EFFECTS OF UV-B IRRADIANCE ON BIOMASS AND UPTAKE OF NUTRIENTS IN MANGROVE SEEDLINGS OF RHIZOPHORA-APICULATA (RHIZOPHORALES, RHIZOPHORACEAE)

Effect of ultraviolet-B (UV-B) irradiation was studied on hydroponical ly grown Rhizophora apiculata seedlings in terms of biomass and nutrie nt accumulation. The seedlings were exposed to four levels of UV-B irr adiation equivalent to 10,20,30 and 40% stratospheric ozone depletion at the study area along the southeast coast of India. There was an inc rease of biomass in seedlings exposed to low dose of UV-B. The Na/K ra tio was lower in leaves, but higher in stem and root of seedlings expo sed to UV-B. The degree of nutrient accumulation was in the decreasing order - root > stem > leaves. Translocation of nutrients from root to shoot seemed to be inhibited by UV-B.