Inoculação de sementes como estratégia para maximizar a fixação biológica de nitrogênio no feijão-caupi

Abstract

Cowpea is a strategic crop for semi-arid regions due to its adaptability and economic importance, and it is also favored by sustainable practices such as biological nitrogen fixation, which represents an alternative to nitrogen fertilization in legumes grown in low-fertility soils. This study evaluated the efficiency of seed inoculation with Bradyrhizobium pachyrhizii BR 3262, at different doses, with and without nitrogen fertilization, as a strategy to enhance biological nitrogen fixation. The experiment was conducted in pots, using a completely randomized design in a 4 × 2 factorial scheme, with four replications. The variables analyzed included morphophysiological characteristics and nodulation. Mineral nitrogen fertilization completely inhibited nodule formation. Inoculation without N favored nodulation. There were no statistical differences in the morphophysiological variables, although higher doses of inoculant showed a trend toward reduced shoot dry mass. Chlorophyll index values remained above 45, even without N application. Inoculation with Bradyrhizobium pachyrhizii BR 3262 proved efficient in inducing biological nitrogen fixation under low-fertility conditions, representing a sustainable alternative to nitrogen fertilizers.