An investigation of the usefulness of phosphorus concentrations in tissue water as indicators of the phosphorus status of field-grown spring barley.

The effects of recalculating P concentrations in spring barley (Hordeum vulgare L. cv. Georgie or Julia) on the basis of tissue water were investigated. Expressing P concentrations in this way altered their apparent behaviour with time. Whereas % P in dry matter declined during growth, P concentrations in tissue water decreased initially but then increased. The rate of increase became more rapid during senescence. Nitrogen and water supplies induced differences in % P in dry matter but these were reduced when P concentrations were expressed on the basis of tissue water. Like % P in dry matter, P concentrations in tissue water were lower in crops grown on a soil that had not received P since 1852. It is suggested that P concentrations in tissue water can provide a method for assessing crop P status that has some advantages over % P in dry matter