Estimation of combining ability and heterosis for grain yield, yield components, and some grain quality traits in rice under water deficit conditions

Abstract

Combining ability analysis was carried out in rice through an 8 x 8 diallel set analysis excluding reciprocals involving 8 diverse parents for grain yield, yield components, and some grain quality traits at the Experimental Farm of the Rice Research Department, Sakha, Kafr El-Sheikh, Egypt, during the 2020 and 2021 summer seasons. The ratio of variances due to general and specific combining abilities (ó2 GCA / ó2 SCA) was less than unity for all the studied traits under water deficit and normal conditions, indicating that the non-additive type of gene action, including dominance, was of great importance in the inheritance of these traits, except that the hulling percentage under normal conditions was higher than unity. Among the parents, IET 1444 and Nerica 9 were found to be significantly superior general combiners for grain yield/plant. The parents IET 1444 and Sakha Super 300 were good general combiners for number of panicles/plants, number of filled grains/panicle and fertility (%). While IET 1444 and Nerica 9 were good general combiners for panicle length and grain yield/plant, Moreover, IR 65600-77 and Nerica 9 were the best general combiners for 100-grain weight. On the other hand, Sakha 109 and IET 1444 were good combiners for earliness. Sakha 108 and Sakha 109 were good combiners for plant height. The rice variety IR 69116 was a good general combiner for grain length and grain shape. while IR 65600-77 was a good combiner for amylose content (%). In addition, a total of 11 crosses exhibited positive significant and highly significant SCA for grain yield/plant. The promising combinations for grain yield and most of the studied traits were IR 69116 ×