION gain in yield from late thinning, while Yuma and Pima. varieties showed a loss from this practice. Cardon (11) reports experiments with the “single-stalk cotton cul- ture” in Louisiana, Arkansas, and North Carolina, carried on by farm- ers in various localities. Nearly all of the farmers reported slight in~ creases in yield due to late thinning and close spacing. Three out of nine in Louisiana obtained results in favor of early, or normal thin- ning. In all cases the gain was negligible. This Work is open to the serious criticism that two variables, rate and time of thinning, are in- volved. The difference in yield might have been due to differences in the rate of spacing. The early-thinned plants were left 18 to 3O inches apart in the row and the late-thinned ones 6 to 10 inches. Ayres (4) at the Delta Branch Station in Mississippi compared early- and late-thinned cotton of the same spacing. The early-thinned cotton outyielded the late-thinned by 32.4 per cent in the total crop and 89 per cent at the first picking. Brown (9), in summarizing work conducted in Mississippi from 1916 to 1919, inclusive, found no evidence indicating greater productiveness of late-thinned as compared with early-thinned cotton of the same s.pac- ing, and arrived at the following conclusions: “Since there seems to be no experimental evidence to show that increased yields are to be secured through delayed thinning and since there is evidence from three different experiment stations to show that late thinning most fre- quently results in lower yields, it seems that the Single-Stalk Method of Cotton Culture is of very doubtful value. We believe that cotton plants should be thinned as early as it is safe to do so——that is, as soon as the danger of losing a stand from cold weather, damping off fungi, etc., has passed, and before the plants are stunted by undue crowding.” Hall and Armstrong (22) report work at Florence, South Carolina, comparing early and delayed thinning in 1923 and 1924. The plants were spaced 12 inches apart in the row and the late thinning was done at the appearance of the first squares. Their results are given in pounds of seed cotton per acre. Yield, Yield, Avera e 1923 1924 Yiel Early thinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 733 670 702 Late thinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. - 607 548 578 From these results, they conclude that it is not profitable to delay thinning much beyond the stage at which cotton is regularly chopped. Reynolds (29) in Texas has reported the results of experiments on the spacing of cotton conducted at Angleton, Beeville, Chillicothe, and College Station, Texas, over a period of nine years from 1916 to 1924, inclusive. In these experiments, normal and late-thinning were com- pared in 12 rates of thinning var_ving from 3 to 36 inches in three-inch SPACING AND TIME OF THINNING OF THE COTTON PLANT IN 1925 9 intervals. The results secured from this rather exhaustive study show in general that normal thinning produced larger yields than late or deferred thining. OBJECT 0F EXPERIMENT The present work was undertaken to obtain more evidence as to the effect of time of thinning 0n cotton plants spaced the same distance apart in the row in relation to vegetative growth and fruiting charac- teristics, as well as to the yield. Accordingly, a study of the follow- ing characters in cotton plants was made, using in the experiment, twelve different spacings in which normal and late thinning were in- volved: A. Vegetative growth 1. Height of plant 2. Number of nodes in plant 3. Diameter of stalk 4. Number and length of vegetative and fruiting branches 5. l Height of first branch from the ground B. Fruiting characteristics 1. Daily bloom count 2. Date of first open boll 3. Number and size of bolls 4. Amount of shedding 5 Earliness C. Yield and character of lint I PLAN OF EXPERIMENT The Work reported in this Bulletin was conducted in 1925. Two acres on the Main Station farm at College Station, Texas, were devoted to this experiment. The soil, Lufkin fine sandy loam, was