Behavior of cowpe beans according to the application of phosphorus sources in association with the bacteria Bacillus subtilis in the spring/summer period

The culture of cowpea has great socioeconomic importance, generating employment and income for the population. One of the main obstacles to the productive increase of this culture in the Cerrado region is the low availability of phosphorus. The symbiotic association of the Bacillus bacterium with the plant through its ability to solubilize phosphate is an interesting tactic to be explored. Thus, the objective was to evaluate the behavior of the cowpea cultivar BRS Guariba as a function of phosphorus sources and different times of application of the bacterium Bacillus subtilis. The experiment was carried out in a factorial scheme (2x4), with two sources of phosphorus (Formulated NPK 5-25-15 and Natural Phosphate) and four times of application of the bacterium B. subtilis (Witness, sowing, V4 and R6) in the spring/summer period. The experimental design adopted was in randomized blocks with four replications. Agronomic and physiological characteristics were evaluated. Significance was observed between the interaction of factors for the characteristics number of pods per plant (NPP) and productivity (YLD). The use of Formulated NPK (5-25-15) together with the application of the bacterium B. subtilis at stage V4 reached the highest average for this characteristic NPP (4,10) and YLD of 1538.44 Kg ha-1. There was no significant effect for stomatal chlorine A and B. The phosphorus source factor influenced the physiological components of Transpiration Rates Conductance rate and Internal CO2 concentration in the leaf.