Possible mechanism of inhibition on photosynthesis of Lycium barbarum under salt stress

Using different concentrations of salt treating Lycium barbarum seedlings, the photosynthetic rate and other physiological indexes of leaves were measured at different growth stages. The results showed that under salt stress, the photosynthetic rate,stomatal conductance,chlorophyll content and chlorophyll fluorescence kinetics parameters Fm, Fv, Fm/Fo, Fv/Fo and Fv/Fm of leaves decreased, while the soluble carbohydrate and polysaccharides of Lycium barbarum increased. The intercellular CO 2 concentration showed a trend from decrease to increase, but the Ls increased at first, and then decreased. Changes of the Ci and Ls showed that the decline of photosynthetic rate of Lycium barbraum was mainly caused by temporary stomatal limitations.In the long run, in long time, it was caused by nonstomatal limitations.Changes of other physiological indexes and significant correlations between them and Pn showed that the multiple reactions of these physiologic characteristics determined the photosynthesis declination of Lycium barbarum under salt stress. The results also indicated that the photosynthesis of Lycium barbarum was inhibited insignificantly under the soil salt content below 0.5%, which suggested that there were certain salt tolerance of Lycium barbarum.