Effects of solar UV-B irradiation on vegetative and generative growth of Bromus catharticus

Abstract

The effects of three different solar UV-B levels (no UV-B, 80 and 90% of ambient UV-B) on the growth, pigmentation, seed yield and seed quality of Bromus catharticus were studied. The results indicated that UV-B had a slight overall positive effect on the vegetative biomass production of Bromus. Morphology was more sensitive to UV-B showing reduced plant height and increased tillering by UV-B. Generative growth was much more sensitive to UV-B than vegetative growth: the number of seeds and the dry weight per seed almost doubled from the control to the 90% UV-B treatment. The germination of seeds from the different treatments was not significantly different under optimal conditions, nor was the C and N content. There was no evidence for increased flavonoid production or leaf weight ratio (LWR) in response to UV-B. Natural UV-B levels appeared not to damage Bromus, but only to result in changes in allocation that could be positive for the species reproduction in the wild.