Phosphorus uptake as a criterion for selecting aluminum tolerant soybean genotypes

Abstract

This experiment was carried out to evaluate the effectiveness of phosphorus (P) uptake Kinetic parameters as indicators of aluminum (Al) tolerance of soybean (Glycine max (L.) Merrill) cultivars. Seedlings of six soybean cultivars (Bragg, IAC-2, UFV-1, UFV-4, UFV-79-55, and UFV-80-65) were grown in complete nutrient solution, in which 2 ppm Al were applied or not. Then they were transferred to a growth chamber and the P uptake study was conducted following the Claassen-Barber approach. Plants of IAC-2, UFV-4, UFV-79-55, and UFV-80-65 increased their P uptake when Al was present in the nutrient solution. Under this condition, there was a decrease in the uptake of P by plants of Bragg and no changes in those of UFV-1. The rate of P uptake by plants in the presence of Al followed the order: UFV-4 > IAC-2 > UFV-1 > UFV-79-55 > UFV-80-65> Bragg. The Imax values of IAC-2 and UFV-1 increased and those of UFV-80-65, Bragg, UFV-79-55, and UFV-4 tended to decrease when Al was present in the nutrient solution. On the other hand, the Km values of all cultivars increased in presence of Al. It is concluded that the parameters Imax and Km of P uptake are good indicators of Al tolerance of soybean cultivars, and can be used for screening programs.