Effects of Exogenous Melatonin on Photosynthetic Characteristics of Eggplant (Solanum melongena L.) under Cadmium Stress

A pot experiment was conducted to study the effects of exogenous melatonin (MT) on photosynthetic characteristics of eggplant under cadmium (Cd) stress. Five treatments were used in the experiment: leaves were sprayed with 0 (CK), 25, 50, 100 and 150 μmol·L -1 concentrations of melatonin solution. The results showed that melatonin enhanced net photosynthetic rate (Pn) and transpiration rate (Tr) of eggplant significantly. With the increasing of melatonin concentration, photosynthetic capacities of eggplant seedlings were enhanced. The result of light use efficiency (LUE), stomatal conductance (Gs) and CO2 concentration of intercellular (Ci) were the same as Pn. Spraying melatonin decreased WUE of eggplant. Therefore, melatonin could use to enhance the photosynthetic ability of eggplant, which would help to improve the adaptability of eggplant, and the best concentration of melatonin was 150 μmol·L -1 .