SELECTION OF PASTURE LEGUMES TOLERANT TO ALUMINUM AND MORE EFFICIENT IN PHOSPHORUS UPTAKE .1. NATIVES LEGUMES

The aluminium tolerance and the phosphorus uptake efficiency of five populations of three native legume species (Desmodium leiocarpum, Adesmia latifolia and Adesmia tristis) were studied in a glasshouse at two lime levels (3,5 and 10.5 t/ha) and at four phosphate treatments (0, 66, 132 and 198 mg P/pot). The Vacarina soil (Haplohumox) used for the screening in this experiment is highly acid, high in exchangeable Al and low in P. The efficiency of phosphate utilization was expressed as: P-concentration in dry matter, P uptake per pot, P-utilization quocient and E-value. Based on the last two parameters Adesmia latifolia and Adesmia tristis 1 were the most efficient species at the low lime and at the lowest applied P levels. Adesmia tristis did not respond to increasing lime quantities and is therefore considered Al tolerant while Adesmia tristis 3 did not show any production response to increasing phosphate quantities, and was considered tolerant to low P in the soil.