MYCORRHIZAL INFECTION AND AGING AFFECT ELEMENT LOCALIZATION IN SHORT ROOTS OF NORWAY SPRUCE [PICEA-ABIES (L) KARST]

Norway spruce [Picea abies (L.) Karst.] seedlings, nonmycorrhizal of m ycorrhizal with Laccaria laccata or Paxillus involutus were grown in a quartz sand-nutrient solution system for 6 months and then treated wi th 5 mu M Pb for 4 days. Element contents of cortex cell wall of young , medium and old short roots were determined by X-ray microanalysis of longitudinal thin sections. The Pb content was influenced neither by age nor by the distance from the root tip (up to 1.7 mm) but was signi ficantly lower in the P. involutus mycorrhizae than in the L. laccata mycorrhizae or in nonmycorrhizal short roots. In the P. involutus myco rrhizae, the P content of the cortex cell walls was twice as high in y oung mycorrhizae than in old mycorrhizae. In the nonmycorrhizal short roots and the L. laccata mycorrhizae, P content was influenced neither by age nor by distance from the root tip. The Ca and Fe contents of t he cortex cell walls increased with age in the nonmycorrhizal short ro ots and the mycorrhizae. It is concluded that the element content of t he cortex cell walls of short roots is strongly influenced by age, whi le the distance from the root tip seems to be of minor importance.