Evaluation of salinity levels on yield and changes of antioxidant enzymes in soybean

To investigate the effects of salinity on chemical and biochemical activities of three soybean varieties, greenhouse experiment was performed as split plot in a randomized complete block design (CRD). In this experiment, the salinity levels included three levels of (S1=50), (S2=100) and (S3=150) MM and cultivars consisted of 3-digit of L17, Zan and 033. Based on the results, the antioxidant activity of both enzymes increased under salinity stress in all cultivars that indicate the activation of the antioxidant defense system in them. The cultivar L17 produced the highest grain yield (2869/17 and 636/29 kg ha) in normal conditions, while the cultivar 033 *Zan showed the highest amount of yield (634/97 and 249/19 kg ha) at level of severe stress (S3). This cultivar between the other cultivars had the lowest amount of grain yield from the favorable conditions of irrigation to severe stress level. This cultivar in the part of chemical and biochemical results compared to the other varieties from the favorable conditions of irrigation to severe stress of salinity had respectively the highest and the lowest increase in antioxidant. It can be concluded from the mentioned results which this cultivar is likely better than other varieties in terms of physiological and agronomic traits.