Abstract: A hydroponic experiment was conducted to investigate the physiological mechanism of safflower (Carthamus tinctorius) in response to salt stress. Four treatments with various salt concentrations (0, 50, 100 and 150 mmol·L^-1 NaCl) were employed and arranged by a completely randomized design with three replications. The results showed that the growth of safflower seedlings was significantly inhibited with the increasing salinity of hydroponic solution, while the effect of salt stress on the roots was less than that on the aerial parts. After a duration of 10 days salt stress, the SOD activity in safflower leaves under salt stress was significantly increased as compared with CK; however, TAOC activity remained unchanged. The contents of soluble protein and sugar among the salt treatments were not significantly different, but significantly increased in comparison with CK. When the safflower was saltstressed for 20 days, the SOD activity in leaves remained unchanged, but the CAT and T-AOC activities increased greatly as compared with CK. Also, the soluble sugar and protein contents greatly increased with increasing the salinity of hydroponic solutions. At 30 days of salt stress, the soluble sugar and protein were markedly accumulated in leaves of safflower. The activities of T-AOC and SOD were significantly decreased as compared with that of CK, while the CAT activity remained unchanged. Therefore, the safflower withstood the salt stress mainly through increasing the levels of osmoregulation substances and active oxygen scavenging capacity at the seedling stage, and the inductive increase of soluble sugar might play a key role.

Key words: pollen, abiotic stress, floret sterility, rice