Shoot dry weight, chlorophyll and UV-B-absorbing compounds as indicators of a plant's sensitivity to UV-B radiation

When studying the effects of ultraviolet-B (UV-B) radiation on plants, a good measure of UV-B sensitivity is a decrease in dry weight, since this reflects the cumulative effect of many small disruptions in plant Function. Measurements of chlorophyll concentration and the level of UV absorbing compounds are also used to gauge plant health during and after UV-B exposure. When a variety of vegetable crop plants were screened for UV-tolerance, it was found that the levels of chlorophyll and UV-absorbing compounds did not correlate with sensitivity. Biomass accumulation was, however, correlated with UV-sensitivity; plants that accumulated more biomass over a 2-week period were more likely to be UV-B sensitive. This suggests that a rapid growth rate renders plants more sensitive to the injurious effects of UV-B radiation. (C) 2000 Annals of Botany Company.