Some Genetic Implications in the Transfer of High Fiber Strength Genes to Upland Cotton1

After 30 years of breeding, we have had recent success in overcoming the negative association between lint yield and fiber strength in upland cotton (Gossypium hirsutum L.). Lint yield and yarn strength were measured for at least 2 years on F5 and F6 lines derived from a series of crosses involving intermating and selection in the F2, F3, and F4 generations. Correlation coefficients between lint yield and yarn strength were altered from –0.93 to 0.45 by this process. Several breeding lutes recently developed by intermatings and selection have been successfully crossed to commercial cultivars with and without extra fiber strength genes, whereas previous crosses and backcrosses failed to produce segregates with both high yield and extra fiber strength. Moreover, the frequency of superior and rare plants have increased in the later segregating populations. The importance of linkage, rather than pleiotropism, in controlling the association between lint yield and fiber strength and its implications in breeding is discussed.