Effect of actinobacteria on Lotus tenuis - Mesorhizobium loti symbiosis: preliminary study

The effect of the actinobacteria on the legume Lotus tenuis, a model forage plant of the Flooding Pampa region in Argentina was to promote plant growth and root nodulation. L. tenuis seedlings were inoculated either with the symbiotic N-2-fixing strain Mesorhizobium loti, or with saprophytic strain of Streptomyces MM40, Actinoplanes ME3, or Micromonospora MM18, or co-inoculated with a combination of one, two or three of them, together with the rhizobium. The plants were grown in pouches and fertilized with three nitrogen levels (low, medium and high). L. tenuis plants co-inoculated with the symbiotic M. loti and actinobacteria showed an increase in plant biomass and nodulation. Plants fertilized with high N levels (inhibitory for nodulation by M. loti) were nodulated if the M. loti strain was added simultaneously with actinobacteria. These preliminary results show that actinobacteria have potential agronomic application which should be further explored.