Isoodon fusciventer (quenda) scat as a mycorrhizal inoculant and its effects on Eucalyptus gomphocephala (tuart) seedlings

Monique Smith

Tree declines, characterised by deteriorating tree health and increasing mortality, are a global trend with widespread consequences for the ecosystems involved. The tuart (Eucalyptus gomphocephala) is endemic to a narrow strip of coastline in south west Western Australia and is one of many Australian trees to have undergone a decline since European colonisation. Tuarts undergoing decline have fewer mycorrhizal associations than healthy tuarts. Mycorrhizal fungi associate with tree roots, improving water and nutrient uptake as well as offering some protection from root pathogens - all of which are factors associated with tuart decline. This study aimed to determine which source of mycorrhizal spores would be most effective at introducing mycorrhizal associations to tuart seedlings, and how the associations impact tuart health and growth. Three spore sources were used: ectomycorrhizal sporocarps, a commercially available product containing arbuscular mycorrhizae spores, and the scats of an opportunistic fungi-feeder - the quenda (Isoodon fusciventer). Tuart seeds were planted with inoculants containing all three spore sources, two of which had been autoclaved to kill spores. Thus each treatment only received active spores from one source. They were compared to two control treatments: one that received no inoculant (‘contaminant control’), and another that received an inoculant where all three spore sources had been autoclaved (‘nutrient control’). The treatment with live quenda scat spores had significantly more seedlings with ectomycorrhizal and arbuscular mycorrhizal colonisations than any other treatment/control. Neither the sporocarp or commercial treatment differed from the two controls in terms of seedling colonisation. The quenda scat treatment also exhibited less stress and fewer foliar symptoms of nitrogen deficiency, in a glasshouse environment. Finally, the scat treatment had smaller biomass and height compared to the nutrient control, although it still out performed the contaminant control in these measures. This study demonstrates that inoculation with quenda scats can successfully introduce ectomycorrhizal and arbuscular mycorrhizal associations to tuart seedlings. Increased mycorrhizal colonisations can result in traits, such as increased nutrient absorption, that are desirable for tuarts intended for restoration plantings. Further research is needed on the long-term growth and health of scat-inoculated tuart seedlings in the field.

Isoodon fusciventer (quenda) scat as a mycorrhizal inoculant and its effects on Eucalyptus gomphocephala (tuart) seedlings

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