Investigating Iron Oxide Nanoparticles and Piriformospora indica Roles in Mitigating the Harmful Effects of Drought Stress in Soybean: Antioxidant Enzymes and Oil Content

Drought stress is one of the most important environmental stresses that affects the quantity and quality of soybean production. This study was conducted to explore the role of iron oxide nanoparticles (NPs) application and Piriformospora indica inoculation in alleviating the adversities of drought stress on fatty acid composition and oil production in soybean. The results showed that seed oil synthesis was considerably reduced by drought stress, whereas the membrane lipid peroxidation was accelerated under drought stress condition. The applied NPs (especially 0.75g L-1 ) and P. indica enhanced the activities of enzymatic antioxidants (SOD, CAT, PPO and APX) with simultaneous decrease in malondialdehyde. Under drought stress, an inverse relationship between protein and seed oil was observed, as by increasing protein content, seed oil decreased linearly. In addition, the main oil constituents, oleic and stearic acids increased, while linoleic, linolenic and palmitic acids reached to the lowest level in severe drought stress (FC 20%). Interestingly, the beneficial effects of NPs and P. indica led to improvement in grain weight, fatty acid composition and oil content under drought stress. During drought stress, oleic, linoleic, linolenic and palmitic acids increased and stearic acid decreased considerably in P. indica and NPs treatments. However, combined NPs and P. indica was generally more effective in alleviation of drought stress deleterious effects than individual treatments.