Efficiency of combined inoculation of rhizobia and Trichoderma spp. in different cultivars of cowpea (Vigna unguiculata) in the 'cerrado' (Brazilian savanna)

Abstract

The study aimed to evaluate the efficiency of combined inoculation of Rhizobia and Trichoderma in cowpea (Vigna unguiculata). Three cultivars of cowpea, Corujinha, Fradinho and Sempre Verde were assayed. The experiment was conducted in a field in a randomized block design with four replications. The treatments used were simple and combined inoculations of Rhizobia and Trichoderma in the seed and in the soil, at planting and 15 days after planting (DAP). It was also included a control over fertilized with nitrogen and a non-inoculated control. Strains of Bradyrhizobium sp. were used for inoculation. Trichoplus JCO inoculant powder was used for treatments with Trichoderma. The parameters evaluated were biomass, nodulation, productivity, efficiency and symbiotic nitrogen content and phosphorus. The application of Trichoderma at 15 DAP in both the seed and in the soil showed the best results in most of the cultivars analyzed, overcoming the other treatments. Cultivar Corujinha showed the best results for biomass production. The application of Trichoderma did not inhibit the nodulation process, and the best results were obtained when the fungus was inoculated with Rhizobia.