Nutrient Uptake and Supply to Tomato Plants in a Water Culture System 1

In horticulture a wide variety of soilless culture is in use. Among them is water culture. In order to provide a quantitative approach for fertilization policy, the kinetics of K⁺, NO₃⁻, and O₂ uptake by tomato (Solanum lycopersicum ‘Naama’) plants in a water culture has been investigated. A solution for a one-dimensional time-dependent model is given. Experiments were conducted in 3-m long channels of a homogeneous nutrient solution. Predicted results agreed with the measured data. For cases in which the Michaelis-Menten inhibition factor is much smaller than the initial ion concentration, the time dependence of the depletion curve can be approximated by a linear form, which when expressed in terms of dimensionless variables is the same for all ions. The model suggests an algorithm for a number of decisions that should be taken through the process of fertilization. Finally, when extended to the use of saline water under evaporative conditions, the model determines explicitly the worst quality irrigation water that can be used.