Author(s):

Anoj Kumar Kuwer, Dilip Kumar Pandey, Sanjay Kumar Ram and VK Sharma

Abstract: To elucidate the nature and extent of differentiation in maintainers and restorers of cytoplasmic male sterility system in rice and to investigate the indica and japonica type divergence of breeding lines. The experimental materials comprised of ten restorers and ten maintainers of wild abortive cytosterility system and two checks from indica and japonica backgrounds. The observations on apiculus hair length, germination speed, degree of resistance to low temperature and potassium chlorate, absorbance of phenol solution after soaking grains, phenol reaction of grain surface, localisation of phenoloxidation system and peroxidase isozymes pattern were recorded to ascertain the nature and extent of differentiation and divergence. Three replications were made for the former five characters. The inference was derived precisely with the help of mean squares, mean values, range, critical difference, taxonomic distance and similarity coefficient based dendrogram and peroxidase zymogram. Maintainers showed relatively greater range of variation for germination speed, degree of resistance to low temperature and potassium chlorate, same range of variation was noticed in maintainer restorers for the apiculus hair length and absorbance of phenol solution after soaking grains. Predominance of indica check like combination of short apiculus hairs, positive phenol reaction and greater degree of low temperature and potassium chlorate resistance was noticed in restorers. Five restorers while one maintainer exhibited indica check like characters combination. Promising restorers and maintainers should be produced separately by inter-crossing and subsequent selection in the course of their improvement where one pool of inter-crossing should be for restorers and another for maintainers. The findings of this study implied that the pools of promising restorers and maintainers should be produced separately by inter-crossing and subsequent selection in the course of their improvement where one pool of inter-crossing should be for restorers and another for maintainers. In this way, the genetic diversity retained between these two groups of breeding lines should provide for an enhanced level of heterosis when utilised in breeding programmes.

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