Abstract: The salt-tolerant (Qiangfeng 7301) and salt-sensitive (Qiuyan) pepper varieties were selected to study chlorophyll fluorescence parameters as well as other related indexes change of pepper seedlings under NaCl stress with the concentrations of 50, 100, 150, 200, and 250 mmol·L^-1, respectively, and no NaCl was set as control (CK) in this experiment. The results showed that salt stress decreased the Ф_PSⅡ, ETR, F_v/F_m, qP and increased qN, F_o, electrolyte leakage rate of the two pepper varieties. The content of chlorophyll and soluble protein in the two varieties of pepper seedlings increased under NaCl concentration (0-100 mmol·L^-1), but decreased significantly under NaCl concentration (150-250 mmol·L^-1) with the concentrations of salt stress increased, soluble sugar content of Qiuyan showed a gradually increasing trend on the 5th and 10th day and increased firvstly and then decreased on the 15th and 20th day. However, Qiangfeng 7301 on the 20th day increased firstly and then reduced, and showed gradually rising trend at other treatment time. It indicated that low concentrations of NaCl (0-100 mmol·L^-1) had no significant effect on pepper, while high concentrations of NaCl (150-200 mmol·L^-1) had great influences on pepper seedlings. In addition, it was found that Qiangfeng 7301 showed better salt tolerance than Qiuyan. The results showed that salt tolerance of pepper had better salt tolerance, and the salt tolerance of pepper seedlings was closely related to salt concentrations and stress time.

Key words: pepper, salt stress, chlorophyll fluorescence, physiological properties