Hybrid inviability and weakness in certain indica rice crosses

Abstract

The existence of a partial reproductive isolation in the form of hybrid inviability and weakness supplemented by hybrid sterility was evident in four crosses of PTB 7 with PTB 10 and CO 29. F: plants were inviable or weak and were characterised by stunted growth, less tillering, late flowering and high spikelet sterility. Selfed progenies of weak Fj plants showed segregation for weak and inviable and normal plants in definite ratios. However, hybrids between PTB 10 and CO 29 were normal. The lethality and weakness of plants in fl and later generations were found to be determined by the action of a pair of complementary dominant lethal genes, one of which was present in PTB 7 and the other present commonly in both PTB 10 and CO 29.