| Soil salinity is recognized as one of the major abiotic stresses negetively affecting crop productivity worldwide. In this study, 60 japonica rice varieties were grown in IRRI standard nutrient solution, in which 125 mmol/L NaCl was added 14 days after germination. In the third and sixth days after salt stress treatment, the leaf damage percentage and MDA content were measured. The visual foliar symptom was used to evaluate the scale of the salt tolerance at the sixth day after salt treatment, and then plant height, shoot fresh and dry weight, root fresh and dry weight were measured. The results showed that the leaf damage percentage, MDA content and other physiological traits were significantly negatively correlated with salt tolerance score. The relative fresh and dry weight of the tolerant cultivars were significantly higher than those of the sensitive cultivars, while the leaf damage percentage and leaf MDA content measured after stress for six days of the tolerant cultivars were significantly lower than those of the sensitive cultivars. According to the salt tolerance score, these 60 japonica rice varieties were divided into three groups. The MDA content of leaves measured after stress for three days had no significantly differance among these 3 groups. The leaf damage percentage and leaf MDA content measured after stress for six days of salt tolerance group (T) were significantly lower than the saltsensitive group (S) and intermediate group (M) and there was no overlap in the distribution range between those of saltsensitive group and salt tolerance group. The results indicated that the leaf damage percentage and leaf MDA content measured after stress for six days could be used for the evaluation of salt tolerance in cultivated rice at the seedling stage.Therefore, the method of evaluating salt tolerant rice cultivars at the seedling stage by these two physiological traits in hydroponics will be used in germplasm identification, gene cloning and cultivar development of salt tolerance in rice. |
