Exclusion of solar UV-B (280-315 nm) radiation on vegetative growth and photosynthetic activities in Vigna unguiculata L.

The impact of solar radiation with and without UV-B component was studied i n a tropical legume Vigna unguiculata L. The average level of ambient UV-B was 10 kJ m(-2) day(-1). Exclusion of solar UV-B increased the seedling hei ght, leaf area and fresh weight. On a unit fresh weight basis, a 50% increa se in total chlorophyll and 47% decrease in flavonoids was noticed after 20 days of growth. Decrease in flavonoid content in W-B filtered seedlings in dicates the plant responsiveness to minimal W-B radiation existing inside t he filter cage. W-B exclusion during the early phase of seedling growth als o promoted photosynthetic activities, measured as O-2, evolution or fluores cence transients. Such an enhancement in activity was attributed to modific ation in thylakoid organization under UV-B exclusion. (C) 1999 Elsevier Sci ence Ireland Ltd. All rights reserved.