fertilized with a mixture of 200 pounds of 16 per cent acid phosphate and 100 pounds of cottonseed meal to the acre. Twelve spacings were used in which the plants were left 3, 6, 9, 12, 15, 18, 21, 24, 2'7, 30, 33, and 36 inches apart in the row. Each appeared six times in both the normal- and the late-thinned plats. Each plat consisted of three 3-foot rows 64 feet long. The center row was the test row and the outside rows were used as guard or border rows. Several feet were left on each end of the row as border spaces to eliminate border effect, which was noticable in most cases. This cotton was planted on May 1, 1925. DEFINITIONS OF TERMS Thinning The cotton plants were thinned by pulling up the plants by hand. A plaster lath marked off at the proper distances was used in thinning the plants to the stand desired. 10 BULLETIN NO. 360, TEXAS AGRICULTURAL EXPERIMENT STATION N0flna1 Thinning! The term normal thinning as used in this Bulletin has reference to cotton thinned at the usual chopping time as prac- ticed by most farmers in the thinning of their cotton, which usually is done when the plants have four to six leaves. Late Thinningl In this series of plats thinning Was delayed until the plants were about six inches high and squares were forming, which was 28 days later than the thinning of the normal-thinned cotton. The plats to be thinned at the llOfllldl time received their preliminary thinning on May 18. 'l.‘wo plants were left to the hill in the wider spacings, while in the 3-, 6-, and 9-inch spacings a few more plants than were required for a perfect stand were left. This was done to take care of any loss of plants through dying and at the same time to prevent the effects of late thinning. The final thinning on these plats was given on June A considerable number of plants had died, especially in the closer-spaced rows, due to the unusually dry Weather. The late-thinned plats were thinned to the required stand at the first thinning on June 16. The three-inch-spacetl rows required very little thinning, as many of the plants had died previously to thinning. Consequently, there could be very little effect from late, or deferred, thinning in the plats of this spacing. - _ The stand was not as uniform as was desired, since a few plants continued to emerge for several weeks. At the final thinning a num- ber of very small plants which were apparently’ only a few days old were pulled. This late emergence of many plants, together with the death of many others, partly accounts for some of the discrepancies in the stand obtained as shown by the count of plants taken on September 16 after five pickings had been made. The discrepancies were in no case great and it was thought better not to regroup the plats, as no changes would be made in the plats spaced less than 18 inches, and the changes in the plats spaced more than 18 inches were not significant. Most of the discrepancies occurrediin the 30-, 33-, and 36-inch spac- ings, where one or two plants would make considerable differences in stand. Seed Used The cotton seed used in this test was home-grown seed of the Startex variety, Texas Station X0. 7 000, a strain of Lone Star, originated at this Station. It is a high-yielding strain, “Yell adapted to this locality. The seed was culled mass-selected stock seed and was very uniform. SEASONAL CONDITIONS The crop season of 1925‘ was abnormally dry. The daily precipita- tion is shown in Table 1. The year 1924 had also been very dry and there was little reserve moisture in the soil available in 1925. The crop was started on the showers during the latter part of April and prac- tically the entire first crop of cotton was made from the rain of 1.4.4 inches on June '20 and the rain of .13 inch on July ‘l0. May and the SPACING AND TIME OF THINNING OF THE COTTON PLANT IN 1925 11 first half of June were very dry and the cotton suffered considerably, grew very little, and, before the rain of June 20 came, the plants wilted during the ‘middle of the day. The rain of August 26 and the rains in September caused renewed growth of the plants and, consequently, a top crop was set, many of the bolls setting after the middle 9f Sep- tember. The excessive rains in October were too late to be of benefit to the cotton crop. The abnormal growing season should be borne in mind when one examines the results secured in this test. ffable 1.