Effects of Non-host Plants on Growth of Mycorrhizal Fungi of Radiata Pine

Abstract

SUMMARY In view of the general absence of ectotrophic mycorrhizal fungi for radiata pine (Pinus radiata D.Don) from grassland soils, but their frequent occurrence in eucalypt soils, effects of non-host plants on mycorrhizal fungi were studied. In glasshouse experiments, grasses grown in association with pines depressed mycorrhiza infection, probably due to grasses lowering the nutrient status of the soils. ‘After harvesting of grass tops and replanting with Pinus radiata, decomposing grass roots decreased mycorrhiza formation. The data suggest production of toxins to mycorrhizal fungi from decomposing grass roots.’ Rhizopogon luteolus colonised sterile roots of the non-host plants, Lolium perenne, Phalaris tuberosa, Eucalyptus leucoxylon, E. camaldulensis and, to a lesser extent, Trifolium subterraneum. The growth of mycorrhizal fungi in the rhizosphere of nonhost plants may be important in the establishment and survival of mycorrhizal fungi in the absence of host plants.