Genetic Variation for Fiber Properties in Elite Pee Dee Cotton Populations

Abstract

Knowledge of heritability and type of genetic variation involved in the expression of fiber traits would facilitate further improvement of cotton fiber properties. A 4 × 4 Design II mating was employed to estimate magnitude and type of genetic variation controlling fiber traits in populations derived from crossing elite Pee Dee cotton (Gossypium hirsutum L.) parents. Significant genetic variation was found for 2.5 and 50% span length (SL), fiber length uniformity ratio (UR), fiber strength (T1), fiber elongation, and micronaire (MIC). Mating design variances from the F2, F3, and F4 generations of the Design II were resolved into estimates of additive, dominance, and additive epistatic variance for the fiber properties. Dominance genetic variance was greater than additive genetic variance for all of the fiber traits. Additive epistatic variance was detected for 2.5% SL, UR, and MIC. Low single‐plant heritability for all fiber traits suggested that alternatives to a pedigree generation advance beginning with F2 plant selection be considered. Evaluation of F2 bulk populations with a low selection intensity was adequate to identify populations with superior fiber traits. Less than half of the offspring of the top 10% of F3 lines with highest T1 were in the 10% of F4 lines with highest yarn strength (YS). Additionally, the correlation between T1 and YS among 283 unselected F4 lines was only 0.25 (p < 0.05). Maximum progress in improving YS may require selection for traits in addition to T1 or for components of YS not measured by the standard fiber properties.