Responses of Azospirillum brasilense on Brachiaria brizantha under different soil amendments

The objective of this study was to evaluate the responses of Brachiaria brizantha to inoculation with Azospirillum brasilense in different soil amendments. Four soil amendment treatments were evaluated (Control, liming, combination of NPK fertilizers and liming + combination of NPK fertilizers), associated or not with the inoculant Azospirillum, in a completely randomized design, with five replicates per treatment. The experimental units consisted of plastic pots with a capacity of 12 liters, which were filled with 10 dm³ of sandy clayey loam soil. For soil correction, higher productions were found for the variables SPAD indexes, chlorophyll b content, carotenoids and chlorophyll a/b ratio. The soil correction factor provided greater production of green matter, dry matter, and leaf area index when using liming with NPK when compared to the control treatment. There was an increase in root volume and weight for the type of soil correction. The use of liming and combination of NPK fertilizers promoted greater development of plant height, tiller density, stem and leaf elongation, quantity and average final leaf size. The use of Azospirillum brasilense inoculation associated with soil correction is recommended, as it provides positive responses on the production of the aerial part and roots of Brachiaria brizantha.