USE OF A SIMPLE DYNAMIC MODEL TO INTERPRET PHOSPHATE RESPONSE OF PLANTS GROWN IN SOLUTION CULTURE

A previously published dynamic model of P uptake and plant growth was applied to 2 sets of solution culture data: those of Rorison for 2 contrasting wild species [Deschampsia flexuosa and Rumex acetosa] and those of Brewster, Bhat and Nye for onions. Apart from the logistic constants describing the growth curves of plants with adequate P, all other constants were independently obtained and assumed to be the same for all species. Plant weights, P concentrations and solution P concentrations are all resonably well simulated by the model for both experiments. The big difference in responsiveness between fast and slow growing species in Rorison''s experiment is attributable to differential depletion of the solutions. The use of simulation models which incorporate the depletion of the growing medium might be regarded as an alternative to attempting to eliminate depletion in such experiments.