Breeding Potentials of Noncultivated Cottons. I. Some Agronomic and Fiber Properties of Selected Parents and Their F1 Hybrids 1

Abstract

Using a complete diallel set, we analyzed 12 agronomic and fiber characters in five cottons (Gossypium hirsutum L.), and their F1 hybrids. Two of these were adapted cultivars, and the remainder were Texas race stocks. The cultivars were early and productive at Phoenix, whereas the three race stocks varied widely in earliness, lint characteristics, fruit size, growth habit, and other agronomic characters under consideration. Narrow sense heritability estimates for the 12 characters ranged from 0.04 for date of first flower to 1.29 for 2.5% fiber span length. Estimates of general combining ability were significant for number of bolls/plot, peduncle length, and five fiber traits. Thus, selection for these characters should be effective. Nonadditive variance was significant for nine of the 12 characters measured, and comprised the majority of the genetic variance for three of these nine characters. There were no significant maternal effects. Reciprocal effects were significant for a few character/hybrid combinations. Fifteen of the possible 120 character/hybrid combinations showed specific heterosis. Eleven were positive, three negative, and one that may be neutral in the sense of agronomic fitness. Mean heterosis (F1 vs. midparent) was significant only for date of first flower.