Performance and Combining Ability of Some Agronomic Traits of Bread Wheat Under Normal and Water Stress Conditions

Abstract

The present investigation was carried out during 2015/2016 and 2016/2017 seasons at the Experimental Research Station, Faculty of Agriculture, Assiut University. The objectives of this investigation were to obtain information about the performance and genetic components of parental wheat genotypes and their F1s under normal and water stress conditions. The performance of all genotypes under water stress condition was lower than its performance under normal condition. The parent 6 (P6) was the earliest flowering under both conditions and the parent P5 under water stress condition (85.70 day), while the parents P1, P2,P4 andP6 gave the tallest spike under both of normal and water stress conditions. While, P1 and P2 gave the tallest spike under water stress condition. The hybrids (P4 × P5) and (P1 × P6) were the earliest among F1- hybrids under normal and water stress conditions, respectively. Furthermore, the hybrids (P1 × P3) and (P1× P4) gave the tallest spike under normal and water stress conditions, respectively. The mean of grain yield /plant for all genotypes was 32.70 g and 24.96 g under normal and water stress condition, respectively. The P6 gave the highest grain yield/ plant compared with other parental genotypes under both conditions. On the other hand, the highest grain yield /plant was obtained from the hybrids (P4 × P5) under both conditions. The results showed that the magnitude of SCA exceeded GCA ones for days from planting to 50 % heading trait, which indicating that the major portion of genetic variance was due to the non-additive gene effects. The ratio of GCA/SCA was noticed to be low for days from planting to 50 % heading trait, indicated the specific combining ability was more important than general combining ability variance. The ratio of GCA/SCA was low for Plant height except SCA under irrigation in the F1- hybrids. The ratio of GCA/SCA was 1.08 and 0.80 in the F1-hybrids under normal and water stress conditions, respectively. The good genotypes for plant height in the F1- hybrid under both environments were Entry 21 and Entry 20. While, the ratio of GCA/SCA was noticed to be low for spike length, indicated the specific combining ability was more important than general combining ability variance, which indicating that the major portion of genetic variance was due to the non-additive gene effects. The results showed that the magnitude GCA/SCA ratio for number of kernel/spike was 0.31 and 0.20 in the F1-hybrids under normal and water stress conditions, respectively, indicating that the non-additive were larger than additive effects in the inheritance of number of kernel/spike and both were highly significant. The ratios of GCA/SCA were less than the unity for grain yield/plant under both environments indicating that the non-additive gene action controlled the inheritance of grain yield/plant. The GCA/SCA ratio was 0.14 and 0.48 for 100-grain weight in the F1-hybrids under normal and water stress conditions, respectively, indicating predominance of non-additive gene effect in the inheritance of 100- grain weight