Effects of drought stress on shoot development of tomato (Solanum lycopersicum L.)

In recent years, drought stress was strongly affected on the development and yield of tomatoes. There are increasing interests in the study of physiological transformations in adaption to stress in plants In this study, effects of drought stress (mannitol at different concentration) on the development of tomato shoot were studied. Morphological and physiological changes during the development of shoot under drought stress conditions were analyzed. Based on the analysis results, the combination of cytokinin and gibberellin was treated to increase the drought stress tolerance of plants. Results showed that mannitol at 20 g/L induced tomato drought stress. Shoot height, number of leaves, leaf area, and the number of roots significantly decreased in the drought stress condition compared to the control. The formation superoxide (O2-) and hydrogen peroxide (H2O2) occurred in the meristem, elongation region and cap of the roots in the drought stress condition instead of only cap root in the control. In the drought stress condition, there was an increase in respiration intensity, proline and carotenoid content, and abscisic acid activity. In contrast, the content of chlorophyll, photosynthesis intensity, cytokinin and gibberellin activity decreased in comparison with the control. The combination treatment of zeatin 0.5 mg/L and GA3 0.5 mg/L improved the drought stress tolerance of plants. The shoot height, number of leaves, leaf area and number of roots of the treated plants were higher than those of the control plants.