Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2004
Publication Date: 12/1/2004
Citation: Wu, J., Jenkins, J.N., McCarty Jr., J.C., Zhu, J. 2004. Genetic association of yield with its component traits in a recombinant inbred population of cotton. Euphytica. 149:171-179. Interpretive Summary: Selection for high yielding lines of upland cotton is not an easy task for the plant breeder. Number of bolls per unit area, boll size, and lint percentage make major contributions to lint yield. Each of these is affected by genetics and environment as well as genetic by environment interactions. The plant breeder may thus improve selection for lint yield by selecting for these components of yield. The genotype, environment, and interaction affect each of these components differently. This study describes a new statistical approach to dissecting the genetic and environment effects of the yield components on lint yield. We grew 188 recombinant inbred lines (RI) plus the two parents for two years at Mississippi State, MS, and measured lint yield and yield components. The data were analyzed by an extended, conditional, mixed, linear model. Boll number made the greatest contribution to the genetic and genetic x environment interaction on lint yield. Ninety-nine % of the genetic and environmental variation in lint yield could be explained by these three yield components. The genetic contribution of boll number to lint yield was more widely distributed across the RI lines than was boll size or lint percentage. However, boll size and boll number showed a significant interaction effect. This indicates that a balanced selection for boll number and boll size will be needed when developing high yielding lines of cotton.
Technical Abstract: Lint yield of upland cotton, Gossypium hirsutum L., is determined by several component traits such as boll number, lint percentage, and boll size. Selecting high yielding lines is related to the ability to dissect its component traits. In this study, 188 recombinant inbred lines and two parental lines were grown in 1999 and 2000 at Mississippi State University. Lint yield and its three component traits were measured and analyzed by an extended conditional mixed linear model approach. The results showed that boll number per unit area made the largest contribution to genotypic and genotype x environment (G x E) variations in lint yield. Both boll number and lint percentage, and boll number and boll size jointly made more than 80% of the contributions to genotypic and G x E variations in lint yield. Ninety-nine percent of the genetic and phenotypic variations in lint yield could be explained by these three component traits, indicating that lint yield was mainly dependent on its three component traits. Small phenotypic variation in lint yield could be accounted for by effects of genotype G x E interactions of boll number or boll number combined with other component trait(s). Wider distribution of genotypic contribution effects for boll number per unit area than that for lint percentage and boll size was detected in this study. The results also showed that boll number and boll size interacted to affect lint yield, indicating that a balanced selection for boll size and boll number is needed in developing high yielding lines.