Submitted to: Applied Statistics In Agriculture Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/20/2004
Publication Date: 4/1/2005
Citation: Wu, J., Jenkins, J.N., McCarty Jr., J.C. 2005. Distribution of boll number and lint yield by time and position in upland cotton cultivars. Applied Statistics In Agriculture Conference Proceedings. p. 296-309. Interpretive Summary: Bolls are distributed differently over fruiting sites among cultivars of cotton. The fruiting sites that set, mature, and open bolls are under genetic control. Plant breeders are interested in combining genes for boll production from early and late season varieties into one variety with higher yields. Since cotton produces bolls over a period of four to six weeks the opportunity for changing the fruiting pattern in the development of a new variety is a challenge. The research in this manuscript describes a statistical approach to understand the genetic control of fruit setting and maturation among varieties which differ in maturity. Eleven varieties were plant mapped at the end of the season for two years and the distribution of open bolls in terms of time and position on the plant were determined. Weeks two and three of fruiting were the most important times for all varieties; however, varieties differed in importance of the other weeks of fruiting. The largest genotypic variance was in week five and later for both lint yield and number of bolls. These genetic data suggested that breeders should be able to cross varieties which differ in earliness and develop new varieties with the best characteristics of each parent.
Technical Abstract: The time period and position which make the major contribution to total yield and to its variation is important for the field management and breeding for upland cotton, Gossypium hirsutum L. Two-year end-of-season plant mapping data from 11 upland cotton cultivars were analyzed by position and by week. The data showed that the first position in the second and third weeks made the largest contribution to the total boll number and lint yield. The eleven cultivars differed with respect to the earliness but they had similar lint yield at harvest. The early season cultivars produce more yield and more bolls than late season cultivars in the first week of blooming, while the late season cultivars produce more yield and more bolls in the fourth week and later. The genotypic variance was the largest in week 5 and later for both lint yield and boll number. Thus, these results suggested that appropriate field management is required to maintain high yield in weeks 2 and 3 and to obtain maximum yield at late season, especially for late season cultivars. Breeders could be able to cross two cultivars which differ in earliness to obtain high yielding lines.