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The prospect of F2 cotton hybrids offers improved seedling vigor, disease tolerance and yield for the major crop of the Texas High Plains while raising concern about additional fiber property variability. This study attempts to measure whether or not more fiber variability is introduced in the F2 generation than is naturally present in a pure line cultivar or F1 hybrid. A four-parent complete diallel mating system using lines with similar and divergent fiber types results in twenty-eight treatments: four parents, twelve F1 hybrids and twelve F2 hybrids. The log (variance) of ten plants in each treatment is analyzed by a randomized block design analysis of variance with three blocks. Subsets of the treatments (parents, F1s, and F2s) and orthogonal contrasts [parents vs. F1 and F2, F1 vs. F2; parents and F1, vs. F2, wide F1 vs. wide F2 (fineness), wide F1 vs. narrow F1, wide F2 vs. narrow F2 (fineness); wide F1 vs. narrow F1(1), wide F2 vs. narrow F2 (length/strength)] are analyzed. When environmental influence is high, strength and standard fineness show more variability in the F2 than in the F1 hybrid. The higher variability for strength and standard fineness disappears when environmental influence is minimal; the variability that does occur, both in the F2 hybrid and in the F2 hybrid, appears to be a function of original parental variability, especially for fiber fineness or agronomic properties. When original parental variability is low and the strength and standard fineness of the two parents are similar, fiber variability in the F2 hybrid should be no greater than variability on a single plant. |
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©National Cotton Council, Memphis TN |
Document last modified Sunday, Dec 6 1998
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