Response of three Glycine species to salt stress

Responses of leaf area, biomass, photosynthetic gas exchange and ion contents to four NaCl treatments, 0, 17, 51, and 85 mM NaCl, were examined for three wild soybean species (Glycine soja, Glycine tomentella and Glycine tabacina). In G. soja, NaCl treatment for 2 months reduced the photosaturated photosynthetic rate (Amax), leaf area and biomass of NaCl treated plants relative to control treatments. Reductions were larger at higher NaCl concentrations. Similar changes were found in G. tabacina, however, the reductions were less than those in G. soja. In G. tomentella, significant reductions in Amax and biomass were found in 51 and 85 mM NaCl treated plants, but not in 17 mM concentrations. Results imply that the three species have differentiated in their sensitivity to salinity, with G. soja being the most sensitive, G. tabacina intermediate, and G. tomentella the least sensitive. The three species also differed in leaf tissue concentrations of Na and K. A negative correlation between Na accumulation in leaf tissue and salt tolerance was found that contrasted to a positive correlation between K concentration in leaf tissue and salt tolerance.