Drought and UV-B radiation effect on photosynthesis and antioxidant parameters in soybean and maize

Drought and ultraviolet-B (UV-B) radiation are the most adverse factors for plant growth and productivity. The aim of this study was to compare the effects and interaction of drought and UV-B radiation in the seedlings of maize and soybean. The relative leaf water content was the main factor resulting in reduced growth in response to drought. The anthocyanin and phenol levels were increased under UV-B radiation. Drought and UV-B radiation caused great membrane damage, as assessed by lipid peroxidation and osmolyte leakage. Catalase, peroxidase, superoxide dismutase and hydrogen peroxide were observed under both stress conditions. Proline increased primarily in drought-stressed seedlings and may be the drought-induced factor with a protective role in response to UV-B. The total dry matter of both plant species was decreased due to the chlorophyll content and photosynthetic rate decreased under single and combined stress conditions. UV-B radiation had more adverse effects on growth of maize and soybean seedlings than drought by the physiological and biochemical parameters measured.