The effects of enhanced ultraviolet-B radiation and soil drought on water use efficiency of spring wheat

The effect of enhanced ultraviolet-B radiation (280-315 nm) and water stress on water consumption, instantaneous water use efficiency (WUEi), season-long water use efficiency (WUEs) and leaf stable carbon isotope composition (delta C-13) of three spring wheat Cultivars (Triticum aestivum L) was investigated under held conditions. The relationship between WUEi and WUEs with delta C-13 was analyzed. Compared with the control, enhanced UV-B or water stress alone or in combination led to lower water use, and soil drought had a stronger influence oil water use than Supplementary UV-B irradiance. Soil drought increased the instantaneous water use efficiency (WUEi) and UV-B radiation decreased it significantly in comparison to the control. The combination of UV-B and water stress resulted in increased/reduced or no changed WUEi, different with change. Season-long water use efficiency (WUEs) showed the same trend as observed with WUEi under the conditions of UV-B radiation and water stress, except that no significant difference between control and drought in cv. Heshangtou. WUEs under the combined conditions of UV-B and water stress, was clearly increased in every cultivar. Enhanced UV-B radiation and the combination with drought led to negative foliar stable carbon isotope composition (delta C-13) and drought alone resulted in a positive Value for delta C-13. Tile relationship between foliar stable carbon isotope composition and instantaneous water use efficiency was not significant. Nevertheless, a positive correlation with, (delta C-13) against season-long water use efficiency was observed. The results indicated that delta C-13 can be a useable parameter for selecting a crop genotype having higher water use efficiency. (C) 2008 Elsevier B.V. All rights reserved.