INTRASPECIFIC HETEROSIS IN DIPLOID AND TETRAPLOID COTTONS

Abstract

Studies on heterosis were made in diploid (Gossypium a1boreum L.) and tetraploid (G. hirsutum L.) cottons for seed cotton yield over three years. Heterosis over better parent and commercial heterosis ranged from 10.9-98.7% and 40.2-162.2% in diploid and from 7.3-246.2% and 6.9-107% in tetraploid cotton, respectively. In the latter species, heterosis over the popular hybrid ranged from 11-134.4%. The important heterotic aosses were LD 135 x Spotless (162.2%), LD 135 x Naked Seeded (155.7%), and Lohit x Spotless (136.9%) in diploid; and DCI 118c x F414 (107.7%), Tamcot Camde x MCU10.(97.7%), and MCU10 x H 777 (89.6%) in tetraploid cotton. A close relationship between the yield of parental lines andtheirhybrids was observed. The geneticbase and geographical diversity of the parental lines were also associated with the manifestation of heterosis. Ample scope for evolving high yielding intra-hirsutum hybrids but limited scope for intra-arboreum hybrids was indicated.