Combining ability for fiber length in near-long-staple upland cotton
Fiber length is one of the most important properties of cotton fibers, with longer fibers allowing for faster processing speeds and a wider array of end products. Four elite, near-long-staple upland cotton (Gossypium hirsutum L.) genotypes with diverse programmatic origins, TAM 94L-25, Fibermax 832, TTU 202, and Acala 1517-99, and one short-staple genotype, Tamcot CAMD-E, were crossed and evaluated in a diallel without reciprocals for six fiber-length measurements at College Station, TX, in 2001 and 2002. Genotypic variation (P ≤ 0.05) and significant general combining ability (GCA) were identified for upper-half mean length (UHML), fiber length by weight (FLw), fiber length by number (FLn), and upper-quartile length by weight (UQLw). Significant variation for specific combining ability (SCA) was identified for FLw, FLn, and short-fiber content by weight (SFCw). Fibermax 832 exhibited the longest fibers for all length measurements, but TAM 94L-25 had the highest GCA effects for UHML, FLw, FLn, and UQLw and thus would be the best parent to use in parental combinations to improve fiber length. The highest desirable SCA effects resulted from the Fibermax 832 x Acala 1517-99 combination. Combining-ability data among these genotypes, which represented diverse U.S. germplasm pools, suggest that most U.S. cotton breeding programs could improve fiber length by using TAM 94L-25 in combination with their breeding lines.