Cotton Cultivar Response to Planting Date on the Southeastern Coastal Plain

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Abstract
Farmers in the Southeast are interested in growing cotton (Gossypium hirsutum L.) following a winter cash crop or a legume cover crop. This results in a relatively late planting date. Late planting of cotton is now possible because eradication of the boll weevil in some locations has extended the effective period for boll production. Additionally, modern cotton cultivars are earlier in maturity than those previously available. Our objective was to determine the effect of five planting dates on yield, height, and fiber properties of six cotton cultivars: Coker 130 and DES 119 (early), Coker 320 and PD‐3 (medium), and Deltapine 5415 and Deltapine Acala 90 (late maturing). Cotton was planted in mid‐April, early‐ and mid‐May, and early‐ and mid June in 1991, 1992, and 1993. As planting date was delayed, yields decreased 2 of 3 yr, but were unaffected the third year when drought conditions limited yields. As planting date was delayed, lint percentage declined, plant height increased, fiber strength increased, fiber elongation increased, and micronaire declined. Over all years and planting dates, DES 119, Coker 130, and Deltapine 5415 had the highest yield. Deltapine 5415, a longer maturing cultivar, yielded less than the two other cultivars when planted on the later planting dates. Coker 130 had the highest lint percentage and lowest fiber strength, whereas Deltapine Acala 90, the tallest cultivar, had the lowest lint percentage and highest fiber strength. DES 119 had a lint percentage equal to that of Coker 130, as well as the highest fiber uniformity. Fiber elongation and micronaire were highest for Deltapine 5415 and DES 119. These data indicate cultivar selection is an important consideration when planting at a later than optimum date.Research Question: Farmers in the Southeast are interested in growing cotton following winter wheat, canola, or a legume cover crop, thus necessitating a relatively late planting date. Late planting of cotton is now possible because eradication of the boll weevil as an economic pest in some locations has extended the effective period for boll production. Additionally, modem cotton cultivars are earlier in maturity than those previously available. These factors suggest the need to re‐evaluate cotton planting date recommendations. This study evaluated six cotton cultivars planted bimonthly over 60 d to determine the effect of planting date on yield and fiber qualities of cotton grown on the southeastern Coastal Plain.Literature Summary: Numerous studies have shown that cotton has an optimal planting date that will produce the highest lint yield for a particular field, and that the best planting date varies each year. Lower yields obtained by planting later than the optimum date were often explained by a reduced growing season length. Delayed planting had various effects on fiber length, whereas late planted cotton has increased fiber strength but decreased fiber fineness. Research results with modem, early‐maturing cultivars are not available.Study Description: Six cotton cultivars were planted bimonthly from early‐April to mid‐June in 1991, 1992, and 1993 near Blackville, SC. Cotton cultivars evaluated were Coker 130, DES 119, Coker 320, PD‐3, Deltapine 5415, and Deltapine Acala 90. These cultivars represented several commonly grown cultivars and a suspected range of maturities. The experiment was conducted on a Dothan loamy sand the first and third years, and on a Varina loamy sand the second year. Extension Service recommendations were followed for management of production practices. Phosphate and K were applied according to soil test results. All treatments received approximately 66 lb N/acre as S‐25 (14% nitrate‐N, 26% ammonium‐N, 60% urea‐N, and 14% S). Seeding rate was approximately 4.5 seeds/ft, or 13 lb/acre. Weeds, insects, and nematodes were controlled with appropriate pesticides. Cotton from each plot was harvested with a spindle picker and samples of the harvested cotton were ginned on a lab 10‐saw gin to determine lint percentage. Fiber from these samples was used to determine fiber properties using HVI methodology with a Motion Control 350 High Volume Instrument. Properties included micronaire, length, uniformity, strength, elongation, and color.Applied Questions: What are the best planting dates for cotton to optimize lint yield and fiber properties?As planting date was delayed, yields decreased in 2 of 3 yr, but were unaffected the third year when drought conditions limited yields (Table ). In the 2 non‐drought years, the mid‐April planting date resulted in the highest lint yields, and yields declined by approximately 5% for the early‐ and mid‐May plantings, 25% for the early‐June planting, and 67% for the mid‐June planting. In 2 of 3 yr, soil conditions were too wet to permit planting until the mid‐April date.Should different cultivars be planted as planting dates are delayed?Although there were significant year × planting date, year × cultivar, and planting date × cultivar interactions over all years and planting dates, DES 119 had the highest yields, which were similar to those of Coker 130 and Deltapine 5415 (Table ). Deltapine 5415, a longer‐maturing cultivar, yielded relatively better for the earlier planting dates, whereas the two other early‐maturing cultivars yielded more the later planting dates. These results suggest there may be reason to plant shorter season cultivars such as DES 119 or Coker 130 if planting is delayed past mid‐May.How does planting date affect plant and fiber quality characteristics?In general, as planting date was delayed plant height increased, fiber strength increased, fiber elongation increased, and micronaire declined, however, the changes in fiber quality would not affect the price growers would receive. Coker 130 generally had the highest lint percentage and lowest fiber strength, whereas Deltapine Acala 90, the tallest cultivar, generally had the lowest lint percentage and highest fiber strength. DES 119 had a lint percentage equal to Coker 130 and the highest fiber uniformity index. Deltapine 5415 and DES 119 had the highest fiber elongation and micronaire values.Recommendations: Cotton planted by mid‐May on the southeastern Coastal Plain will generally yield more lint than cotton planted after that date. If planting is delayed past mid‐May, shorter season cultivars may have a yield advantage over longer maturing cultivars. While delayed planting may adversely affect some fiber qualities, the changes in fiber quality will not be of the magnitude to result in economic loss. Average lint yields of six cotton cultivars for five planting dates at Blackville, SC.: Planting date Year mid‐April early‐May mid‐May early‐June mid‐June Average ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ lb/acre ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 1991 1541 1355 1490 1088 576 1210a 1992 1283 1321 1172 941 310 1006b 1993 477 514 557 518 581 529c LSD (0.05) between years within planting dates = 76. Average 1100a 1063a 1073a 849b 489c Values in each row followed by the same letter are not significantly different at the 0.05 probability level. Influence of planting date and cotton cultivar on lint yields averaged over three growing seasons at Blackville, SC.: Planting date Cultivar mid‐April early‐May mid‐May early‐June mid‐June Average ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ lb/acre ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ Coker 130 1085 1074 1058 912 536 933ab DES 119 1120 1053 1186 923 560 968a Coker 320 1027 1000 1050 882 500 892bc PD‐3 1089 1049 1005 810 503 891bc Deltapine 5415 1172 1137 1074 826 408 923abc Deltapine Acala 90 1110 1067 1067 742 426 883c LSD (0.05) between cultivars within planting dates=107. Average 1100a 1063a 1073a 849b 489c Values in each row followed by the same letter are not significantly different at the 0.05 probability level.
Funding Information
  • South Carolina Cotton Board