Performance and Genotypic Variability of Three Bread Wheat Cultivars under Stress Irrigation Regimes

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WO FIELD experiments were conducted at the experimental farm of Faculty of Agriculture, Kafrelsheikh University, Egypt during 2011/2012 and 2012/2013 seasons. The main objective of this investigation was to study the influence of three levels of drought stress imposed during critical stages on the performance and genotypic variability of three bread wheat cultivars. Results indicated that exposure wheat plants to moderate (two irrigations) or high stress (only one irrigation) decreased significantly all characters (except spike length) compared with low drought stress (three irrigations). However, the differences between moderate and high drought stress were not significant for No. of spikelets/ spike and No. of grains/ spike. Large variations among wheat cultivars were recorded for all the studied characters, indicating that wide range of genetic variability were present among the studied cultivars. As average over stress regimes, Sids 12 recorded the most desirable values for spike length, No. of spikelets/ spike, No. of grains/ spike, spike weight and grain yield. Whereas, the differences between Sids 12 and Misr 1 were not significant for grain yield. Misr 1 gave the highest values of plant height, heading date, No. of spikes/ m² and 1000-grain weight. Heading date, plant height, spikes/ m², 1000-grain weight and grain yield were significantly affected by the interaction between irrigation regimes and wheat cultivars. The highest grain yield was recorded for both Misr 1 and Sids 12 wheat cultivars under low irrigation stress (0.62 and 0.59 kg/ m², respectively). However, the differences between moderate and high stress were not significant (for grain yield) in case of Giza 168. Correlation analysis of yield and yield related characters indicated that under low drought stress condition, No of spikes/ m² and 1000-grain weight was positively correlated with grain yield. While, these traits were spike length, No. of spikelets/ spike, No. of grains/ spike and spike weight in case high drought stress conditions. The extent of coefficient of variation indicated that high estimates of phenotypic (PCV) and genotypic (GCV) coefficients of variability were exhibited by number of grains/ spike (23.7 and 22.3), number of spikes/ m² (26.1 and 24.14), spike weight (26.5 and 24.2) for PCV and GCV, respectively.