Effect of exogenous potassium on photosynthesis and antioxidant enzymes of rice under iron toxicity

A solution culture experiment was conducted to determine the effects of different potassium concentrations on the chlorophyll fluorescence and oxidation resistance of the Fe2+-tolerant rice (Oryza sativa L.) genotype Xieyou 9308 and the Fe2+-sensitive genotype IIyou 838 exposed to 250 mg/L of Fe2+. The minimal fluorescence, maximum fluorescence efficiency, maximum fluorescence, and non-photochemical quenching coefficient showed no significant changes. However, the photochemical quenching coefficient increased. Under 200 mg/L K+ concentration, the effects of Fe2+ stress decreased. Compared with the control group, chlorophyll content and peroxidase, superoxide dismutase, and catalase activities decreased, whereas MDA content increased under Fe2+ stress. Exogenous K+ alleviated Fe2+ toxicity in the test subjects compared with the control group. Overall, external K+ could alleviate the toxic effects of Fe2+ toxicity.