Maize (Zea mays L.) is the third most important cereal grain in Egypt (after wheat and rice) but it is vulnerable to water stress which causes lead losses in both yield and quality. In the current study we evaluated 100 S1-lines along with their top-crosses using two testers under normal and water stress conditions. We used line × tester to assess general (GCA) and specific (SCA) combining ability effects for 100-grain weight and grain yield per plot; In addition, we estimated heritability for both traits. Result of line × tester analysis showed highly significant differences among parents, crosses vs parents., In addition, between testers and lines × testers for both traits under normal and water stress condition. The results, lines showed non-significant for 100-grain weight under normal and water stress condition. Grain yield per plot showed non-significant differences under normal condition while it showed significant under water stress condition. Under normal condition, S1-lines 56 and 88 possessed the highest 100-grain weight while, the highest values of 100-grain weight were found in cross combinations including S1-line 29 × SC162 and S1-line 61× TWC352. On the other hand, S1-lines 65 and 68 possessed the highest grain yield per plot while, the highest values of grain yield per plot were found in cross combinations including S1-line 86 × SC162 and S1-line 37× TWC352. Under normal condition, S1-lines 10 and 99 displayed positive and significant GCA effects for 100-grain weight while, S1-line 86 and 55 exhibited the maximum GCA effect for grain yield per plot. Top-crosses including S1-line 29×SC162 and S1-line 75×TWC352 were good specific combiners for 100-grain weight while, the top-crosses including S1-line 29×SC162 and S1-line 78×TWC352 were good specific combiners for grain yield per plot. Heritability in broad sense showed moderate highly estimates for both traits. Our results indicated the preponderance of dominance gene action in controlling both aforementioned traits. In conclusion, these S1-lines are promising to produce drought tolerant inbred line in the future, which may lead to produce drought tolerant hybrid.
The present article was carried out to study the relative merits of pedigree selection for grain yield/plant under drought stress and normal irrigation environments. Three cycles of pedigree
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 F 1 s 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 (P 6 ) was the earliest flowering under both conditions and the parent P 5 under water stress condition (85.70 day), while the parents P 1 , P 2 , P 4 and P 6 gave the tallest spike under both of normal and water stress conditions. While, P 1 and P 2 gave the tallest spike under water stress condition. The hybrids (P 4 × P 5 ) and (P 1 × P 6 ) were the earliest among F 1 -hybrids under normal and water stress conditions, respectively. Furthermore, the hybrids (P 1 × P 3 ) and (P 1 × P 4 ) 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 P 6 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 (P 4 × P 5 ) 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
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