Impedance Parameters in Relation to Phosphorus and Calcium Deficiencies in Subterranean Clover (Trifolium subterraneumL.)

Abstract

Changes caused by separate calcium and phosphorus deficiencies in the impedance locus and associated parameters of petioles were investigated. In samples of mixed ages the deficiencies where characterized by a significant change in 17 out of the 18 parameters studied. Almost invariably the change caused by phosphorus deficiency was significantly greater than that caused by calcium deficiency. In a more detailed study of phosphorus deficiency it was found that there is often a signifi cant interaction between age and parameter change. From the phase angle data it is concluded that the plasma membrane ages more rapidly in deficient than in non-deficient plants; nevertheless the physico-chemical composition of the plasma membrane in newly formed cells is the same in deficient and non-deficient petioles of similar ages. A mathematical inference that phosphorus deficiency causes a lessened potassium uptake is confirmed experimentally.