Effect of inoculation with fast - and slow-growing rhizobia on soybean (cv.Tropical) in an acid soil as affected by liming

O experimento foi conduzido com solo ácido da Zona da Mata do Estado de Pernambuco, submetido a diferentes níveis de calcário (0, 2, 4 e 8 t há-1), para avaliar a fixação do N2 e o desenvolvimento da soja, Glycine Max (L.) Merril, (cv. Tropical) (Leguminosae-Faboideae) com estirpes previamente selecionadas para resistência à acidez (NFB 175, de crescimento rápido, e SEMIA 542, de crescimento lento), com inoculante comercial e sem inoculação. Houve efeito na nodulação, na atividade da nitrogenase, na produção de biomassa seca e no N total da parte aérea. As estirpes NFB 175 e SEMIA 542 foram tão efetivas quanto o inoculante comercial. A adição de calcário beneficiou a fixação do N2 e o desenvolvimento da soja. Entretanto, os níveis mais elevados de calcário tiveram efeito prejudicial sobre as plantas inoculadas com as estirpes NFB 175 e SEMIA 542, indicando a necessidade de controle da calagem para a soja em solo ácidoThe experiment was conducted in order to evaluate the effect of selected fast and slow-growing rhizobia strains (NFB 175, SEMIA 542) on nitrogen fixation and development of soybean, Glycine max (L.) Merril, (cv. Tropical) (Leguminosae-Faboideae) growing in acid soil of the “Zona da Mata” of the Brazilian Northeast submitted to different levels of lime (0, 2, 4 e 8 t ha -1). Commercial inoculant and treatment without inoculation were applied for comparative purpose. It was observed effect of rhizobia inoculation on nodules dry biomass, nitrogenase activity, shoot dry biomass and total N total yield. The fast and slow growing rhizobia strains NFB 175 and SEMIA 542 are as effective as commercial inoculant. The addition of lime had benefit on nitrogen fixation and soybean growth. However, it was observed negative effects of lime in higher levels when used on fast and slow-growing strains, indicating the need of liming control on soybean growing in acid soil