Studies on ectomycorrhiza - XXII. Mycorrhizal rhizomorphs of <em>Telephora terrestris</em> and <em>Pisolithus tinctoriu</em>s in association with Norway spruce (<em>Picea abies</em>): formation in vitro and translocation of phosphate.

Plants of Picea abies (L.) Karst were grown in mycorrhizal association with Telephora terrestris (Pers. ex Fr.) and Pisolithus tinctorius (Mich. ex Pers.) Coker and Couch on sphagnum peat in petri dishes or Perspex chambers. After 1 year T. terrestris had formed prominent rhizomorphs which were characterized by light microscopy and investigated for 32P-orthophosphate uptake. The absorbed phosphate was transported to sinks throughout the rhizomorphal system as well as into the plant. The calculated translocation velocity and flux rate in the rhizomorph were in the range of 1-3 cm/h and 0.5-4.0 &times; 10 -10 mol cm -2 s -1, respectively. Label was observed to accumulate in the needles 2-3 days after application. Feeding a non-mycorrhized root with 32P-orthophosphate led to an accumulation of label in needles within 1 h, but no radioactivity appeared in the associated T. terrestris rhizomorphs. The rhizomorphs of P. tinctorius revealed a higher structural differentiation than those of T. terrestris. Translocation of labelled phosphorus through rhizomorphs of P. tinctorius into spruce needles was also demonstrated