UPTAKE, ACCUMULATION AND TRANSLOCATION OF ARSENATE IN ARSENATE-TOLERANT AND NONTOLERANT HOLCUS-LANATUS L

Uptake, translocation and accumulation of arsenate was determined in arsenate-tolerant and non-tolerant genotypes of Holcus lanatus L. Over a 6 h period of growth in 0.05 mol m-3 arsenate, non-tolerant genotypes accumulated arsenate to a much greater extent than tolerant plants. Tolerant plants transported a much greater proportion of As to their shoots compared with non-tolerant plants. Phosphate at a concentration of either 0.05 or 0.5 mol m-3 decreased arsenate uptake in both tolerant and non-tolerant genotypes. When arsenate uptake was determined over 3 d at the same arsenate concentration, non-tolerant plants grown in the presence of 0 and 0.05 mol m-3 phosphate died, while those growing in 0.5 mol m-3 phosphate survived and continued to take up arsenate. At all three phosphate levels tolerant plants survived. Over the 3 d period transport of arsenate to the shoots decreased. With increasing phosphate levels in solution transport of arsenate to the shoots increased in tolerant plants. The results from these experiments are discussed in terms of strategies for metal tolerance in this species.