Impact of Antioxidant Enzymes and Physiological Indices as Selection Criteria for Drought Tolerance in Sesame Populations

In this study, we sought to determine whether the increases in peroxidase (POX), catalase activities (CAT), normalized differential vegetation index (NDVI), chlorophyll pigments as (SPAD reading), proline and relative water content (RWC) as selection criteria for drought tolerance in sesame and how to improve water use efficiency (WUE) under drought stress. Four sesame populations were derived from crossing among six parents i.e., population 1 (Sandaweel 3* 375* Sandaweel 3), population 2 (Lines 237*217* 241), population 3 (Sandaweel 3* lines 241* 237) and population 4 (Lines 241* 217* 220) for two growing seasons. Measurements were taken under various of water deficit levels (100 % ETo, 80 % ETo, 60 % ETo). The highest seed yield was belonging to population No.4 while, population No.1 and 3 were the lowest among populations. The NDVI index was sensitive to changes in plant biomass, vigor, and leaf size, which varies from water deficit level to another and from population to another. The activities of peroxidase and catalase antioxidant enzymes were altered when plants were subjected to stress. POX and CAT activity increased significantly in all populations for both drought stress Levels. CAT activity increased in Pop. No.4 more than 20 folds due to water stress. Results suggest that water deficit induces oxidative stress in growing sesame plants and that peroxidase and catalase could serve as important components of antioxidative defense mechanism against drought. Proline, RWC, chlorophyll content and NDVI are powerful tools for the study of spatial and temporal heterogeneity of leaf transpiration and photosynthetic performance. The highest values of WUE of seed or oil yields (kg/m3) were obtained by irrigating population 4 under sever water stress. The correlations between NDVI and grain yield within individual trials varied depending on crop stage, moisture availability, and genotypes composition. The genotypes were accumulated more proline due to stress had the same genotypes which gave the highest RWC, POX and CAT enzymes.