Drought Stress Effects on Plant Water Relations, Growth, Fruit Quality and Osmotic Adjustment of Tomato (Solanum lycopersicum) under Subtropical Condition

The pot experiments were conducted in 2 subsequent years in the net house of the Dept. of Soil, Water and Environment, Dhaka University to evaluate the effect of water stress on the growth, plant water relations, fruit quality and osmotic adjustment of seven tomato cultivars. The percentage of field capacity levels were 40, 70 and 100. The tomato plants subjected to water stress during their growth period had decreased relative water content (RWC) of leaves and moisture content in tomatoes compared with the plants supplied with adequate moisture. Water use efficiency (WUE) also decreased with increasing moisture stress. A significant increase in organic solutes, glucose (85%), fructose (62%), sucrose (121%) and proline (103%) at 40% F.C. compared with 100% F.C. showed a tendency of these plants to adjust osmotically. Ascorbic acid, citric acid and malic acid were also significantly enhanced by water stress treatments. The quality of fruits was improved as a result of the synthesis of these acids.

Water stress did not affect the height of plants and no physical damage due to stress was observed in fruits and were over 90% red. Ripening and fruit quality showed that none of the stress-treated tomatoes deteriorated in quality. On the other hand, water stress enhanced the sweetness of the tomatoes by increasing their glucose, fructose, and sucrose contents and improved the quality by increasing the amount of important acids such as ascorbic acid, malic acid and citric acid.