Abstract: In this paper,field studies were conducted to determine the potential of alterations in physiology,and the intraspecific differences in sensitivity of 10 wheat (Triticum aestivum) cultivars to enhanced UV-B radiation.The supplemental UV-B radiation was 5.00 kJ·m^-2,simulating a depletion of 20% stratospheric ozone in Kunming area.The results showed that six of 10 tested wheat cultivars showed significant changes in total chlorophyll content,among which,chlorophyll a was strongly reduced,but chlorophyll b was reduced to a lesser extent,leading to a decrease in chlorophyll a/b ratio.The effects of UV-B on MDA and flavonoid contents also showed intraspecific difference.The MDA content of 5 cultivars was significant increased,while that of 2 cultivars was decreased.Four cultivars had significantly increased flavonoid content,but the flavonoid content in 2 cultivars was significantly decreased.The changes of chlorophyll and flavonoid contents were significantly correlated with the content of MDA (r=-0.78，P<0.01 and r=-0.75,P<0.05 respectively).There was a correlation between flavonoid and antiUV-B radiation of wheat.

Key words: winter wheat, irrigation mode, grain yield, water use efficiency, nitrogen use efficiency