Effect of phosphoric rock on dual symbiosis of VA mycorrhizal fungi and Rhizobium trifolii on red clover

Fernando Borie B.1, Rosa Rubio H.1, Elvira Moraga P.1 y Alfredo Morales L.1

A typical Andisol of southern Chile was used for carrying out a pot experiment with the dual symbiosis VA-mycorrhiza and rhizobium. The soil was fertilized with rock phosphate (RP) and triple superphosphate (TSP) and inoculated with both a native VAM fungus strain (Glomus etunicatum CH 110), and a Rhizobium trifolii strain. Red clover (Trifolium pratense L.) was used as a host plant. Five shoot cuts were performed during the six months of the experiment and dry weights were recorded. At the end of the experiment yield, number of nodules, % VAM root infection and N and P movilized were determined. Results show that the best response was obtained with the VAM fungus addition and using RP as the P source. There was a close relationship between N and P movilized, number of nodules and % VAM root infection. From the results obtained it was demonstrated the synergic effect ofthe dual symbiosis occurring in soils derived from volcanic ashes. This is a favorable situation to better know the performance of the prairies of Southern Chile.

Keywords: red clover, VA mycorrhiza, Rhizobium trifolii, rock phosphate.
1 Universidad de La Frontera, Casilla 54-D, Temuco, Chile.