Symbiotic effectiveness and ecological characterization of indigenous Rhizobium loti populations in Uruguay.

AUTOR(ES)

BARAIBAR, A.

FONTE

Pesquisa Agropecuaria Brasileira

DATA DE PUBLICAÇÃO

2011

RESUMO

The objective of this work were to describe the distribution, density and seasonal variation of the indigenous populations of Rhizobium loti in different Uruguayan soils and to determine symbiotic effectiveness and stress tolerance factors of different isolates, both with the aim of obtaining selected strains to re-introduce as inoculants in Lotus pastures. R. loti was present in ten soils studied and their densities varid from year to year and within each soil. All the isolates nodulated Lotus corniculatus effectively. The nodules in Lotus penduculatus and Lotus subbiflorus were small, red on the surface and ineffective in nitrogen fixation. The study of 50 isolates from the ten soils showed high variability in their symbiotic efficiency and tolerance to pH. The indigenous population was acid tolerant in culture medium (pH 4.5), 83% of them could grow at pH 4.5 in 3 days. This work showed that there was a great diversity between the strains of R. loti isolated form Uruguayan soils and supports the importance of selecting among them the most efficient and resistant strains to be included in the inoculants.

ASSUNTO(S)

lotus corniculatus lotus pedunculatus rhizobial ph tolerance tolerancia do rizodio ao ph

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