|May Iii, Oscar|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/1995
Publication Date: N/A
Interpretive Summary: The purpose of this research was to assess the genetic diversity of cotton varieties developed between 1980 and 1990. The pedigrees of cotton varieties were subjected to mathematical analysis to determine the coefficient of parentage based on the probability that two varieties share a gene in common. Knowledge of the coefficient of parentage of varieties is useful to breeders and public policymakers. Breeders can use coefficient of parentage to choose genetically dissimilar parents for a breeding program with the potential to generate new variability for future crop improvement. Public policymakers can use information on the genetic diversity and thus vulnerability of the cotton crop to assess the need to expand the genetic base of cotton.
Technical Abstract: Genetic diversity of cotton (Gossypium hirsutum L.) cultivars has not been extensively quantified. Sustained genetic advance requires that genetically diverse parents be mated to form segregating populations for selection. We assessed diversity among 126 Upland cotton cultivars released between 1980 and 1990 by use of coefficient of parentage (CP). Mean CP among the 126 cultivars was 0.07, implying a genetically diverse group. However, cluster analysis of CP revealed 12 distinct gene pools, with mean within cluster CP=0.25 and between cluster CP=0.04. Overall, clusters corresponded to area of cultivar origin. As a group, CP predicts that Acala type cultivars are more diverse than those bred in the Mississippi Delta or southeastern USA. A trend in germplasm usage in the late 1980's was the repeated mating of genetically related material, or reselection within germplasm, to develop proprietary cultivars. To ensure continued progress in cotton improvement, we suggest that cotton breeders consider the pedigree of parents prior to population synthesis.