Interactions of cultivars, commercial strains of Rhizobium meliloti and fungicides on the production of alfalfa

The cultivation of alfalfa (Medicago sativa) is not only important because of its nutrient, content, but also for its high productivity and its abilit y to fix nitrogen through its association with Rhizobium meliloti. To bette r understand this symbiotic association, the interaction between R, melilot i strains SEMIA-116, SEMIA-134 and SEMIA-135 with different cultivars of al falfa Florida 77, Pioneer 5929, CUF 101 and Crioula was evaluated. In addit ion to the above treatments, the fungicides Iprodione and Thiram were used with the cultivar Crioula to study their effects on the alfalfa/Rhizobium i nteraction. Plants inoculated with SEMIA-116 had a greater number of nodule s. However, no significant difference in the production of plant dry matter was observed between the various Rhizobium strains and the alfalfa cultiva rs tested. In the presence of the tested fungicides, the Crioula/SEMIA-116 association showed superior biomass production and number of nodules. Resul ts obtained in this study suggest that SEMIA-135 should not be used as an i noculum for alfalfa when Iprodione is used either as a soil or seed treatme nt.