Document Type : Original Article
In this study the effects of drought stress on proline, protein, chlorophyll a/b, ascorbate and dehrydroascorbate were investigated in Akri and Mobil cultivars of tomato species. The seeds were cultured at 23 °C with 15-16 hours light period and irrigation was done based on field capacity control (FC), mild drought stress (⅔ FC) and severe drought stress (⅓ FC) under greenhouse conditions. After nine weeks of sowing, leaf, stem and root were isolated and studied for various indices. The results indicated that amount of proline increased significantly in mild and severe stresses in root, but in stem and leaf proline increased only under severe drought stress. Chlorophyll a and b and total protein decreased significantly in mild and severe stress in leaf, stem and root. Ascorbic acid (ASC) increased but dehydro ascorbate decreased significantly in both species. It could be concluded that in both cultivars proline and ASC content increased under severe and mild drought stress although soluble protein and chlorophyll a/b decreased under severe stress. Therefore, in tomato plants osmolyte such as proline and also ASC as an antioxidant compound increased against drought stress. Protein accumulation has protecting role under mild stress.