Combined inoculation of rhizobia and Trichoderma spp. on cowpea in the savanna, Gurupi-TO, Brazil

Abstract

The goal of this study was to evaluate the combined inoculation of rhizobia and Trichoderma spp. in cowpea, their ability to promote growth and use as a biological control agent for foliar blight (Rhizoctonia solani). The study was conducted in a field experiment in a randomized block design with four replications. The treatments consisted of seed-applied rhizobia with and without Trichoderma spp., and to the soil at planting time and 15 days after planting (DAP). The rhizobia inoculation was performed with a mixture of strains INPA 03-11B and UFLA 03-84. For the treatments with Trichoderma spp., a commercial powder product, Trichoplus JCO was used. The application of Trichoderma spp. and rhizobia at 15 DAP, in both the seed and in the soil, showed the best results (p < 0.05). The application of Trichoderma spp. did not inhibit the nodulation process, and the best results were obtained when the fungus was inoculated with rhizobia. The inoculation treatments were positive for Trichoderma spp. The Trichoderma spp. treatments showed improvements in stand counts, survival and effectiveness against R. solani, reinforcing that the usage of Trichoderma spp. as a seed and soil treatment.