Abstract: 【Objective】 The effects of enhanced UV-B radiation and drought stress on growth, production, and biomass of three spring wheat varieties were studied to provide a basis for breeding spring wheat varieties of high yield and tolerance to drought and anti UV-B radiation. 【Method】 Drought, enhanced UV-B radiation, and interaction between drought and enhanced UV-B radiation were set to analyze the morphologic index such as flag leaf area, leaf thickness, leaf area index, biomass, root to shoot ratio, and production harvest index, and other biological indicators of three spring wheat cultivars in northwestern China as well. 【Result】 The results showed that enhanced UV-B radiation restrained the node-tillering, resulting in decreased number of tillering nodes, and that moderate drought increased the number of tillering nodes. Under the enhanced UV-B radiation and drought, the biomass of Dingxi-24, Longchun-8139 and Heshangtou reduced by 22%, 21% and 15%, respectively, the average reduction of biomass was 20%. Drought had a less adverse effect on harvest index and yield than enhanced Ultraviolet-B radiation and the interaction between them did. Drought stress increased the harvest index of Heshangtou and Dingxi-24 by 10%, Longchun-8139 by 23%. In contrast, enhanced ultraviolet radiation-B decreased the harvest index of Heshangtou by 10%, and it increased the harvest index of Dingxi-24 and Longchun-8139 by 10%. This indicated that different species allocated inequable proportion of biomass to procreation growth under enhanced ultraviolet-B radiation, drought and the interaction between them. 【Conclusion】 There is a difference among varieties of spring wheat under enhanced ultraviolet-B radiation and drought. Response trend of the three species to enhanced ultraviolet-B radiation and drought is by and large accordant. Drought and enhanced ultraviolet-B radiation had a restraining effect on the three species, but sensible difference amongst species. Longchun-8139 showed a lower number of tillering nodes, highest harvest index and yield in contrast to Heshangtou and Dingxi-24 under enhanced ultraviolet-B radiation and drought. Therefore, Longchun-8139 had more advantages over Heshangtou and Dingxi-24 under enhanced ultraviolet-B radiation and drought.

Key words: enhanced Ultraviolet-B, drought stress, spring wheat, growth, biomass