Eficiência simbiótica de rizóbios em feijão guandu em casa de vegetação

Abstract

Pigeonpea is an important legume both in the use of animal feed and for the recovery of degraded areas. This legume is symbiotic with rhizobia, which biologically fix nitrogen (BNF). Thus, the selection of efficient rhizobia allows the maximization of this BNF. Thus, the objective of this work was to evaluate the symbiotic efficiency of different rhizobia strains for pigeonpea in the green house. For this purpose, trap crops with different types of soil were used and pigeonpea were used as host plants. Then the nodules obtained from the trap cultures were used in the strain isolation in Yeast-Mannitol-Agar. The strains were incubated in a bacteriological incubator for morphological (shape, elevation, consistency, pH modification) and biochemical (GRAM, catalase, oxidase, phosphate solubilization, indolactic acid production) characterization. The symbiotic efficiency´s evaluation was performed in a completely randomized experiment with four repetitions. Two controls with and without mineral nitrogen were also used in this experiment. The results showed that most strains were oxidase negative, catalase positive, acidify the culture medium, solubilize phosphate and show rapid growth. All strains were circular in shape, flat on the surface, smooth on the entire edge and opaque in colour. Furthermore, E11919, E11819, E10119, E11519 strains promoted greater nodulation (number and mass of nodules), the production of dry mass from the aerial part in water beans. It is concluded that the strains E11919, E11819, E10119, E11519 are more efficient and symbiotic.