Genetic Variation in Seed Size in an Introgression Line Population of Upland Cotton

Upland cotton is an important fiber and oilseed crop. Cottonseed size, measured by seed index, is an important seed quality trait that affects seed germination, seedling vigor, fiber yield, and cottonseed nutrient content. However, genetic variation in cottonseed size is highly limited within upland cotton, limiting the genetic gain in cottonseed size. Introgression breeding can alleviate this bottleneck effect by introducing desirable genes from pima to upland cotton. This study was conducted to analyze the seed size from both fuzzy and acid-delinted seeds and to assess the appropriate cottonseed size. In 2022, a population of 1600 cotton introgression lines (ILs) was grown at Leyendecker Plant Science Center, NMSU, while three field tests were conducted in 2023, including NM with all the ILs and MS and TX each with 1000 ILs. The analysis of variance of seed size showed that genotypic and environmental variation were found in both types of seeds. The acid-delinted and fuzzy cottonseeds had a mean seed index of 9.58 g and 11.26 g, while the broad sense heritability was 0.56 and 0.32, respectively. Furthermore, the seed index was not significantly correlated with cottonseed oil and different fatty acids.