Interspecific Hybrid Fiber Characteristics of Cotton Altered by Unconventional Gossypium barbadense L. Fiber Genotypes

Abstract

Although fiber traits of interspecific hybrids of cotton (Gossypium hirsutum L. × G. barbadense L.) have been manipulated through choice of parent cultivar, the potential range of fiber trait expression in hybrids remains unclear due to limited trait variation in improved G. barbadense germplasm. This study was conducted to determine the effects of unconventional G. barbadense fiber genotypes on hybrid fiber. A second goal was to alter the fiber of interspecific hybrids from a fiber resembling an extra‐long staple (35 mm) cotton to a fiber possessing long staple (30 mm), Acala‐type parameters. Four G. barbadense strains bred for extremely short, coarse fiber and the cultivar Pima S‐6 were crossed to four G. hirsutum cultivars to produce 20 hybrid populations. In four tests of parent and hybrid populations conducted at three locations, parent contribution to hybrid fiber length, uniformity, strength, elongation, micronaire reading, and yarn strength were apparent. Linear regressions of hybrid on G. barbadense parent fiber traits produced an R2 of 0.95 for 2.5% span length and an R2 of 0.52 for micronaire reading. A 0.3‐mm change in hybrid length was estimated for every increase or decrease of 1 mm in the parental fiber. Estimated change in hybrid micronaire was 0.03 units for every 0.1 unit of change in parent micronaire. Heterotic effects in hybrids exceeded responses due to parent contribution and opposed the direction of selection practiced within the G. barbadense parents. Hybrid fiber resulting from the use of short, coarse‐fibered G. barbadense genotypes was unique, fitting neither the long staple or extra‐long staple classifications.