Abstract

CARDENAS, Diana M; GARRIDO, María F; BONILLA, Ruth R  and  BALDANI, Vera L. Isolation and identification of Azospirillum sp. in Guinea grass (Panicum maximum Jacq.) of the Valle del Cesar. Pastos y Forrajes [online]. 2010, vol.33, n.3, pp.1-1. ISSN 0864-0394.

The effect of environmental factors of the Valle del Cesar and the agronomic management of Guinea grass (Panicum maximum Jacq.), on the bacterial population of the Azospirillum genus in semisolid NFb and LGI culture media was evaluated, for which an experimental design was used in divided plots with a 2 (climatic seasons: rainy and dry) x 2 (agronomic managements: agroecological and extractive) x 3 (analyzed samples: rhizospheric soil, roots and leaves) factorial arrangement. The results did not reveal significant statistical differences, which indicates that this bacterium can maintain its population under stress conditions by different physiological mechanisms. From these samples 16 isolations were obtained belonging to the Azospirillum genus in which their acetylene-reduction activity was evaluated as indicator of biological nitrogen fixation and their capacity in the production of indolic compounds as plant growth promoters. The strains SRGM2, SRGM3 and SRGM4, obtained from rhizospheric soil samples of Guinea grass of the Experimental Station Motilonia of Corpoica, Agustín Codazzi municipality, Cesar department, were selected. These isolations were molecularly characterized by the gen 16S rRNA and according to the BLAST analysis in the GenBank database and showed 93% similarity with A. lipoferum (SRGM2 and SRGM3) and 94% with A. brasilense (SRGM4).

Keywords : Growth; nitrogen fixation; Azospirillum sp.

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