Genetic Behavior of Yield and its Components of some Rice (Oryza sativa L.) Genotypes under Two Water Irrigation System

This study aimed to estimate the combining ability and heterosis of yield and its components of some rice genotypes (Oryza sativa L.) under two different irrigation systems. Eight genetic diverse parents and 28 hybrids derived from them through the half-diallel mating design. The experiments were conducted at experimental farm of the Rice Research and Training Center, Kafr El Sheikh, Egypt, during 2023 and 2024 rice seasons. The studied traits were; number of panicles per plant, main panicle length, number of grains per panicle, spikelet fertility (%), main panicle weight, 1000-grain weight, number of filled grains per panicle, grain yield per plant and harvest index %. The results showed that the mean squares values for irrigation, genotypes, parents and F1 hybrids were highly significant for all the studied traits in both irrigation treatments and their combined. Crosses mean squares for parents vs crosses as indication to the average heterosis overall crosses were significant for all studied traits under both irrigation treatments and their combined. The best crosses were P1×P6, P2×P6, P2×P8, P3×P4, P3×P6, P3×P8, P5×P7 and P6×P8 for yield and most of its components under both irrigation treatments and the combined data. The parents (Sakha108, PL77-8-7 and Sakha super 302) were the best general combiners for yield and most of its components. The crosses P1×P6, P1×P8, P2×P6, P2×P8, P3×P6, P3×P8, P4×P5, P5×P6 and P6×P8 had high values of mean performance and gave the highest desirable SCA effects in both irrigation treatments and the combined data for grain yield per plant.