Iron Sulfate (FeSO4) Improved Physiological Attributes and Antioxidant Capacity by Reducing Oxidative Stress of Oryza sativa L. Cultivars in Alkaline Soil

Rice ranks second among cereals in dietary uses around the world. Rice is deficient in iron (Fe), and these are important micronutrients for infants, men, and women. Fortification of rice with iron would help to minimize nutrient deficiency disorders among humans. The current study aims to introduce nutrient-rich rice. The effects of iron on germination, growth, photosynthetic pigment, antioxidant activity, and reduction of oxidative stress were investigated in four Oryza sativa L. cultivars. O. sativa of four different cultivars (Basmati-515, PK-386, KSK-133, and Basmati-198) were grown under five treatments (100, 200, 300, 400, and 500 mM) of iron sulphate (FeSO4) in soil of pH 7.5, along with control, by using six replicates. The result revealed that Fe treatment significantly affected seed germination percentage, plant growth parameters, biomass, photosynthetic pigments (chl a, chl b, total chlorophyll, and carotenoids), antioxidant enzymatic and non-enzymatic activity, and reduced oxidative stress. The findings also showed that Fe application reduced the oxidative stress including malondialdehyde content and hydrogen peroxide, by increasing the antioxidant enzymatic activity, i.e., catalase, ascorbate peroxidase, superoxide dismutase, peroxidase, glutathione peroxidase, 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), and non-enzymatic antioxidant compounds (proline, amino acid, total soluble protein, phenolics, flavonoids, reducing-non-reducing sugar, and carbohydrates) in all cultivars of O. sativa. Furthermore, FeSO4 induced a significant increase in proline, free amino acid, and total carbohydrates in the leaves of all O. sativa cultivars, but Basmati-198 showed the significantly highest content by 169, 88, and 110%, respectively, at concentration of 500 mM. The present research work showed that soil application of FeSO4 improved the seed germination, plant growth, and antioxidants enzymatic and non-enzymatic activity, denatured the ROS (reactive oxygen species) in alkaline soil. In order to understand the underlying mechanisms, long-term field investigations should be carried out at the molecular level to examine patterns of iron uptake and plant growth.