VAM and phosphorus induced changes in the rhizosphere ecology of Anethum graveolens L.

The influence of inoculation with two VAM fungi, Glomus fasciculatum and G. macrocarpum, was observed on the root exudation patterns and the rhizosphe re mycoflora of Anethum graveolens. Inoculation with VAM fungi reduces the quantity of amino acids and carbohydrates in the exudate which in turn resu lt in quantitative and qualitative changes in the fungal population in the rhizosphere. On the countrary, the augmentation of phosphorus supply throug h addition of P fertilizers does not bring about similar changes in mycoflo ra. The role of VAM fungi is suggested in biocontrol of fungal pathogens, t hrough a mechanism other than increased P-nutrition.