Growth, photosynthesis and UV-B absorbing compounds of Portuguese Barbela wheat exposed to ultraviolet-B radiation

Wheat plants (Triticum aestivum L.) were exposed to two levels of UV-B radi ation (ambient UV-B and high UV-B, simulating a 20% reduction in the ozone layer) under mediterranean field-growth conditions. After 4 months of UV-B treatment, total plant biomass of high UV-B plants was 18% lower compared t o control plants. The decrease of biomass appears to be the result of chang es in morphological and physiological processes. High UV-B treatment induce s decreases in leaf area, net photosynthesis rate, transpiration rate and w ater use efficiency. Pigment analysis of leaf extracts showed increases in chlorophyll content and no effect on accumulation of UV-B absorbing pigment s. The underlying mechanisms for these results are discussed. (C) 1999 Else vier Science Ltd. All rights reserved.