Abstract: A field experiment was conducted to investigate effects of enhanced ultraviolet-B(UV-B)radiation on physiological characteristics,e.g. photosynthesis and transpiration,of different cultivars of barley.The experiment was designed to have two levels of UV-B radiation,i.e. enhanced UV-B(14.4 kJ·m^-2·d^-1)and ambient UV-B,and conducted at the Agro-Meteorological Station,Nanjing University of Information Science and Technology,Jiangsu Province,China.Results show that enhanced UV-B obviously depressed photosynthesis and transpiration in all the barley cultivars.Compared with control,enhanced UV-B radiation significantly decreased chlorophyll content,stomatic conductance,net photosynthetic rate and transpiration rate,but generally had no effect on intercullular CO₂ concentration in the leaves of the plants.However,the plants varied in sensitivity to UV-B radiation from cultivar to cultivar.Cultival Dan #2 was more sensitive than Cultivar Su #4.