Systematic salt tolerance-related physiological mechanisms of wild soybean and their role in the photosynthetic activity and Na distribution of grafted soybean plants.

Systematic salt tolerance-related physiological mechanisms in roots and shoots of halophyte Dongying wild soybean have not yet been thoroughly studied. In this study, photosynthesis, modulated 820-nm reflection, chlorophyll fluorescence, and Na distribution in cultivated ( ) and wild ( ) soybean leaves of grafted soybean plants were investigated after NaCl treatment. Results showed that the decreases in photosynthetic rate, performance index, active P content, and plastocyanin reduction were significantly greater in the leaves than those in the leaves. The observed increases in the Na concentration in the leaves were likely responsible for the severe decrease in the photosynthetic activity of grafted plants. We suggest that Na accumulation in roots, which prevents the transport of Na from the roots to the shoots, effectively maintains the concentration of Na at a comparatively low level in the leaves to prevent the destruction of the photosynthetic apparatus by salt.