Primitive Accession Derived Germplasm by Cultivar Crosses as Sources for Cotton Improvement

Abstract

Cotton, Gossypium hirsutum L., is grown primarily for its spinnable fibers. To meet textile mill requirements and producer demands, both fiber quality and yield must be improved. This study was conducted to compare yield and fiber quality when exotic derived lines were crossed to cultivars. Fourteen germplasm lines with high fiber strength derived from selected primitive accessions were crossed as male parents to each of five cultivars. The F2 populations and parents were grown at two different field locations in 1998 and 1999. Parents and F3s were grown at two locations in 2000. Parents, F2, and F3 populations were evaluated for yield, yield components, and fiber quality traits. Combination of location and year was considered an environment for data analyses. An additive‐dominance, additive × additive (ADAA), and genotype × environment interaction genetic model was used for data analysis. A mixed linear model approach, minimum norm quadratic unbiased estimation (MINQUE) was used to estimate genetic variance components on the basis of the ADAA model. Cultivars had higher yields and lint percentages than germplasm lines. Fiber strength for germplasm lines exceeded cultivars. Lint percentage, boll weight, micronaire reading, elongation, and fiber length were similar between F2 and F3 populations and near mid‐parent values. Both additive and additive × additive (AA) epistatic effects significantly controlled all agronomic and most fiber traits. Significant dominance effects were detected for all traits except fiber elongation. Additive × environment and dominance × environment interaction effects were detected for most traits. Significant AA × environment interaction effects were detected for agronomic traits but not fiber traits. The additive × environment effect was significant; however, it made a small contribution to the total variance. This study suggest that crosses between day‐neutral derived lines from photoperiodic primitive accessions and commercial cultivars may allow both the utilization of heterosis and the use of genetic variation for pure line development.