Possible influence ofRhizobiumon VA mycorrhiza metabolic activity in double symbiosis of alfalfa plants (Medicago sativaL.) grown in a pot experiment

摘要

Alfalfa (Medicago sativa, L. cv Aragón) plants were grown under greenhouse conditions in pots of inert sand and vermiculite. The plants were inoculated withRhizobium melilotistrain 102F28, withGlomus fasciculatusor with a mixture of both microorganisms. Plants inoculated with bothRhizobiumandGlomushad the highest shoot dry weight and the lowest root-to-shoot ratio. Roots from dually inoculated plants also had a higher oxygen uptake and nodule nitrogenase activity than those from plants inoculated with either of the two microsymbionts alone. However, the dry weight of the roots from only VAM-infected plants was higher than those fromRhizobiumor fromRhizobiumplusGlomus-inoculated ones. These differences did not correlate with succinate dehydrogenase activity, which was similar between treatments. Nutrient element concentrations were increased in dually infected plants in comparison with those of plants inoculated with onlyRhizobiumorGlomus. These data suggest thatRhizobiummay affect fungal metabolism and that the effect is not achieved via the tricarboxylic acid pathway