Estresse por alumínio e por acidez em cultivares de soja

Abstract

Tropical and subtropical soils are frequently acid. In this paper four soybean varieties were contrasted in relation to germination and vigour of soybean (Glycine max L. Merril.) seedlings when seeds were submitted to aluminium concentrations (0; 0.25; 0.5; 1.0 and 1.5 mmolc dm-3 Al3+) and pH values (7.0; 6.0; 5.5; 5.0 and 4.5). The concentrations of aluminum did not affect germination and root dry weight, however, hypocotyl and root length, shoot dry weight and seedling vigour classification were affected. In the range between 0.25 and 1 mmolc dm-3 there was an improvement of the development of the seedlings (hypocotyl and root length). Root length had its greatest development at 1.0 mmolc dm-3 Al3+. Cultivars ‘Xingu’, ‘Pintado’ and ‘Pioneira’ presented the best results for all treatments. The pH treatments affected the germination, hypocotyl and root length, shoot and root dry weights and seedling vigour classification. The germination was superior at pH 6.0 while at pH 7.0 produced longer hypocotyls and roots, shoot and root dry weights. Cultivars ‘Xingu’, ‘Pioneira’ and ‘Pintado’ had the highest germination even in the most acid treatments, indicating that germination is not severely affected by the acidity of the substratum. The ‘Conquista’ was the most sensitive high acidity cultivar.