Effect of NaCl stress on the physiological and biochemical characteristics of Citrus grandis ‘Pingshanyou’ seedlings under hydroponic culture condition

Effects of different concentrations of NaCl on the physiological and biochemical characteristics of Citrus grandis ‘Pingshanyou’ seedlings were studied by using hydroponic culture method. The results showed that the macromolecule leakage value and malondialdedyed (MDA) content in leaves of the seedlings increased significantly, but the relative water content (RWC) decreased obviously when treated by 120 mmol·L -1 NaCl for 10 d or 80 mmol·L -1 NaCl for 20 d. It had no effect on amino acid content, pH value of cell sap and root vitality of the seedlings stressed by 120 mmol·L -1 NaCl for 10 d, but the root vitality decreased obviously under 40 mmol·L -1 NaCl stress for 20 d, the amino acid content and the pH value of cell sap in leaves did not change significantly until treated by 80 or 120mmol·L -1 NaCl for 20 d, respectively. Therefore, it might be suggested that the root system of C. grandis ‘Pingshanyou’seedling is more sensitive to NaCl stress. The contents of photosynthetic pigments in leaves of the seedlings decreased when stressed by different concentrations of NaCl for 30 d, the decreasing of contents of chlorophyll b and carotenoid were obviously, so photosynthetic pigments are sensitive to NaCl stress.