Caracterización y evaluación de rizobios como promotores del crecimiento en arroz

One of the interactions between plants and microorganisms of greatest biological and agronomic interest is the symbiosis between the Legume family and bacteria called rhizobia. These bacteria can also establish an interaction as endophytes with other families such as grasses and to enhance production in species such as rice (Oryza sativa). This crop is of particular importance in our country for its contribution to the national economy as well as for being a sector with international recognition in some aspects such as the quality of the exported product, the integration in the stages of the productive chain and the lines of research developed.

In this work, 14 rhizobial strains nodulating white clover (Trifolium repens) and 16 nodulating bird´s-foot trefoil (Lotus corniculatus), previously isolated from disinfected roots of rice plants from the long-term experiment of Paso de la Laguna, INIA, Treinta y Tres were characterized. The strains used in commercial inoculants U531 Mesorhizobium loti, U510 Mesorhizobium huakuii and U204 Rhizobium leguminosarum bv. trifolii were also included. The strains were screened for their colonization capacity and plant growth promoting traits, such as: symbiotic efficiency, pectin degradation, mobility, biofilm production, phosphate solubilization, indole acetic acid synthesis and ability to promote seed germination of Oryza sativa. The results showed variability among the strains, some strains stood out showing to be candidates to continue evaluating in inoculation tests.

Three of the strains nodulating Lotus corniculatus, 3 nodulating Trifolium repens and the strains of the commercial inoculants U510, U531 and U204 confirmed their interaction with rice plants cultivar INIA Olimar being able to colonize and persist in the roots up to 30 days post inoculation in greenhouse. Among the 9 tested strains, strain U204 Rhizobium leguminosarum bv. trifolii, showed the ability to promote growth of rice plants grown in sand: vermiculite showing a significant increase in shoot and root dry matter. It is necessary to check these results in future inoculation trials using soil as substrate and under field conditions.