Magnesium-content of Rhizobium nodules in different plants: the importance of magnesium in nitrogen-fixation of nodules.

Objective: Rhizobium bacteria induce nodules (tumors) in roots of leguminous crops that fix nitrogen (N2) from the atmosphere.

Methods: Trials were carried on in sterile perlite where two species of peas were grown hydroponically, and in two different soil types (brown forest soil and meadow silt soil), in a field where different leguminous plants were chosen for test plants: lupin, soybean, broad-bean, lentil and bean inoculated by Rhizobium bacteria. The Mg-content of the nutrient solution was higher than that of the control, but in the soil tests 1% Mg leaf fertilization was applied after bacterial inoculation. Number, weight and Mg-content of nodules were evaluated using an AAS method compared with the thick and thin hair/roots of the given plant.

Results And Conclusions: Our results clearly show that the Mg nutrition treatment increased the number of Rhizobium nodules and their Mg-content, resulting in increased N2-fixation and yield.