Abstract

Information on the genetics of fertility restoration facilitates breeding and/or selection of restorer lines used in hybrid breeding program in a cytoplasmic male sterility (CMS) system. Inheritance of fertility restoration of WA type CMS in rice, (Oryza sativa L.) was studied utilizing IR58025A, IR62829A and IR68899A CMS lines and three restorers viz., Amol-2, IR50 and Poya. The F1s showed pollen and spikelet fertility similar to the restorer parents, indicating that restoration ability were dominant and the cytoplasmic-genetic sterility system of CMS lines were sporophytic in nature. Evaluation of fertility in F2 populations and testcross progenies (BC1) revealed that fertility restoration in Amol-2 and IR50 were controlled by two major dominant genes whereas, it was controlled by one dominant gene in Poya. Segregation for spikelet fertility in F2 and backcross generation conformed to the results on pollen fertility. Analysis of line x tester indicated pre-dominance of non-additive genetic variance. It suggested greater importance of non-additive gene action in pollen and spikelet fertility expression and indicated very good prospect for the exploitation of non-additive genetic variation for pollen and spikelet fertility through hybrid breeding.

Key words: Rice, genetics, male fertility restoration, combining ability.

Abbreviation

CMS, Cytoplasmic male sterility; Rfs, restorer alleles; GCA,general combining ability; F, fertile; PF, partially fertile; PS, partially sterile; CS,completely sterile.