Heterosis and line-tester analysis of intra-Gossypium barbadense L. hybrids. I. Yields, plant canopy and earliness.

In a 3 x 11 line-tester analysis, the extent of heterosis over midparent (MP), better parent (BP), commercial checks for yield and fibre quality was calculated in intra-G. barbaunse L. hybrids. Lines and testers produced 51.8–69.1 g/plant seed cotton, and the eight top yielding hybrids 15.9–93.3 g/plant, nearly equalling that of interspecific hybrid DCH-32 (94.8 g). Ginning outturn of hybrids was 30.6–34.4% of the best line. The hybrids were 20–28 days earlier and showed similar plant canopy characters. Heterosis for seed cotton yield over the cultivars was 11.3–81.1%. Boll number/plant was determined by both additive and nonadditive gene actions while average boll weight was mostly controlled by additive gene action. Boll weight could be improved by inter se mating among selected plants in the segregating generations. The line BCS 9–10 and the testers TCS 30-6, TCS 3–5 and TCS 9–5 were high general combiners for yield, boll weight, ginning outturn, lint weight/100 leeds,and earliness. In a 5-location trial, the top yielding hybrids produced 80–100% higher yield than the cultivars and were equal to the commercial hybrid DCH-32.