Selection Criteria to Assess Drought Stress Tolerance in Wheat Genotypes Using Physiological and Biochemical Parameters

Wheat is an important “rabi” (post-rainy season) crops cultivated on more than 8.0 million hectares in Pakistan. Selection based on different secondary traits enhances the progress and accuracy by which drought tolerant genotypes can be identified. In a glass house experiment, different physical and biochemical characteristics associated with drought adaptation were assessed in twelve (12) wheat genotypes. Drought tolerance index, calculated based on seedling dry weight, exhibited that Pirsabak-2004 was the most drought tolerant genotype. Minimum reduction in dry weight (14.32 %), RWC (14.15 %) and leaf area (5.59%) as well as least increase in H2O2 content (104.9%) was noted in Pirsabak-2004. However, Pirsabak-2008 has suffered minimum reduction in fresh weight (28%) and cellular membranes stability (10.89%). Maximum increase in proline (7.75 fold) and sugar content (163.51 %) was noted in PR-97 and PR-90, respectively. Similarly, Saleem-2000 has incurred the minimum reduction in chlorophyll content (32.27%) under drought stress conditions. Furthermore, correlation coefficient calculated between the dry weight and different parameters exhibited seedlings fresh weight, relative water content, H2O2 concentration and membrane stability (r = 0.654, 0.796, -0.824, 0.812, respectively) as the most important secondary traits for selection of wheat genotypes under drought stress conditions.