The Effect of Mycorrhizal Infection of Goodyera Repens and Its Control by Fungicide

Summary Studies of the orchid Goodyera repens Br. growing on agar media in association with its natural endophyte Rkizoctonia goodyerae‐repentis Constantin and Dufour showed that mycorrhizal plants of different developmental stages had significantly higher growth rates and level of P and N than did uninfected ones. Treatment of mycorrhizal plants with the fungicide thiabendazole stopped growth of external mycelium and caused a significant decrease in growth rate, P and N content, percentage infection and net assimilation rate. These results suggest that the mycorrhizal fungus enhances nutrient uptake and allows greater growth rates, a situation similar to that found in non‐orchid mycorrhizas.