| Under natural conditions,the plants of spring wheat were exposed to different intensities of ultraviolet-B(UV-B) radiation and the diurnal variations of their photosynthetic rate and water use efficiency (WUE) were recorded in Ningxia.Compared to the control group,the photosynthetic rate,transpiration rate,stomatal conductivity and water use efficiency was reduced by 19.0%,9.8%,22.7% and 12.1%,respectively,in the plants subjected to R1 dose UV-B radiation(0.5 W/m2),and by 48.8%,19.5%,53.6% and 37.2%,respectively,in the plants subjected to R2 dose UV-B radiation(1.0 W/m2). These results indicated that,within the range of UV-B radiation intensity used in this study,the photosynthesis and WUE of spring wheat tended to reduce with the enhancement of UV-B radiation intensity. |