A SIMPLE-MODEL FOR PHOSPHORUS UPTAKE KINETICS OF WHEAT SEEDLINGS

a simple model to compare and predict phosphorus (P) uptake behavior o f plants may be useful to agronomists. A predictive equation based on Michaelis-Menten kinetics was developed for this purpose. Kinetic para meters for use in the model were determined in an experiment using two cultivars of winter wheat grown for 21 days in 14 soil treatments, in cluding seven P levels, each in fumigated and unfumigated soil. In ano ther experiment, the same wheat cultivars were grown for 7, 14, or 21 days at one soil P level in both fumigated and unfumigated soil. Using parameter values developed in the first experiment with multiple P le vels and one time period, the model closely (R(2) = 0.966, P < 0.001) predicted P uptake in the second experiment with one P level over mult iple time periods. The model could be a useful agronomic tool because of its simplicity and because no data need be collected from artificia l growing conditions.