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. © 1990 Kluwer Academic Publishers.