Identification of elite parents and study of heterosis for important yield traits in rice

Combining ability and heterosis in rice

Abstract

A study was conducted at 20 hybrid combinations derived from Line x Tester (5x4) mating design to estimate the combining ability and heterosis in rice for important yield and its attributing traits. It revealed that there is significant variability present among parents and different cross combinations for majority of the traits studied. The contribution of lines towards the total variance was maximum for days to maturity, panicle length, Specific Leaf Area (SLA) at 80 DAT, Specific Leaf Weight (SLW) at 80 Days After Transplating (DAT) and shoot dry weight. While contribution of testers alone towards the total variance was maximum for Leaf Area Density (LAD) at 60-80 DAT, root dry weight and root shoot ratio. The General Combing Ability (GCA) and Specific Combining Ability (SCA) variances revealed that predominance of both additive and non-additive gene action for different traits and they can be improved either by population improvement methods or by different heterosis breeding methods. JGL 11118 among lines and IR 64 among testers recorded significant GCA effects in desirable direction for majority of the traits. Out of twenty cross combinations studied for heterosis, the crosses viz., BPT 5204 x IR 36 and JGL 11118 x IR 36 and RNR 2465 x IR 64 recorded highest significant positive heterosis for grain yield. Though the perse performance of the parents involved in the heterotic crosses are low, the crosses are heterotic for yield indicating better nicking ability of the parents involved in producing a high heterotic hybrid.