Effects of Exogenous Melatonin on Photosynthetic Physiology of Lettuce Seedlings under Salt Stress

摘要

The glass lettuce was made as material, the effect of different concentrations (0, 50, 100, 150, 200 μmol·L~(-1)) of exogenous melatonin on photosynthetic pigments and photosynthetic characteristics of lettuce seedlings under salt stress was studied. The results showed that when the concentration of melatonin was less than 100 μmol·L~(-1), the chlorophyll content, carotenoid content, net photosynthetic rate, stomatal conductance, and transpiration rate in leaves of lettuce seedlings were all increased along with the increased of melatonin concentration. When the concentration of melatonin continued to increase, all indicators decreased. But the opposite trend of intercellular carbon dioxide was presented. Therefore, spraying melatonin could increase the resistance of lettuce under salt stress, and the best effect was obtained when the concentration was 100 μmol·L~(-1).