Intraspecific responses in crop growth and yield of 20 wheat cultivars to enhanced ultraviolet-B radiation under field conditions

Field studies were conducted for a season to determine the effect of enhanced ultraviolet-B (UV-B, 280-315 nm) radiation on crop growth, grain yield and the intraspecific variation in sensitivity of 20 wheat (Triticum aestivum) cultivars. The supplemental UV-B radiation was 5.00 kJ m(-2), simulating a depletion of 20% stratospheric ozone. Out of 20 wheat cultivars tested, 10, 5 and 12 had significant change in plant height at 40 days after planting (DAP), 50 DAP and ripening stages, respectively. Sensitivity in plant height: ripening stage>40 DAP>50 DAP. Area per leaf (LA) of 5 cultivars and leaf area index (LAI) of 9 cultivars had significant difference between control and UV-B radiation. Sensitivity in LAI was more than that in LA. While 14 cultivars showed significant change in tiller number, 13 and 15 had significantly less shoot biomass and smaller grain yield, respectively. The result showed that 19 out of 20 wheat cultivars had a negative response index (RT), indicating inhibition by UV-B radiation on wheat growth, while only Dali 905, the most tolerant cultivar, showed positive response (RI 74.71). The response index of 7 tolerant cultivars was higher than -70; 5 out of 7 originated in South China (low latitude). Meanwhile, the response index of 9 tolerant cultivars was lower than -120, the most sensitive cultivars, i.e. Huining 18 (RI 231.91) and Longchun 16 (RI 224.23), originated in North China (high latitude). These UV-B tolerant cultivars identified and evaluated from our study might be useful donors for further breeding program. (C) 2000 Elsevier Science B.V. All rights reserved.