Abstract: In this paper, the effects of NO donor sodium nitroprusside (SNP) on the chlorophyll fluorescence and antioxidant system of Dendrobium huoshanense under high light stress were studied. The result showed that the efficiency of light energy conversion and nonphotochemical dissipation of excess light energy for photosystemⅡ were inproved, and the capacity of scavenging active oxygen for antioxidant system was increased as well by presoaking with 0.1 mmol·L^-1SNP , which alleviated the photoinhibition on leaves of Dendrobium huoshanense significantly. Therefore the PSⅡ was protected efficiently and the recovery was faster. On the contrary, the leaves presoaked in 0.5 mmol·L^-1SNP were severely inhibited by the high light and the enzyme activities of SOD, POD and CAT were decreased.

Key words: Dendrobium huoshanense, NO, high light stress, PSⅡ