The Distribution and Abundance of Vesicular Arbuscular Endophytes in Some Western Australian Soils

Abstract

The distribution and abundance of large-spored vesicular arbuscular (VA) endophytes was examined at three localities in Western Australia. Within each locality, soil samples were collected from sites with a range of soil properties and superphosphate histories.

Vesicular arbuscular endophytes were widespread. Spores were found in all but five of 104 samples. In two of the samples where spores were not found, plants grown in the soils formed VA mycorrhizas. Root infection by a fine endophyte resembling Rhizophagus tenuis was also frequently observed.

Five spore types were found. Honey-coloured sessile spores were present in 85% of the samples. The yellow vacuolate spore type was the second most common endophyte, but its distribution was mostly limited to cultivated and fertilized soils. Endophytes other than the yellow vacuolate spore type occurred on both virgin and agricultural soils. The distribution of honey-coloured sessile and yellow vacuolate spores in cultivated soils appeared to be associated with variation in soil pH.

The total numbers of spores collected on a 106 μm sieve were not correlated with soil pH, NaHCO₃-extractable phosphorus or superphosphate history.