Coinoculação de rizóbio e actinobactérias em feijão-caupi

Abstract

Rhizobia are Gram-negative bacteria that, in association with the root system of plants, induce the formation of nodules and convert atmospheric nitrogen into ammonia, an important compound for plant development. Equally important, actinobacteria are Gram-positive bacteria capable of producing several biologically active secondary metabolites, such as siderophores and phytohormones. In this context, the co-inoculation of these microorganisms in crops has demonstrated greater efficiency compared to single inoculations and nitrogen fertilizers, particularly regarding agricultural productivity. The objective of this study was to evaluate the effects of the coinoculation of a Bradyrhizobium strain (L47) and 21 Streptomyces strains on the growth of cowpea (Vigna unguiculata (L.) Walp), a legume widely cultivated in the Brazilian semiarid region and of great socioeconomic and nutritional importance. A randomized block design was adopted, with four replicates for the 24 treatments, which included the absolute control, mineral-N, single inoculation of L47 and 21 co-inoculations of L47 and actinobacteria strains (SN1, SN2, SN6, SN9, SN11, SN12, SN13, SN16, SN19, SN20, SN23, SN25, SN26, SN29, SN30, SN31, SN32, SN34, SN35, SN36 and SN38). The mean shoot dry mass (SDM), root dry mass (RDM), and nodule dry mass (NDM) were evaluated for each treatment, expressed as g plant⁻¹. Among the analyzed variables, RDM and NDM showed significant differences (p < 0.05). Theco-inoculations L47SN16, L47SN23, L47SN31, and L47SN36 achieved the best performance across all parameters. Therefore, the co-inoculation of rhizobia and actinobacteria emerges as a promising alternative for cowpea cultivation.