GROWTH, (CO2)-C-14 FIXATION, ACTIVITIES OF PHOTOSYSTEMS, RIBULOSE 1,5-BISPHOSPHATE CARBOXYLASE AND NITRATE REDUCTASE IN TREES AS AFFECTED BY SIMULATED ACID-RAIN

In seedlings of the tropical tree species Erythrina variegata I,am. an d Hardwickia binata Roxb. exposed to different acidic mist (H2SO4 PH 5 , 3 and 2) for 5 d significant reduction in seedling growth, biomass a ccumulation and (CO2)-C-14 fixation were determined. In isolated chlor oplasts a decrease in the activities of photosystem 2 and whole electr on transport chain was observed only at PH 3 and 2, but no significant change in photosystem 1 activity was observed. SDS-PAGE analysis of c rude leaf extracts of ribulose 1,5-bisphosphate carboxylase (RuBPC) in dicated a significant loss of 55 and 15 kDa polypeptides at pH 2 in Er ythrina. The reduction in the RuBPC activity in seedlings grown under acidic mists correlated well with CO2 fixation.