A half diallel cross among eight parents of wheat (Triticum aestivum L.) was evaluated
under recommended irrigation and drought stress in RCBD with three replications. Mean
squares for genotypes, parents, crosses and parent vs. crosses were significant for the most
measurements in both irrigation treatments as well as the combined analysis. The highest
mean values were detected under stress condition and combined analysis by parents P4, P6,
P8, P7, P1 and P8 for stomatal conductance (SC), net photosynthesis rate (Pn), protein
percentage, ash percentage, carbohydrate percentage and grain yield/plant, respectively.
Meanwhile, the highest mean values were recorded under stress condition and combined
analysis with crosses P1 x P6, P5 x P8, P3 x P4, P3 x P4 and P2 x P5 for stomatal conductance
(SC), net photosynthesis rate (Pn), protein percentage, ash percentage, carbohydrate
percentage and grain yield/plant, respectively. Superiority percentage relative to check
variety Sahel 1 for grain yield/plant was obtained by crosses; P2 x P5, P2 x P4, P2 x P7, P1 x
P3, P3 x P6 and P5 x P7 under normal and stress irrigations and for the combined analysis.
The mean squares were significant for the most measurements in both irrigation treatments
as well as the combined analysis for general combining ability (GCA) and specific combing
ability (SCA). GCA/SCA ratio, which exceeded the unity was obtained for LT, protein
percentage, carbohydrate percentage, ash percentage and grain yield/plant in both
irrigations treatments and the combined analysis. For chemical measurements (protein,
carbohydrate and ash percentages) and grain yield/plant the ratio of SCA x I/SCA was much
higher than the ratios of GCA x I/GCA. The parental lines P1, P2 and P3 for SC and P5, P6
and P7 for grain yield/plant, exhibited significant positive "
i
g ˆ
" effects under stress
irrigation treatment. The most desirable "
ij S
^
" effects were recorded by the cross P3 x P4
under stress irrigation for LT, TR, Pn and carbohydrate percentage, P1 x P5 and P4 x Gem.9
in the combined analysis for stomatal conductance; P4 x P5 and P5 x P8 under normal, stress
irrigation treatments and the combined analysis for protein percentage.
Key words: Triticum aectivum, General combining ability (GCA), Specific combining ability
(SCA), Heterosis, Drought, Wheat, Randomized Complete Block Design(RCBD) . |
