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CROP BREEDING & GENETICS

Heritability and Correlations of Agronomic and Fiber Traits in an Okra-Leaf Upland Cotton Population

USDA-ARS-WCIS Res. Unit, 17053 N. Shafter Ave., Shafter, CA 93263

^* Corresponding author (mulloa{at}pw.ars.usda.gov)

In cotton (Gossypium hirsutum L.), the cost and time to develop and evaluate appropriate genetic populations have limited the number of intensive and complete heritability studies. Herein, three agronomic and 17 fiber quality traits were assessed for heritability and correlation analyses on progeny rows in an okra-leaf cotton population of 208 families. Progenies were advanced in succeeding generations by a single-seed descent. Comparison between F_2:3 and F_2:6 generations for individual traits and individual progeny by trait revealed significant differences between the two generations. Heritability estimates (h² > 0.60), and correlations within and between (r > 0.55) F_2:3 and F_2:6, generations have practical applications for the simultaneous improvement of multiple fiber traits. Fiber strength was positively correlated to 2.5 and 50% fiber span length and negatively correlated to short fiber content. Number of neps was positively correlated to number of seed coats, and short and immature fiber content, and negatively correlated to mean fiber fineness and maturity ratio. The genetic potential for improving agronomic and fiber traits may exist in populations with this alternative leaf morphology, okra-leaf type. Mass selection may be effective for improving most of the above traits (h² > 0.60). However, pedigree, sibs, and progeny tests need to be used to achieve higher genetic progress. Selection may be applied as early as the F₃ when selection units can be replicated. Thereafter, antagonistic trait correlations may become neutral or favorable in later generations, facilitating improvement of fiber quality.

Abbreviations: E1, fiber elongation • millitex, fiber fineness • IFC, immature fiber content • Mic, micronaire reading • no., number • SL 50% and SL 2.5%, fiber span length at 50% and at 2.5% • T1, fiber strength • wt, weight