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

Abstract

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 (δ 13C) of three spring wheat cultivars ( Triticum aestivum L.) was investigated under field conditions. The relationship between WUEi and WUEs with δ 13C 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 on 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 (δ 13C) and drought alone resulted in a positive value for δ 13C. The relationship between foliar stable carbon isotope composition and instantaneous water use efficiency was not significant. Nevertheless, a positive correlation with δ 13C against season-long water use efficiency was observed. The results indicated that δ 13C can be a useable parameter for selecting a crop genotype having higher water use efficiency.