Assessment of consortia inoculation effects on the agronomical performance of the common bean

Abstract

The massive use of inputs is often applied in common bean for nitrogen (N) supply, better plant development, and to prevent plant disease. Instead, the co-inoculation of Rhizobium, Azospirillum and Trichoderma may play the same role; however, its effects are unknown in common bean. This work aimed to evaluate the effects of co-inoculating three microorganisms on the development, nodulation and grain yield (GY) of a common bean. The experiments were carried out on a randomized block design with four replicates. The treatments were NI: not inoculated; Rt: inoculated with Rhizobium tropici; Rt+Ab: inoculated with Rt and Azospirillum brasilense; Rt+Ab+Ta: inoculated with Rt, Ab and Trichoderma asperellum; Nf120: 120 kg ha−1 of N. In the inoculated treatments, the seeds were treated with Rt inoculant and with Ta inoculant before sowing, using a dose of 10 g of each inoculant kg−1 of seed. The inoculant containing the Ab was sprayed out in a dose of 300 mL ha−1 at the V2/V3 phenological stage. Evaluations were performed for the number of nodules (NN), nodule dry weight (NDW), root dry weight (RDW), shoot dry weight (SDW), pod number (PN), grain number (GN) and GY. NN and NDW were higher in NI and Rt treatments. The Rt+Ab treatment resulted in higher SDW, whereas the same treatment and Rt+Ab+Ta provided higher RDW and SDW, resulting in values similar to those of the Nf120 treatment. Innoculation with rhizobia (Rt) provided PN and GN equivalent to those of the Nf120 treatment. The inoculation (Rt) and co-iconulation (Rt+Ab) resulted on GY of 2946.27 and 2892.42 kg ha−1, respectively, surpassing the Nf120 treatment, which was 2741.91 kg ha−1. These results indicate that Rt inoculation and Rt+Ab co-inoculation can be alternatives to the substitution of nitrogen fertilizers, guaranteeing high GY levels in common bean.