Breeding Hybrid Cotton

Abstract

Heterosis refers to the superiority of F1 hybrid in one or more characters over the parental values. In current stage, heterosis and hybrid vigour are used as synonyms and interchangeable. Generally, positive heterosis is considered desirable, but for some characters negative heterosis is also desirable. In cotton, negative heterosis for plant height, micronaire value, maturity duration and gossypol content is desirable because it shows superiority over the parents. The ture heterosis differs from pseudo-heterosis (luxuriance). In case of heterosis, there is increase in general vigour, yield and adaptation. In case of pseudo-heterosis, the F1 exhibits increase in vegetative growth but not in yield and adaptation. Various factors that help in commercial exploitation of heterosis include (1) enough magnitude of heterosis, (2) high percentage of natural out crossing, (3) flower biology, and (4) availability of male sterility system.