Effects of Spraying Abscisic Acid on Photosynthetic Physiology of Lettuce Seedlings under Salt Stress

The glass lettuce was made as material, the effect of different concentrations (0, 1, 5, 10, 20 mu mol.L-1) of exogenous abscisic acid on photosynthetic pigments and photosynthetic characteristics of lettuce seedlings under salt stress was studied. The results showed that when the concentration of abscisic acid was lower than 10 mu mol.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 increasing of abscisic acid concentration. When the concentration of abscisic acid was higher than 10 mu mol.L-1, all indicators decreased. But the opposite trend of intercellular carbon dioxide was presented. Therefore, spraying abscisic acid could increase the resistance of lettuce under salt stress, and the best abscisic acid concentration for lettuce against salt stress was 10 mu mol.L-1.