The Effect of Zinc and Potassium Treatments on the Antioxidant Activities and Physiological Responses of Canola in a Saline Soil

Salinity stress is one of the factors that affect the agricultural productions in the arid regions in the world. In this condition, the effect of potassium and zinc fertilizer treatments on the production of reactive oxygen species were investigated in a completely randomized design with three factors (fertilizer, cultivar, and time) and three replications in a greenhouse. The results showed that the application of potassium treatment in Sarigol and Licord cultivars increased SOD activity 49.1% and 14.4% respectively, as compared to the other fertilizer treatments. On the other hand, the application of this fertilizer increased the activity of GPX enzyme in Sarigol and Licord cultivars 50.7% and 62.2% compared to the other fertilizer treatments, respectively. The highest activities of SOD and GPX were in pre-flowering stage which showed 18.6 and 32.6% increasing related to flowering stage and 44.9 and 26.1% increasing related to post-flowering stage, respectively. Also, the relative water content of Sarigol and Licord cultivars increased by at least 7.9 and 0.35%, respectively, using potassium fertilizers. Sarigol cultivar had less potassium uptake than Licord cultivar in the root and shoot by 1.79% and 18.9%, respectively. Sarigol is a salt tolerant cultivar and sensitive in pre-flowering stage in which the consumption of potassium fertilizer can reduce the effect of salinity stress.