Investigation of biochemical reactions and antioxidant enzymes activity of Quinoa under drought stress and fertilizer treatments in saline soil

The present experiment has been conducted as a split plot factorial based on completely randomized block design with three replications in 2018-2019 crop season on a saline farm (with an electrical conductivity of 5.2 dS/m) in Dastgerd area, Isfahan Province. Four levels of irrigation (25%, 50%, 75%, and 100% of FC) compose the main factors and biofertilizer (the control, Nitroxin, Biophosphorus, and their combination) as well as chemical fertilizer in two level of no application and integrated application of nitrogen and phosphorus fertilizers are the sub-factor. Severe drought stress (25% FC irrigation treatment) increase the measured traits (antioxidant enzyme activity including catalase, peroxidase, and superoxide dismutase along with Proline and Malondialdehyde content) in quinoa by about 46%, 52%, 142%, 42%, and 39%, compared to non-stress conditions (100% FC irrigation treatment), respectively. Also, they significantly reduce grain and biological yield in this plant (by about 76% and 49%, respectively). However, at all drought stress levels , the combination of nitroxin and biophosphorus under conditions of simultaneous use of chemical fertilizers of nitrogen and phosphorus shows the maximum effect on moderation of drought stress effects, significantly reducing the activity of antioxidant enzymes and, consequently, increasing yield, compared to other treatments at the same drought level. Overall, the results demonstrate that despite the salinity of the tested soil, quinoa has been able to complete its growth and seed production even under severe drought stress conditions.