Effects of thermal pretreatment on the germination and growth of tomato (Solanum lycopersicum L.) under drought stress

In this study, effects of thermal pretreatment on tomato seed germination and the plant development in drought stress conditions were studied. Morphological, physiological and biochemical changes during the growth of tomato seedling were analyzed. Germination of tomato seeds was divided into three stages: water uptake, water saturation, and germination. Our experiments showed that mannitol at the concentration of 35 g/L induced drought stress. In drough stress condition, germination rate and radicle length were significantly decreased to approximately 50 %; and the thermal pretreatment (45°C) of seeds at the end of water saturation for 120 minutes helped in improving germination rate, the radicle differentiation, hypocotyl length and leaf numbers. Recovery effects of thermal pretreatment on seed germination and plant growth under drough stress coincided with the increase in respiratory rate, total sugar, protein, proline contents, and especially the content of IAA. In addition, our thermal pretreatment could also help to increase the number of flowers of studied plants.