The Inheritance of Several Agronomic and Fiber Properties Among Selected Lines of Upland Cotton, Gossypium hirsutum L.1

Abstract

A quantitative genetic study of lint yield, earliness, lint percent, 2.5 and 50% span length, uniformity index, fiber fineness, and fiber strength was conducted in upland cotton, Gossypium hirsutum L., utilizing the Jinks‐Hayman diallel analysis. Ten selected lines and their 45 possible F1 combinations in 1969 and 1970, plus the 45 corresponding F2's in the second year, were included in randomized, replicated experiments at a single location.Analyses of variance indicated highly significant differences among entries for all traits in both years. Partial failures of the diallel assumptions were noted for each trait, although some traits did more nearly comply with those assumptions than did others. Epistasis was not detected as a significant factor for any of the traits. A genotype by environment interaction for the additive components of variation was observed for lint yield, lint percent, and 2.5% span length. The dominance relationships among parents were not constant over years for earliness, lint percent, 2.5% span length, fiber fineness, or fiber strength. Multiple allelism was shown by all traits except fiber fineness; however, gene correlations and parental heterozygosity were not (or could not be) detected for any trait.Overdominance governed lint yield, earliness, lint percent, 50% span length, and uniformity index. Partial dominance was operative for fiber fineness, and complete dominance was indicated for 2.5% span length and fiber strength. Narrow‐sense heritabilities indicated that mass selection should be effective for improving 2.5% span length, fiber fineness, and fiber strength among lines in this material and somewhat less effective for improving earliness, lint percent, 50% span length, and uniformity index. Alternatives, such as pedigrees, sib tests, and progeny tests, must be considered to achieve genetic progress for lint yield in this material.