Salt and alkalinity-tolerant rhizobia from the Salado River Basin as a source of genetic and symbiotic variability to improve the quality of inoculants for L. tenuis.

BERGOTTINI, V.M., CASTAGNO, L.N., PAZ, R.C., RUIZ, O.A. Y ESTRELLA, M.J.

Estoril (Portugal)

Congreso; I Congreso Luso Español de Fijación de Nitrógeno y XII Reunión Nacional de Fijación de Nitrógeno (España); 2008

Sociedad Española de Fijación de Nitrógeno

The Salado river Basin (SRB) is the most important area for cattle raising in Argentina. This activity relies on natural pastures, given that the edaphic and climatic conditions restrict the implantation and persistence of ‘traditional" legumes’ in saline-alkaline lowlands (30% of the total area). L. tenuis is an exotic legume well adapted to these conditions, but in spite of its successful naturalization, the survival of this species during the seedling stage is limited and is a critical step for further implantation. With the aim of improving seedling survival and forage quality, the genetic diversity of native rizobia was evaluated, for further selection of isolates with a better symbiotic efficiency than commercial inoculants in saline soils. A high genetic diversity was found among the rizobia of the SRP. The symbiotic performance of two native isolates was superior to that of strains used as commercial inoculants both under control and salt stress conditions. It can be concluded that populations of rhizobia in soils of the SRP are a source of genetic and symbiotic variability that can be used to obtain high quality inoculants for L. tenuis.