Eficiência de bactérias promotoras de crescimento no desempenho de feijão-caupi crioulo em Pedro II-PI

Abstract

Cowpea (Vigna unguiculata (L.) Walp) is a strategic crop for food security and agricultural sustainability in the Brazilian semiarid region, although its productivity is limited by low nutrient availability, especially nitrogen. In this context, plant growth-promoting bacteria (PGPBs) emerge as a sustainable alternative, capable of stimulating plant development through multiple physiological mechanisms. This study evaluated the efficiency of bacterial strains in promoting the growth of three cowpea landraces grown in the municipality of Pedro II, Piauí, under greenhouse conditions. Two trials were conducted: the first in an autoclaved substrate and the second in natural soil with active microbiota. Shoot length (SPL), root length, nodule number, shoot dry mass (SDM), and root dry mass (RDM) were evaluated. In Trial I, isolates such as Enterobacter sp. (B1, B3, B7), Pseudomonas sp. (B2) and Bacillus subtilis (B9) promoted significant increases in all parameters, outperforming the controls, including nitrogen fertilization. In Trial II, only B1 (Enterobacter sp.) and B9 (Bacillus subtilis) maintained superior and consistent performance, even surpassing complete nitrogen fertilization, demonstrating greater ecological robustness and rhizosphere competitiveness. These results demonstrate that the effectiveness of BPCPs depends on their interaction with native microorganisms, and it is essential to validate strains in non-sterilized soils to avoid overestimations. We conclude that B1 and B9 have high potential as bioinoculants for cowpea, with the ability to reduce dependence on synthetic fertilizers, increase production resilience, and contribute to more sustainable agricultural systems. Keywords: Vigna unguiculata; BPCPs; bioinoculants; biological nitrogen fixation; agricultural sustainability.