Combining Ability and Variability for Fiber Color among Diverse Cotton Genotypes

Cotton (Gossypium hirsutum L.) fiber color is influenced by biotic and abiotic factors as well as genetics. After boll opening, exposure to the elements modifies fiber color; fibers may become grayer (excessive moisture leading to biotic activity) and lose luster (lower reflectance). Excessive weathering will lead to poorer processing efficiency and lower dye uptake. Genetically whiter cotton fibers could result in reduced use of bleaching agents before dyeing, thus lowering production costs and providing a more environmentally-friendly product. Cotton cultivars TAM B182-33 ELS (Extra Long Staple) and Tamcot CAMD-E were crossed with 12 cultivars from China, 7 from northern Africa, 10 from southern Africa, and 7 from the United States and grown in a line x tester design at College Station, TX during 2010 and 2011. Seedcotton was harvested by hand on the day of maturity, deburred, and allowed to dry in limited light. Lint was separated into 2-g sub-samples, and color measurements were taken using a Konica-Minolta CR-310 reflectance colorimeter. Absolute color measurements were obtained in the CIE L*a*b* color system. General and specific combining abilities for all the variables were determined. Genetic variation existed for all color parameters measured. The cultivars A 7215 (southern Africa), Tejas (United States), PAN 575 (northern Africa), Lintsing Sze Tze 4B (China), F 280 (northern Africa), and Nanging #12 (China) and their F-1 progenies demonstrated superior whiteness. PAN 575 was the best general combiner for whiteness with the two testers in the study.