Inheritance of strength of lint in upland cotton
1944
Ware, J.O. | Harrell, D.C.
F1, F2, and F3, first generation backcrosses, and second generation backcrosses were grown from a Florida Green Seed and Rowden cross. Parental lines were grown along with these hybrid groups also and made use of in re-crossing and in backcrossing. The F1 generation was repeated in the second and third years. The first backcross was made with the F1 in 1939 to both parental lines. In 1940 plants in the respective first generation backcrosses were backcrossed again to corresponding recurrent parental plants. The Florida Green Seed stock had the higher strength index which was approximately 1 unit higher than in the Rowden. Strength index determinations were made on this material by use of the Pressley strength tester. In obtaining measurements of the heredity of strength, results varied somewhat, but averages indicate that the inheritance is intermediate with slight tendency to weak dominance. This behavior is such that in repeated backcrossing the level of strength is easily shifted in either direction. Strength in F3 progenies from plants selected out of the several F2 class intervals did not in any case exhibit as much uniformity as shown by either parent, but these F3 plants tended to maintain the F2 level of origin. Seasons affected strength to some degree. In 1939 and 1941 the respective parental lines were at approximately the same level, but higher in 1940. In the several hybrid groups the 1941 level was lower than the 1940 level. Although environment was a factor in this study and doubtless contributed considerably to the expression of variability and in changing season mean levels, the yearly combination or set-up was such that reliable genetic measures appear to have been obtained.
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