Pakistan Journal of Biological Sciences 1028-8880 1812-5735 Asian Network for Scientific Information 10.3923/pjbs.2000.652.656 Subhani Ghulam Mahboob Chowdhry Muhammad Aslam Gilani Syed Mansur Mohsin 4 2000 3 4 Thirty-six genotypes of bread wheat (Triticum aestivum L.) were evaluated for genetic variability parameters and regression analysis under irrigated and drought stress conditions. Tillers per plant, peduncle length, 1000-grain weight, grain weight of mother shoot, biomass per plant and grain yield per plant exhibited high genotypic coefficient of variability under both environments. Grain yield per plant suffered a maximum reduction of 68 percent followed by 58.9, 57.4, 42.7, 41.5 and 27.4 percent, for biomass per plant, flag leaf area, tillers per plant, grain weight of mother shoot and plant height under drought stress conditions compared to irrigated conditions, respectively. High heritability estimates 90.08, 85.01, 83.32, 76.01, 74.86 and 72.23 percent were found for 1000-grain weight, days to heading, peduncle length, spike length, plant height and spikelets per spike, respectively under irrigated conditions. High values of heritability were shown for days to heading, 1000-grain weight and spike length under drought stress conditions. Regression analysis indicated the importance of biomass per plant, harvest index and tillers per plant in influencing grain yield per plant in bread wheat. The plant height is more important than grain weight of mother shoot in case of drought stress conditions for the contribution of grain yield per plant.

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