Evaluation of Enzymatic and Non-enzymatic Defense Mechanism in Response to Drought Stress During Growth Stage in Soybean

Soybean is a diploid plant with relatively wide range of environmental conditions and climate adaptation. Water deficit is first limitation that cause soybean yield reduction in dried and semi-dried regions. In addition to the physiological changes that occurs due to water deficiency in plants, oxidative damage is also an important factor limiting plant growth and production. In this study, the level of super-oxide and hydrogen peroxide were measured, also the amount (of) super-oxide dismutase and catalase enzyme as well as ascorbic acid, α-tochopheroll, cartenoid and TBARM (cellular oxidative level) were assessed. Three soybean genotyps (DPX, sari and WE6 Line) were evaluated for above traits in three drought stress treatments included 50mm evaporation (as control), 100mm and 150mm evaporation from A class evaporation pot. Leaf samples collected for each treatments in three reproductive stages (flowering, pod elongation and seed filling). The variance analysis results showed that drought stress treatment had significant effect on all measured traits. Base on this, enzyme activity (super oxide and catalase) and non-enzymatic antioxidants (ascorbic acid, carotenoid and α-tocopherol) had a key role in response to drought stress in studied soybean genotypes. DPX cultivar and WE6 line showed superior antioxidant agents activity in comparison with sari cultivar in drought stress conditions.