——Daily Precipitation in Inches at Main Station Farm, College Station, Texas, 1925. ' I . Jan. Feb. Mar. April May June July Aug. Sept. Oct. Nov. Dec. .11 .06 132...... T* .28.. 1.95. T 1.13 .07 .05.. . 01 . 04 .02 .02 .43 .19..... .02 .50..... .03 T .58 3.19. .26 T .O7.....1.36.......... .17..... .14 . . . . . . . . .47..... .07 .87 T 1.84..... .50 .O4..... 1 . . . . . . . . . . . . .17..... .30....... » . . . . . . . . . . . . . .05 .25..... t: . . . . . . . . . . . . .61..... ‘T .65 .86..... .09 . . . . . . . . . . . . .. l.‘ Total . . . . . . .. 1.72 0.62 0.38 1.95 0.02 1.67 1.12 2.54 30211.62 5.82 0.99 _ *Trace. - Total for the year, 31 .47 inches. DATA ON VEGETATIVE GROWTH A‘ fjAll plant measurements were taken on the test rows. A section of consecutive plants, which appeared to be representative of the row -_.a. Whole, was selected for these measurements. In the wider spac- s this included the majority of the plants, While in the case of the er spacings only a small proportion was represented. It is believed the measurements were representative for each test row. i‘ ll measurements except those on height of stalk were taken from tember 1 to September 16. The height of the stalk at the first pick- _ was taken on August 8, and the height at the last picking on J an- “ 9, 1926. All measurements were made in centimeters. 12 BULLETIN NO. s60, TEXAS AGRICULTURAL EXPERIMENT STATION In each case the average for the 20 plants on each test row was secured and the average of the six repetitions was secured for each of the 24 tests, each average representing the measurements of 120 plants. In measuring the branches, averages were taken of the 2O plants as a group and not as individuals. Thus the total number of branches on the 20 plants was divided into the total length of all the branches on the 20 plants to get the average length. In this way all the plants on a row were treated as a group and not individually, as this was thought to be a better Way of visualizing the actual conditions within the row. Number of Nodes The increase in the number of nodes above ground seemed to keep pace pretty closely with the increase in the spacing of the plants in both the normal- and late-thinned cotton, the plants of the wider- spaced cotton having a larger number of nodes. (Table 2.) There was greater variation, however, in the late-thinned than in the nor- mal-thinned cotton. These differences appear to be of little significance. Table 2.——The effect of spacing and time of thinning on the number of nodes. 21 Spacing, Inches 3 6 ‘ 9 ‘ 12 15 18 24 27 k 30 33 36 Normal . . . . . . . . .. 11.7 13.8 14.7 16.3 16.5 16.7 17.9 18.1 18.4 18.7 18.8 19.6 Late . . . . . . . . . . . .. 13.0 14.6 14.9 16.2 16.1 17.2 17.7 17.1 17.4 18.2 17.8 18.6 Diameter of Stalk Apparently there is a high correlation between the diameter of the - stalk and the spacing, the wider spacing giving plants with stalks of a greater diameter, as shown in Table 3. A comparison of the normal- and late-thinned cotton shows that the former had larger stalks in the 12-inch and wider-sp-aced cotton, while the latter had larger stalks in the 3-, 6-, and 9-inch spacings. The difference in favor of the late- thinned cotton in these closer spacings is small and is probably of little significance. Table 3.