Resumen

LOPEZ, Marisol; MARTINEZ VIERA, Rafael; BROSSARD FABRE, Mariluz  y  TORO, Marcia. CAPACITY ATMOSPHERIC NITROGEN FIXATION OF NATIVE STRAINS OF VENEZUELAN ECOSYSTEMS. Agronomía Trop. [online]. 2010, vol.60, n.4, pp.355-362. ISSN 0002-192X.

The low eficiency of industrial nitrogen fertilizers, as well as the high energetic and environmental costs make necessarily generate low impact technologies like biofertilizers based on atmospheric nitrogen fixing bacteria to substitute partially or totally the industrial sources. The population of native microorganisms and its capacity of nitrogen fixation (CFN) were estimated using agitation-fermentation tests by bioproduct agitation during 72 h in the laboratory. Simultaneously strains were inoculated in the culture medium Ashby and Dimargon®-M and shaking daily by six hours for 15 d. A randomized design with three repetitions was used. Nine strains atmospheric nitrogen fixing free life bacteria (FNVL), were assessed, divided into two groups. Group 1 with four strains: FNGMBar; FNMGSRt4f; FNMGSRt2f; FNMGSRt1f, isolated from treatments evaluated in Þ eld with agroecological principles. And the group 2 with five strains: 9, 12, 17, T5 and B1 belong to the National Strain Collection of INIA-CENIAP. The nitrogen (N) produced by each strain and its equivalent in kg ha-1 was signiÞ cantly (P<0.05) different between treatments evaluated. All strains were pre-selected by its CFN and by maintain high populations, 1010 and 1013 CFU ml-1 in Ashby and Dimargon®-M mediums, respectively, ensuring high concentration and low doses of application. Group 1 could provide the soil between 46 and 50 and the group 2 between 39 and 48 kg N ha-1, respectively, in crops of socioproductive interest.

Palabras clave : native strains; nitrogen fixation; free-living bacteria; agroecosystems.

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