Growth Responses of Endomycorrhizal Onions in Unsterilized Coal Waste

Summary The effects of the widespread vesicular‐arbuscular (VA) endophytes, namely Glomus macrocarpus var macrocarpus, Glomus mosseae, and Sclerocystis rubiformis and those of E3 (a strain of Endogone introduced from Rothamsted Experimental Station) on growth of onions were compared in unsterilized coal washery waste from the Coal‐Cliff Collieries in the Illawarra region of New South Wales. Mycorrhizal onions were significantly larger (P < 0.05), with respect to all the growth measurements than NM controls. Different VA endophytes had quantitatively different effects on the growth; the S. rubiformis was always poorest and E3 most consistently good. This is because S. rubiformis produced more localized infection, while the growth of E3 was more general producing, under similar conditions, more extramatrical hyphae than any other endophyte used. Among widespread species G. mosseae was the most efficient at stimulating plant growth. The possible role of VA mycorrhizas in plant colonization of coal spoil areas is discussed.