THE EFFECTIVENESS OF VESICULAR‐ARBUSCULAR MYCORRHIZAS IN INCREASING GROWTH AND PHOSPHORUS UPTAKE OF SUBTERRANEAN CLOVER FROM PHOSPHORUS SOURCES OF DIFFERENT SOLUBILITIES

Abstract

SUMMARYThe effect of inoculation, with a VA mycorrhizal fungus on growth and phosphorus uptake of subterranean clover was examined using three phosphorus sources with different solubilities. Mycorrhizas markedly increased growth and phosphorus content of tops at intermediate rates of phosphorus application for all sources.The effectiveness of phosphorus for plant growth for mycorrhizal plants relative to non‐mycorrhizal plants was the same for a water soluble source (superphosphate) and two insoluble sources (C‐grade Christmas Island rock phosphate and calcined Christmas Island rock phosphate). The effectiveness of phosphorus from each of the three sources for phosphorus uptake by mycorrhizal plants relative to non‐mycorrhizal plants was also independent of the solubilities of the phosphorus sources applied.At a given phosphorus concentration in tops, non‐mycorrhizal subterranean clover produced more dry matter than mycorrhizal clover supplied with superphosphate. Mycorrhizal and non‐mycorrhizal subterranean clover supplied with C grade rock phosphate had the same dry weight at a given phosphorus concentration in their tops.VA mycorrhizas increased zinc but not calcium uptake by subterranean clover.