Influence of ultraviolet-B radiation on photosynthetic and biochemical characteristics of a mangrove Rhizophora apiculata

Changes in photosynthesis and biochemical constituents were studied in R. apiculata seedlings grown under solar and solar enhanced UV-B radiation, equivalent to 10, 20, 30, and 40 % stratospheric ozone depletion. The seedlings grown under 10 % UV-B radiation showed an increase of 45 % net photosynthetic rate (PN) and 47 % stomatal conductance, while seedlings grown under 40 % UV-B radiation exhibited a decrease of 59 % PN with simultaneous elevation of 73 % intercellular CO2 concentration. Effects of UV-B on contents of lipids, saccharides, amino acids, and proteins were significant only at high doses of UV-B radiation. The concentration of anthocyanin was reduced with increasing doses of UV-B. The reverse was true with phenols and flavonoids.