Abstract
The present study was conducted to evaluate the differences in photosynthetic parameters and antioxidant enzyme activity among two genotypes of soybean (Glycine max L.) in response to salinity stress. Ten-day-old seedlings, grown hydroponically, were treated with 0, 25, 50, 75, 100, 125 and 150 mM NaCl for 7 days and analysed for the traits as biomarkers for identification of salt-tolerant soybean genotype. It was observed that NaCl stress caused severe impairments in photosynthetic rate, chlorophyll fluorescence and chlorophyll content in both the genotypes, but the damage were much more pronounced in salt-sensitive genotype VL SOYA-47. Moreover, chlorophyll fluorescence measurements showed higher non-photochemical quenching in genotype VL SOYA-47 and lower in genotype VL SOYA-21. The antioxidant enzyme activities (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) was observed much higher in VL SOYA-21 than in VL SOYA-47 at various levels of NaCl treatments. From the results, it could be suggested that VL SOYA-21 is the salt tolerant and VL SOYA-47 is a salt sensitive soybean genotype. The tolerance capacity of VL SOYA-21 against NaCl stress can be related with the ability of this genotype in possessing vital photosynthetic system and ROS scavenging capacity.