—The eifect of spacing and time of thinning on the diameter of the stalk, measure- ments in centimeters. a Spacing, Inches 3 6 9- 12 15 18 21 24 ‘ 27 30 33 36 Normal . . . . . . . . . . .395 .491 .538 .625 .674 .709 .739 .764 .814 .837 .830 .883 ~ Late . . . . . . . . . . . .. .412 .508 .553 .592 .610 .666 .659 .683 .691 .703 .720 .732 a Branches The branches of ‘the cotton plant are usually classified as fruiting and vegetative branches. The fruiting branches bear the fruit directly j SPACING AND TIME OF THINNING OF THE COTTON PLANT IN 1925 13 on the branch While the vegetative branches bear the fruit on sub- branches, which may be short or long, depending on the variety and growing conditions. . _At the time the plants were measured it was found that a number of the branches were devoid of fruit or sub-branches or even leaves in many cases. These were often merely stubs and it was impossible t0 determine whether they were vegetative or fruiting branches. The majority were probably fruiting branches but it would not be a fair criterion of the proportion of the vegetative and fruiting branches to include these doubtful branches under either of these two classifica- . tions. If these branches -were disregarded it would mean the elimina- L‘ tion of a majority of the branches on many of the plants. It was .. thought best to include these branches under the classification of “doubtful branches.” Only the branches on the main stalk are in- cluded in the measurements and they were measured to the nearest half centimeter in length. . N-llmbel‘ 0f Brflllchesi The total number of branches, and the number . of vegetative, fruiting, and doubtful branches are given in Table 4. f_ There is a positive correlation between the total number of branches {and the rate of thinning, the same holding true for the number of 1 vegetative and of fruiting branches. Spacing produced less variation fin the number of doubtful branches than in the number of vegetative Q 0r of fruiting branches. In the 3-, 6-, and 9-inch spacings the majority ‘of branches were classed as doubtful. iTable 4.—-T he effect of spacing and of time of thinning on the number of branches per plant. Number of Branches Per Plant Vegetative Fruiting Doubtful SIpaching Total Branches Branches Branches nc es Normal Late Normal Late Normal Late ’ Normal Late Thinned Thinned Thinned Thinned Thinned Thinned Thinned Thinned 2.96 3.66 0.00 0.00 0.80 1.22 2.16 2.44 . . . . . . . . . . .. 5.12 5.80 0.05 0.06 1.86 2.63 3.21 3.11 . . . . . . . . . . .. 6.45 6.76 0.16 0.16 2.38 2.96 3.91 3.64 . . . . . . . . . . .. 8.54 7.98 0.39 0.31 3.71 3.91 4.44 3.76 9.45 8.56 0.43 0.16 4.34 4.28 4.68 4.12 9.72 8.96 0.51 0.31 4.85 4.61 4.33 4.04 . . . . . . . . . . . .. 11.32 9.73 0.75 0.21 5.43 5.51 5.14 4.01 11.04 9.41 0.71 0.26 5.37 5.06 4.96 4.09 11.77 9.61 0.81 0.22 6.05 5.68 4.91 3.71 12.16 10.24 0.89 0.31 6.52 5.64 4.75 4.29 f. 11.64 10.11 0.80 0.41 6.50 5.71 4.34 3.99 ’ . . . . . . . . . . . .. 12.21 10.83 1.15 0.32 6.76 6.50 4.30 4.01 u The late-thinned cotton had more branches than the normal-thinned jotton, from the 3- to the 9-inch spacing, inclusive. The number of legetative branches, however, is approximately the same in each case. i om the 12-inch to the 36-inch spacing the normal-thinned cotton as more branches than the late-thinn.ed cotton. This is strikingly oticeable in the case of vegetative branches. 14 BULLETIN NO. 360, TEXAS AGRICULTURAL EXPERIMENT STATION Length 0f Branches! The data 0n length of branches are given in Table 5. As a whole, the wider spacings had longer branches than the narrower spacings and the normal-thinnetl plants had longer branches than the late-thinned plants. The variation in the length of the vege- tative branches is probably due to the small number present. Table 5.——The effect of spacing and of time of thinning on the length of branches. Length of Branches in Centimetcrs Vegetative Branches Fruiting Branches Doubtful Branches Spacing, Inches Normal Late Normal Late Normal Late Thinned Thinned Thinned Thinned Thinned Thinned Cm. Cm. Cm. Cm. Cm. Cm. 0.0 0.0 1.7 2.4 1.7 ’1.7 7.6 7.5 2.5 2.8 2.4 2.3 10.6 12.2 3.0 3.3 2.9 2.7 10.5 9.9 3.8 3.6 3.3 2.9 14.7 9.1 4.5 4.0 3.9 2.7 12.9 12.7 5.0 4.1 4.3 3.0 12.0 14.1 5.8 4.4 4.5 3.4 13.3 11.7 6.1 4.6 4.7 3.4 16.1 10.9 6.9 4.7 5.1 3.3 15.4 14.1 7.3 5.1 5.7 3.8 15.3 14.3 6.8 4.8 5.4 3.6 16.6 14.9 7.6 5.8 5.5 4.7 Height 0f First Branch from the Ground: There Wag (jgngjderable variation in the average height of the first branch from the ground, as shown in Table 6. However, the data show quite conclusively that the closer-spaced plants bear the first branch a greater distance from the ground than the wider-spaced plants. This holds true both for the normal and the late thinnings. Table (i-Efiect of spacing and of time of thinning on the height of first branch from . surface of ground. Height from Ground of First Branch First Vegetative First Fruiting First Doubtful Spacing, of Any Kind Branch Branch Branch Inches Normal Late Normal Late Normal Late Normal Late Thinned Thinned Thinned Thinned Thinned Thinned Thinned Thinned Cm. Cm Cm Cm Cm Cm Cm. Cm 3 . . . . . . . . . . . .. 