Iron Signaling in Oxidative Stress of Plants Under Saline Conditions, A Meta-Analysis

Iron is a nutrient that plays various roles in biological processes of plant cells and can increase the resistance of plants to salt stress. This research was conducted to quantify the effects of iron on the growth and reduction of oxidative stress of plants under salinity. The results indicated that the foliar application of iron improves growth and reduces oxidative stress in plants under salt stress. Application of iron in moderate (5–7 dSm−1) and high salinities (greater than 7 dSm−1) had better effects on plant growth, compared to low salinities (less than 5 dSm−1). The best doses of iron foliar treatment for increasing growth and activation of antioxidant enzymes are low (less than 500 mg l−1) and moderate (500–1000 mg l−1) doses, but high doses of iron (greater than 1000 mg l−1) is not desirable. The water-soluble forms of iron (saline forms) has better effects on the growth and antioxidant activities of plants in saline conditions, compared to the water-insoluble forms (oxide forms). The size of the iron particles (regular and nano size) for foliar application is not very affecting the results, therefore, plants treated with both nano and normal sizes of iron particles has a good ability to deal with salt stress. This study reveals that foliar application of iron in saline conditions improves plant biomass (up to 24%), the activity of catalase (up to 19%), peroxidase (up to 11%) and superoxide dismutase (up to 14%) and reduces lipid peroxidation by about 15%.