Tolerance of soybean cultivars to aluminium toxicity at the initial phase

Abstract

Soybean genotypes have different levels of tolerance to the phytotoxic effects of aluminum (Al3+) and analysis of this characteristic may potentialize the use of acid soils. Current research investigated the effects of aluminum in the germination and initial growth of 25 soybean cultivars and the identification of more tolerant cultivars susceptible to toxicity by Al3+. Assay was conducted at the seed laboratory of the Universidade Estadual de Mato Grosso do Sul in Cassilândia, Brazil. Toxicity by Al3+ was imposed by exposition of seeds to a diluted solution with 15 ?mol L–1 of Al3+, plus 1250 ?mol L–1 calcium. The pH of solution with Al3+ was adjusted to 4.3 by HCl 0.5 mol L–1. Randomized experimental design comprised four replications with 50 seeds from 25 soybean cultivars and two growth conditions of seedlings (control or stress by Al3+), with a total of 50 treatments. Treatments were evaluated by tolerance indexes to stress (ITE) for seed germination, length and dry matter of seedlings. Toxicity by Al3+ reduced germination and initial growth rate in all the 25 soybean cultivars. Cultivars TMG 7061 IPRO, TMG 7063 IPRO, TMG 7067, HO Paranaíba IPRO and NS 7505 IPRO were indicated since they were bred in acid soils and had the greater tolerance to aluminum toxicity. Cultivars RK 815 IPRO, RK 8317 IPRO and ST 777 IPRO were classified as susceptible to aluminum toxicity and should not be recommended for breeding in acid soils.