ABSTRACT
Survival of Rhizobium meliloti strains in alfalfa seeds and in soil isolates from the Upper río negro valley and neuquén, argentina

Perla Gili S.1, Graciela Marando I. y Marcelo Sagardoy R.
 

Nitrogen fixation in alfalfa (Medicago sativa L.) cv. Cuf 101 inoculated with 40 strains of R. meliloti isolated from soils ofthe Upper Río Negro Valley and Neuquén, Argentina, was studied in growth chamber experiments. Eight strains were selected based on their re1ative infectiousness and capacity to produce biomass under controlled conditions. On evaluating the survival ofdifferent R. meliloti strains in inoculated seeds, with inoculants in sterile peat, it was found that the survival rate varied with the strain type in the bio-fertilizer. The results showed that it was possible to obtain, using irrigated soils and studying the saprophytic properties ofthe infective microsymbionts, infective and effective strains with high capacity for nitrogen fixation in alfalfa Cuf 101. Natural strains of R. meliloti were found with sufficient capacity to live for ten years in soils under environmental conditions.

Keywords: Symbiotic nitrogen fixation, inoculants, survival, Medicago sativa.
1 Universidad Nacional del Comahue (UNC), Facultad de Ciencias Agrarias, CP 8303, Cinco Saltos, Río Negro, Argentina.