Intraspecific differences in physiological response of 20 soybean cultivars to enhanced ultraviolet-B radiation under field conditions

Abstract

Field studies were conducted to determine the potential for alterations in physiology and the intraspecific variation in physiological sensitivity of 20 soybean cultivars to enhanced ultraviolet-B (UV-B, 280–315 nm) radiation. The supplemental UV-B radiation was 5 kJ m −2, simulating a depletion of 20% stratospheric ozone. Out of 20 soybean cultivars (from South China, North China) tested, twelve showed significant decreases in total chlorophyll contents. In most of these sensitive cultivars, chlorophyll a content was strongly reduced and chlorophyll b content decreased to a lesser extent, leading to a decrease in chlorophyll a/b ratio. However, Heidadou had an increased chlorophyll a/b ratio under enhanced UV-B. The effect of UV-B on flavonoid contents also showed cultivar differences: a significant increase in seven cultivars, decreases in five cultivars and no effect on the other eight cultivars. Membrane permeability of ten cultivars significantly increased, while that of six cultivars was significantly decreased. SOD activity of ten cultivars was significantly increased and that of six cultivars significantly decreased. MDA contents of three cultivars were increased significantly, while that of six cultivars was significantly decreased. Physiological indicators play a role in the sensitivity of soybean cultivars to enhanced UV-B radiation under field conditions. In 20 soybean cultivars, the responses of each physiological indicator to UV-B radiation were different. Intraspecific differences in the physiological responses of 20 soybean cultivars to enhanced UV-B radiation existed.