Division of Genetics, Indian Agricultural Research Institute, New Delhi-110 012, India
A study to obtain information on different generations of an intervarietal cross (CL20X H14) in cotton on the genetics of yield of cotton per plant, boll weight, boll number and seed index was conducted. Three designs of mating as suggested by Comstock and Robinson (1952) and analysis of generations means (Hayman, 1958), was used for the genetic analysis. The two parents and their F1, F2, backcrosses, F3 progenies of the three designs and F3 progenies from F2 plants used in crosses were examined.
A comparison of generation means showed a significant decrease in F2 over F1 for yield, boll weight and seed index. The intercrosses were, in general, better than F2 and the corresponding F3s. Among the biparental progenies those from design II as compared with those of designs I and HI gave higher mean values for all the characters. The analysis of generation means for main effects and interactions revealed that additive effects were significant for all the characters. The dominance effects were also important except for yield. The additive variance (D) was, in general, of larger magnitude as compared with (H). A2A played a significant role on the inheritance of boll weight and boll number. Out of the three designs, design II appeared to give a more realistic estimates of fixable variation.
