Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/8/2006
Publication Date: 2/2/2007
Citation: McCarty Jr., J.C., Wu, J., Jenkins, J.N. 2007. Use of primitive derived cotton accessions for agronomic and fiber traits improvement: Variance components and genetic effects. Crop Science. 47:100-110. Interpretive Summary: Cotton is an important crop that is grown in warm climates throughout the world. To maintain economic viability cotton yield and quality must be improved. Genetic resources need to be identified and used to enhance important yield and fiber traits. Primitive ancestors of cotton contain diversity for trait improvement; however, many of the accessions have a short-day flowering response and are not readily useable in breeding programs. In this study, 114 accessions selected to flower without being day-length sensitive were crossed to two cultivars, Stoneville 474 and Sure-Grow 747. Parents and off-spring (F2 hybrids) were evaluated in field plots for two years where agronomic and fiber traits were measured. The extended additive-dominance genetic model was used for data analysis. The primary genetic effects controlling agronomic and fiber traits were dominance effects while additive genetic effects were small. Strong heterosis in some F1 and F2 hybrids for most traits would be expected. Performance of primitive accession crosses did not show any consistent pattern with collection location or taxonomic classification of the primitive accessions. These derived germplasm accessions that are not sensitive to day length for flowering may provide favorable gene resources for developing high yielding cultivars or hybrids.
Technical Abstract: Upland cotton (Gossypium hirsutum L.) is cultivated in warmer climates throughout the world. The genetic base of modern upland cultivars is narrow. As yield and fiber quality traits are improved the genetic base should be extended by the incorporation of new germplasm into cultivars. In this study, 114 day-neutral derived primitive accessions were crossed to two cultivars Stoneville 474 and Sure-Grow 747 (female parents). Parents and F2 hybrids were evaluated in field plots for two years where agronomic and fiber traits were measured. The extended additive-dominance genetic model was used and the data were analyzed based on the mixed model approach. The dominance effects were the primary genetic effects controlling agronomic and fiber traits while additive effects were small for most of these traits. Consequently, strong heterosis in some F1 and F2 hybrids for most traits would be expected. The genetic resources from the primitive accessions, based on cluster analyses, did not show any consistent pattern for collection location or taxonomic classification. Results indicate that these day-neutral derived primitive accessions provide genes with significant additive effects for fiber quality traits, while the additive effects for yield improvement was not significantly decreased. Thus, these derived germplasm accessions can provide favorable gene resources for developing high yielding cultivars or hybrids.