PHOSPHATE UPTAKE BY GOODYERA REPENS IN RELATION TO MYCORRHIZAL INFECTION

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Abstract
Summary: The rate of P uptake per unit length of root of adult plants of the orchid Goodyera repens Br., infected with the mycorrhizal endophyte Rhizoctonia goodyerae‐repentis Constantin and Dufour, was up to 100 times greater than that of non‐mycorrhizal plants. When the active extramatrical mycelium was reduced by treatment with thiabendazole fungicide, the relative growth rate of mycorrhizal plants was reduced in low P conditions but not in P rich conditions. Rates of P uptake into fungicide‐treated plants were Jess than those of mycorrhizal plants at both P levels. Translocation of 32P from a point source to the plant via the extramatrical mycelium was demonstrated and could be inhibited by the application of thiabendazole. In a model system incorporating a perlite/Vermiculite substrate, translocation of 32P via the endophyte took place over distances up to 9 cm. The mycorrhiza of adult G. repens appears similar to other mycorrhizas in its ability to enhance growth and P uptake.