The effect of long-term applications of phosphorus fertilizer on populations of vesicular-arbuscular mycorrhizal fungi in pastures
1992
Thomson, B.D. | Robson, A.D. | Abbott, L.K. (Western Australia Univ., Nedlands. School of Agriculture)
In 1977, 4 rates of P were applied to a field site at Mt Barker, Western Australia. In 1983, either no P or a rate of P sufficient for maximum plant growth (352 kg per ha) was applied. Residual P from fertilizers applied in 1977 increased both the percentage of root length colonized and the length of root colonized by VA mycorrhizal fungi in 1983, 1984 and 1985. There was a common relationship between VA mycorrhizal colonization and the residual value of the P applications which provided indirect evidence that there was no change in the P-tolerance of the indigenous VA mycorrhizal population in response to P applied in 1977. Interpretation of the effects of the 1977 and 1983 applications of P on VA mycorrhizal colonization was compounded by the effects of these applications of P on the botanical composition of the pasture and also on the inoculum potential in each plot. Spores of Acaulospora laevis and Scutellospora calospora were recovered from each field plot. The number of spores of A. laevis increased in response to P applied in 1977 and generally decreased in response to P applied in 1983. These effects could be directly related to the effects the 1977 and 1983 applications of P had on the length of root colonized by A. laevis in the preceding growing season.
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