The effects of drought on physiology of Tomato (Lycopersicon esculentum Mill.) cv., Farida grown in pots
were studied. Drought stress was done by irrigating the plants with 80, 60 and 40% of water needed to reach soil pot
capacity. Nutrients concentrations of the studied tomatoes grown in pots under different irrigation treatments varied
according to water stress levels. The effect of water stress treatments on total chlorophyll, chlorophyll a, chlorophyll b
and carotenoids resulted in significant increase with treatment 80% water deficit, then significant decrease in
accumulation of pigments in response to water stress under 40 and 60% water deficit. All water stress treatments had
highly significant effect on increasing accumulation of proline content. Drought stress induced different changes in the
anti-oxidative enzyme activities, whereas, Ascorpate peroxidase and Catalase increased significantly with water stress
from 0.58 and 140.7 Ug−1 FW in control to 4.08 and 414.9 Ug−1 FW in T4, respectively. In contrary, superoxide
dismutase decreased significantly with water stress from 42.36 in T1, to 31.32, 33.54 and 31.51 in T2, T3 and T4,
respectively. The results indicate that irrigation treatment with 80% of pot capacity (T2) was more effective than T3 and
T4 from the viewpoint of more efficient water use, which would help to minimize drought damage and keep healthy
plants in the same time saving irrigation water by 20%.