THE INFLUENCE OF ARSENITE CONCENTRATION ON ARSENIC ACCUMULATION IN TOMATO AND BEAN-PLANTS

Arsenic (As) absorption by tomato (Lycopersicum esculentum Mill) and b ean (Phaseolus vulgaris L.) as affected by arsenite concentration in n utrient solution was examined. The processes of As uptake and accumula tion among roots, stems, leaves, and fruit were studied. Tomato and be an plants were grown in nutrient solution containing four levels of ar senite: 0, 2, 5, and 10 mg As l(-1) were dead after 36 days of treatme nt. In tomato, As exposure resulted in a significant reduction in dry biomass production but tissue chlorosis or necrosis were not observed. The strategy developed by tomato plants to tolerate As was avoidance; limiting As transport to shoots and increasing As accumulation in the root system. Arsenic in tomato root tissue seemed to be so effectivel y compartmentalized that its impact in plant growth and metabolism was minimal. However, in bean plants upon uptake, As was readily transpor ted to shoots and accumulated to high concentrations in leaf tissue. T he observed differential absorption and translocation of arsenite or i ts metabolized species by tomato and bean plants were probably respons ible for the different plant tolerance to As pollution. (C) 1997 Elsev ier Science B.V.