Soluble carbohydrates in roots of leek (Allium porrum) plants in relation to phosphorus supply and VA mycorrhizas

Leek plants (Allium porrum L.) inoculated with Glomus mosseae were raised on sterilized soil/sand medium amended with Ca(H₂PO₄)₂. H₂O to test the hypothesis that high concentration of soil P inhibits formation of vesicular-arbuscular (VA) mycorrhizas by reducing concentration of soluble carbohydrate in the root. When P supply was increased, from either P addition or VA mycorrhizal infection, there was initially also an increase in concentration of soluble carbohydrate in the root. At the concentration of soil P at which infection was reduced, concentration of soluble carbohydrate was at its maximum. Therefore the above hypothesis is discounted. An increased delay in infection establishment and a greater number of abortive entry points would suggest that high concentration of soil P reduces VA mycorrhizal infection by changing the anatomy of the root to make it resistant to fungal penetration.