Development of Isogenic Restorer Line in Extra Long Staple Cotton Variety Suvin

Cotton is the most important commercial crop of India and heterosis in cotton is well documented with 7 to 50 per cent heterosis in interspecific (G. hirsutum x G. barbadense) hybrids, 10 to 138 per cent in intra-hirsutum hybrids and upto 220 per cent in desi (G. herbaceum x G. arboreum) hybrids. Currently hybrid cotton, especially Bt cotton hybrids, occupies more than 80 per cent of cultivated area under cotton in India. Male sterility system offers tremendous advantage to produce quality hybrid seeds at affordable price so that even marginal farmers can take up hybrid cultivation. In cotton both GMS and CGMS systems are available. In cotton, two types of male sterility viz., Genic (GMS) and Cytoplasmic-Genic (CGMS) systems have been identified. Both the systems have been utilized for the commercial hybrid seed production in India and other countries. In CGMS system, the male parent of the hybrid needs to be converted into Restorer line. In cotton, Suvin is the only extra long staple G. barbadense variety available which is capable of spinning to 120s count yarn. This variety has been successfully converted into Restorer line through back cross breeding utilizing Pima Restorer as the donor parent. Suvin Restorer is found to stably restore fertility in different CMS lines of G. hirsutum. The interspecific hybrids developed using Suvin Restorer was found to combine both high yield and superior fibre quality capable of spinning upto 80s count and are comparable with conventional check hybrids.