Effects of enhanced ultraviolet-B radiation on crop structure,growth and yield components of spring wheat under field conditions

Spring wheat (Triticum aestivum) was grown in the field for two consecutive seasons under ambient and supplemental levels of ultraviolet-B (UV-B, 280–315 nm) radiation to determine the potential for alterations in community structure, developmental stages, growth and yield components. The supplemental UV-B radiation simulated depletions of 12, 20, or 25% stratospheric ozone. Spring wheat is a potentially UV-B sensitive species, showing the greatest sensitivity to UV-B radiation at 5.31 kJ m⁻². Delays in development and decrease in plant height were observed at early tillering stage under UV-B treatment, and slowly exacerbated during further development. UV-B radiation changed crop structure, by decreasing the total number of tillers produced and increasing dead shoot number, resulted in fewer head-bearing shoots at ripening stage, and decreased biomass and yield. UV-B radiation decreased the area of the last leaf and leaf area index, but increased specific leaf weight. UV-B radiation inhibited biomass accumulation and altered the patterns of biomass partitioning; these effects might be correlated with yield. Decreases in yield were the result of significant reductions in spike number, grain number per spike and thousand grain weight under UV-B. Generally, the effects of UV-B radiation on developmental stages and crop structure were the most important, they might change the other characteristics of spring wheat crop. The responses of spring wheat crop to enhanced UV-B radiation were assessed, decreases in some crop characteristics caused by a 10 or 20% global ozone depletion were predicted. Ozone depletion had the greatest decrease in yield and the least reduction in plant height.