The expansion of the soybean crop has evidenced a high host specificity, indicating the requirement of new strains with capacity of nodulating soybean and competition capacity with the natural soil rhizobial population. The purpose of this study was to evaluate the host specificity of mutants isolated from Bradyrhizobium spp strains in relation to nodulation and relative N2 fixation effectiveness in soybean (cultivars Peking and Clark), cowpea and pigeon pea. The experiment was carried out under controlled conditions in a growth […]

Soybean [Glycine max (L.) Merrill] and common bean (Phaseolus vulgaris L.) crops are of economical and social importance in Brazil; their requirement for nitrogen can be supplied by the symbiosis with bacteria belonging to the order Rhizobiales. However, to guarantee the maximization of the biological nitrogen fixation, seeds must be inoculated with efficient and competitive strains of rhizobia recommended by research. In 2001/2002, 14 million doses of inoculant were sold in Brazil, 99 % of these for soybean and common bean crops. […]

In Brazil, Bradyrhizobium inoculation has successfully replaced the use of N fertilizer on soybean [Glycine max (L) Merr.] crops. However, with the expansion of no-tillage cropping systems in the Cerrados region, the idea that it is necessary to use small N rates at the sowing to overcome problems related with N immobilization has become widespread, mainly when soybean is cultivated after a non-legume crop. In this study we examined soybean response to small rates of N fertilizer under no-tillage (NT) […]