11.8 12.5 . . . . . . . . . . . . . . .. 14_.7 17.3 11.9 12.5 6 . . . . . . . . . . . .. 11.0 12.2 9.8 11.1 14.8 15.8 12.0 12.8 9 . . . . . . . . . . . .. 10.3 10.3 8.5 8.5 14.1 14.5 11.6 11.6 12 . . . . . . . . . . . .. 9.7 10.0 10.9 12.2 14.3 14.6 11.7 10.9 15 . . . . . . . . . . . .. 8.1 8.7 7.5 8.3 13.5 13.7 10.4 9.9 18 . . . . . . . . . . . .. 8.2 9.5 9.0 10.8 13.2 14.5 10.3 10.7 21 . . . . . . . . . . . .. 7.9 8.7 10.2 7.7 14.3 13.4 8.9 9.4 24 . . . . . . . . . . . .. 8.3 9.7 9.2 9.2 13.6 14.8 10.1 11.1 27 . . . . . . . . . . . .. 7.4 9.2 8.5 10.1, 13.4 13.4 9.8 10.8 30 . . . . . . . . . . . .. 7.4 8.8 9.3 9.6 13.4 14.2 10.2 10.1 33 . . . . . . . . . . . .. 8.2 8.3 9.2 10.3 13.3 13.1 11.4 9.5 36 . . . . . . . . . . . .. 8.8 8.4 9.9 9.1 15.3 14.4 11.7 9.4 The average height of the first. vegetative branch from the ground was quite variable and might have been due to the small number present. In the case of the height of the first fruiting branches there SPACING AND TIME OF THINNING OF THE COTTON PLANT IN 1925 15 was little difference in any of the spacings in the plats thinned at the normal time. In the late-thinned cotton, the 3- and 6-inch spacings bore their first fruiting branches farther from the ground than the wider-spaced cotton. This difference is apparently significant. The first doubtful branch seemed to be at a height from the ground inter- mediate between the first fruiting branch and the first branch of any kind. Height 0f Stalk At First Picking! Table '7 gives data 011 the height of stalk at the first picking. There was considerable difference in the height of the stalk in the various spacings and also in the normal and late thinnings. There was a progressive increase in height of plants as the distance be- tween the plants increased, which was, however, not so marked in the late-thinned cotton, there being little (lifference in the spacings Wider than 18 inches. However, in the normal-thinned cotton the increase was rather regular throughout. Table 7.—The eiTect of spacing and time of thinning on the height 0f stalk at first picking, measurements 1n centimeters. Spacing, Inches ‘ 3 . 6 9 12 1'5 18 21 24 27 3O 33 36 Normal . . . . . . . . .. 14.6 17.7 21.4 24 8 26.2 27.7 29.7 29.2 31.8 31.7 30.8 33.2 Late . . . . . . . . . . . .. 16.3 19.1 19.7 2O 7 20.5 21.4 21.3 22.4 21.9 22.9 22.9 22.9 The late-thinned cotton was somewhat taller than the normal-thinned cotton in the 3- and 6-inch spacings, but the latter was considerably taller in all the other spacings, the difference in some cases amounting to 5O per cent. Table 8.—The effect of spacing and time of thinning on the height of stalk at last picking. Measurements in centimeters. Spacing, Inches 3 6 9 12 15 18 21 24 27 3O 33 36 Normal . . . . . . . . .. 21.9 26.4 31.2 33.6 37.6 36.8 39.4 39.2 43.4 42.0 42.9 47.87 Late . . . . . . . . . . . .. 25.5 26.1 315 33.1 33.2 35.1 35.7 36.2 36.8 37.5 35.9 41.3 At Last Picking! Table 8 reports data on height of stalk at last; picking. As in the height of the stalk at the first picking, the height of the stalk at the last picking increased as the distance between the plants increased. However, the plants made considerable grmvth be» tween the first and the last pickings. The late-thinned cotton grew more in proportion to the height at the time of the first picking than did the normal-thinned cotton. This seems to indicate that the late thinning stunted the plants to a certain extent and they did not recover until the rains began late in the season. They never reached the height of the normal-thinned cotton except in the 3-, 6-, and 9-inch spacings, Where the late-thinned plants already had the advantage. 