Nitrate Nutrition of Maritime Pine (Pinus pinaster Soland in Ait.) Ectomycorrhizal with Hebeloma cylindrosporum Romagn

In maritime pine seedlings (Pinus pinaster Soland in Ait.), nitrate absorption and reduction capacities were estimated by the incorporation of15N-labelled nitrogen. This method allowed us to work on the whole plant without perturbing plant behaviour. For this purpose, xylem and phloem transports were quantified. After 48 h of nitrate nutrition, mycorrhizal symbiosis with Hebeloma cylindrosporum Romagn. modified neither nitrate accumulation nor absorption and reduction capacities of this anion. Xylem transport of reduced nitrogen was similar in mycorrhizal and non-mycorrhizal seedlings. Only phloem transport was modified by mycorrhizal symbiosis. The intensity of the phloem transport in mycorrhizal pines was approximately twice that in nonmycorrhizal plants.