The possibility of predicting solute uptake and plant growth response from independently measured soil and plant characteristics

Summary

The growth and nitrate uptake characteristics of rape plants grown in soil at initial NO₃ ⁻ concentrations of 1.54×10⁻² M and 3.72×10⁻³ M are compared with those observed in solution culture at 10⁻² M and 10⁻³ M.

The relative growth rates and total nitrogen concentration of the soil grown plants were similar to those observed in solution culture. This suggests a remarkable capacity of the plant to regulate the size and efficiency of the photosynthetic and uptake machineries. Variations in the unit leaf rate or nitrate inflow in response to the environment or the internal nutrient status are counterbalanced by variations in the leaf area ratio or in ‘root length ratio’ so as to maintain a similar course of growth.

The shoot: root ratios and the root length per unit dry weight varied within similar ranges in soil and solution. The soil grown plants accumulated N preferentially in shoots compared with those grown in solution.