Effect of Soil Phosphorous Levels on Phosphate Fractions in Tomato Leaves1

Abstract

Abstract Varying the level of added P to a deficient soil from 0, 25, 50, 75, 100, 200 and 400 ppm made it possible to study the influence of deficiency, sub-adequate, adequate and excess amounts of P on its distribution into P fractions within tomato leaves. Plant growth response was obtained at P rates up to 100 ppm. The P fractionation data indicated that inorganic phosphate constituted about one quarter of the total plant P even when the plant is deficient in P. The plant did not accumulate phosphate until it was supplied at rates that exceeded requirements of growth and then it was accumulated mainly as inorganic phosphate while the levels of soluble organic P, RNA-P, DNA-P, phospholipid-P and phosphorprotein-P remained unchanged over the entire range of P rates.