-Brazil is a major producer and exporter of beef in the world, 90% of the production is made in pasture and 85% of cultivated pastures in the country are Brachiaria sp. With a growing livestock industry in the recent years, several forage plant diseases became significant importance for causing losses in pasture productivity and quality. This study aims at quantifying the species of fungi associated with seeds and their frequency in forage plants from tropical regions of Brazil. Assays were performed considering: incidence, pathogenicity and seed-seedling transmission of fungi associated with seeds. Therefore, 28 lots of forage species seeds produced in the harvest of 2010-2011 were used. Fourteen genera of fungi associated with seeds were found, among which Bipolaris sp., Phoma sp., and Curvularia sp. had pathogenic potential. It was possible to note that Bipolaris sp., is prejudicial to forage seedlings of Brachiaria, Panicum and Crotalaria. Bipolaris sp. and Curvularia sp. have an average of seed-seedling transmission of 100% and 90%, respectively.
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.
One of the main causes of low productivity of cowpea crops in Brazil is the use of low quality seeds. Low quality seeds have a high degree of infestation by phytopathogens, mainly fungi. Seed treatment with biological control agents, such as fungi of the genus Trichoderma, is a useful alternative to reduce or inhibit the transmission of diseases via seeds. In view of the above, this study aims to evaluate the physiological and sanitary quality of cowpea seeds treated with conidia of Trichoderma sp. (1.2, 2.4, 4.8 and 9.6 x 108 CFU g-1). We evaluated the germination and the sanity of seeds, length of seedling radicles, and production of indole acetic acid (IAA) by fungi. The experimental design was completely randomized in all experiments. In general, there was a predominance of Fusarium spp. and Rhizoctonia solani. The treatment of seeds with the conidia of Trichoderma sp. was positive for the parameters related to germination and radicle length of cowpea beans up to the concentration 4.8 x 108 CFU g-1. We conclude that the application of Trichoderma sp. was efficient in reducing the incidence of Fusarium spp., and promoted the germination and elongation of the radicle in cowpea.
This study aimed to evaluate the efficiency of simultaneous inoculation of isolates from rhizobia and Trichoderma in cowpea and their effects on its growth, nodule quality and grain yield. In the experiment under greenhouse conditions, the cowpea cv. Vinagre, of a medium-late cycle, was used in a test with a completely randomized design. In the field test, three cowpea cultivars (Vinagre, Fradinho and Sempre Verde) were used in a randomized block design, with seven treatments and three replicates. The variables evaluated in the greenhouse were biomass, nodulation and relative efficiency (RE) while the yield was evaluated in the field. Seeds inoculation of cowpea with Trichoderma and rhizobia, in the greenhouse, followed by an additional Trichoderma shoot application at 25 days after sowing (DAS), was relevant for biomass accumulation, with no difference in the nitrogen application and nodulation. Applying rhizobia was important for the root development. Seed inoculation with rhizobia and Trichoderma followed by another Trichoderma application at 25 DAS, provided increased yield in the three studied varieties, under field conditions.
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