16 BULLETIN NO. 360, TEXAS AGRICULTURAL EXPERIMENT STATION FRUITING CHARACTERISTICS Date 0f First Bloom The first bloom opened on June 18. The number of days after June 1'7 thatthe first bloom opened on each test row was taken as the date of first bloom for that row. Table 9 shows the average number of days after June 17 that the first bloom opened for each rate of thinning. Table 9.——The effect of spacing and time of thinning on the date of first bloom. Measured in days from June 17 Spacing, Inches 3 6 9 12 15 18 21 24 27 3O 33 36 Normal . . . . . . . 4.8 6.0 6.6 5.3 4.6 6.1 5.5 6.6 6.3 6.0 5.1 7.0 Late . . . . . . . . . . . .. 6.0 6.6 6.1 7.3 6.3 6.8 9.3 6.5 8.6 7.6 7.1 8.0 The spacings showed little uniformity in the date of the first bloom with the exception of the late thinning, where the spacings from three to nine inches seemed to bloom a little earlier than the wider spacings. A comparison of the normal and late thinnings shows that the nor- mal-thinned cotton bloomed earlier in almost every case than the late- thinned cotton. Daily Bloom Count The blooms were counted daily on all the test rows from the date of the first bloom, which occurred on June 18, until September 18, a period of 93 consecutive days. The counts were made in the morning after the blooms had opened but before they had become pink in color. The daily bloom counts are given in graphic form in Figures 1 to 13, inclusive. The average cumulative bloom counts on the test rows by periods are given in Table 10. It is noticeable that the closer spacings gave a larger bloom count than the wider spacings. In gen- eral, the number of blooms decreased as the distance between the plants increased, and in the late thinning there were no exceptions to this. Table 10.—-The effect of spacing and of time of thinning on the number of blooms produced during different periods. Number of Blooms Produced from June 18 to Slimelilng, July 1 July 16 August 16 September 18 nc es Normal Late Normal Late Normal Late Normal Late T binned Thinned Thinned Thinned Thinned Thinned Thinned Thinned 3 . . . . . . . . . . . . . 74 72 334 344 537 583 674 748 6 . . . . . . . . . . . . . 63 o2 312 278 495 497 617 630 9 . . . . . . . . . . . . . 73 44 333 212 477 406 589 521 12 . . . . . . . . . . . . . 77 38 318 176 493 374 637 494 15 . . . . . . . . . . . . . 64 33 288 128 423 297 550 396 18 . . . . . . . . . . . . . 60 27 286 119 432 279 560 379 21 . . . . . . . . . . . . . 42 19 234 96 389 239 498 331 24 . . . . . . . . . . . . . 33 16 193 85 363 229 456 311 27 . . . . . . . . . . . . . 36 15 214 76 384 215 483 309 30 . . . . . . . . . . . . . 35 13 187 69 366 203 453 295 33 . . . . . . . . . . . . . 23 16 144 80 310 207 393 289 36 . . . . . . . . . . . . . 24 11 148 63 329 190 411 280 §hv‘* _ ._‘...-.._.....‘_. SPACING AND TIME OF THINNING OF THE COTTON PLANT IN 1925 17 Fig. 1.—Number of blooms counted daily in 3-inch spacing of normal- and of late-thinnedlcotton 1mm " amass-a sauna. § §fi QQ§QQQ$§QQ §§§§ ' i‘ fiflfifigéfigfiy wmaufifis ~ . rs Fig. 2 -—Number of blooms counted daily in 6-inch spacing of normal- and of late-thinned cotton 18 BULLETIN NO. 360, TEXAS AGRICULTURAL EXPERIMENT STATION Kevan} “w”... so so . saunas or ante ‘ ' » Fig. 3.~—Number of blooms counted daily in 9-inch spacing of normal- and of late-thinned cotton Fig. lL-Number 0f blooms counted daily in 12-inch spacing of normal- and of late-thinned cotton SPACING AND TIME OF THINNING OF THE COTTON PLANT IN 1925 19 Fig. 5.—i—Number of blooms counted daily in 15-inch spacing of normal- and of late-thinned cotton vgpggog; as axaeua Fig. 6.——Number of blooms counted daily in 18-inch spacing of normial- and of late-thinned cotton 2O BULLETIN NO. 360, TEXAS AGRICULTURAL EXPERIMENT STATION Fig. 7 .—N umber of blooms counted daily in 21-inch spacing of n0rmal- and of late-thinned cotton q a. n '3 xtati'a\n_gvo