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This paper aimed to evaluate the effects of herbicides on the biomass and nodulation ofcowpea. The experiment was conducted in greenhouse, in experimental design with randomized blocks, in factorial arrangement 4x2 + 2, corresponding applications of the herbicide bentazon, clethodim, fomesafen and smetolachlor, the recommended dose (RD) and recommended twice (RDA) in four periods of development of cowpea (20, 30, 45 and 55 days after planting, DAP). An inoculated control treatment without herbicide application and a control without inoculation, no application of herbicide and nitrogen fertilizer were included. Inoculation was performed with the strains INPA UFLA 03-11B and 03-84. The results showed for the experiment in a greenhouse that bentazon and clethodim, both at the recommended dose and double dose, provide low phytotoxicity to cowpea and has little influence on nodulation and crop biomass. The herbicide smetalochlor presents high degree of phytotoxicity in cowpea, completely inhibits the vegetative growth when applied at twice the recommended dose.

In flood plains, cover crops are able to alter soil properties and significantly affect rice nutrition and yield. The aims of this study were to determine soil properties, plant nutrition, and yield of tropical rice cultivated on flood plains after cover crop cultivation with conventional tillage (CT) and no-tillage system (NTS) at low and high nitrogen (N) fertilization levels. The experimental design was a randomized block in a split-split-plot scheme with four replications. In the main plots were cover crops sunhemp (Crotalaria juncea and C. spectabilis), velvet bean (Mucuna aterrima), jackbean (Canavalia ensiformis), pigeon pea (Cajanus cajan), Japanese radish (Raphanus sativus), cowpea (Vigna unguiculata) and a fallow field. In the subplots were the tillage systems (CT or NTS). The nitrogen fertilization levels in the sub-subplots were (10 kg N ha-1 and 45 kg N ha-1). All cover crops except Japanese radish significantly increased mineral soil nitrogen and nitrate concentrations. Sunhemp, velvet bean, and cowpea significantly increased soil ammonium content. The NTS provides higher mineral nitrogen and ammonium content than that by CT. Overall, cover crops provided higher levels of nutrients to rice plants in NTS than in CT. Cover crops provide greater yield than fallow treatments. Rice yield was higher in NTS than in CT, and greater at a higher rather than lower nitrogen fertilization level.

The study aimed to examine the response of cowpea Vinegar cultivarwith inoculation of rhizobia and Trichoderma spp. at cerrado environment in Gurupi – TO, in the years of 2011 and 2012. The experiment was conducted under field conditions and experimental design of randomized blocks, corresponding to the treatments: inoculation with rhizobia and Trichoderma spp. in the seed; the seed inoculation with rhizobia and Trichoderma spp. in the soil; the seed inoculation with rhizobia and Trichoderma spp. in the seed and soil; only inoculation with rhizobia; fertilized with nitrogen; and control non-inoculated and non-fertilized with nitrogen. Inoculation was performed with the rhizobia strains INPA 03-11B and UFLA 03-84. For treatments with Trichoderma spp. was used to inoculate commercial Trichoplus JCO powder formulation. The results indicated that the potential for nitrogen fixation of rhizobia strains tested, and the Trichoderma bioprotection was of fundamental importance for biomass, production, nodulation and yield, which may be related with the effective capacity to supply nitrogen and protection against pathogens. Generallythe inoculation with rhizobia and Trichoderma in the seed and soil, provided better results on the variables analyzed for both season, with higher productivity than other treatments