Abstract: Salinity tolerance rating (STR), relative dry weight of shoot(RDWS), relative plant height (RPH) and Na⁺/K⁺ in root of 20 rice cultivars were examined at 3- to 4-leaf stage aquacultured with different NaCl concentrations for 10 days. Results indicated that large variability of STR and Na⁺/K⁺ in root among 20 cultivars occurred under 0.5% NaCl stress, while that of RDWS and RPH appeared under 0.8% NaCl stress. It suggested that these two NaCl concentrations were appropriate for differentiating the salt tolerance of rice seedlings. Based on the results of the four indexes, Jiucaiqing, Norin 72, 80-85, Dongtingwanxian and Dingxuedao were classified into strong salt-tolerant cultivars, and Pokkali, IR26, Xiaobaimangdao, Mengwanggu and Minghui 63 were medium salt-tolerant. Furthermore, eight cultivars were selected to identify the salt tolerance of rice at 3- to 4-leaf stage under three different temperatures. It was found that the Na⁺/K⁺ in root and STR were a little different among evaluated cultivars at the low temperature (23±3℃/15±1℃, day/night), but they were aggravated with the death of some cultivars at the high temperature(36±1℃/26±2℃, day/night). Only in the relatively mild temperature(30±2℃/24±2℃, day/night), there was the most significant difference in the Na⁺/K⁺ in root and STR among evaluated cultivars, so it was considered that the relatively mild temperature was proper temperature to screen salt tolerance of rice cultivars.

Key words: rice, salt tolerance, screening method, identification index

摘要： 在水培条件下，用5种不同浓度的NaCl溶液对20个水稻品种的3~4叶期幼苗进行盐胁迫处理，10 d后考查不同品种单株盐害级别、苗高、茎叶干重和根系Na[sup]+[/sup]/K[sup]+[/sup]含量比等性状。结果表明，0.5%的NaCl胁迫下，品种间的盐害级别和根系Na[sup]+[/sup]/K[sup]+[/sup]含量比差异最大；0.8%的NaCl胁迫下，品种间的相对苗高和相对茎叶干重差异最大。其中韭菜青、农林72、8085、洞庭晚籼和丁旭稻为强耐盐水稻品种；Pokkali、IR26、小白芒、勐旺谷、明恢63为耐盐或中度耐盐品种。进一步选择8个耐盐性不同的水稻品种，在3种温度条件下进行苗期耐盐性鉴定，发现在相对低温[昼/夜为(23±3)℃/(15±1)℃\]时，水稻生长缓慢，不同品种的盐害级别和根系Na[sup]+[/sup]/K[sup]+[/sup]含量比均较低；在温度较高[昼/夜为(36±1)℃/(26±2)℃\]时，水稻生长加快，不同品种的盐害级别和根系Na[sup]+[/sup]/K[sup]+[/sup]含量比均增高；只有在适温条件[昼/夜为(30±2)℃/(24±2)℃\]下，水稻生长较快，品种间的盐害级别和根系Na[sup]+[/sup]/K[sup]+[/sup]含量比差别最明显。提出在适温条件下，以0.5%或0.8%的NaCl浓度进行水稻品种耐盐性的筛选和耐盐特性的遗传研究比较合适。

关键词: 水稻, 耐盐性, 鉴定方法, 鉴定指标