Nitrate uptake and respiration in roots and shoots: A model

Respiration in plants is often divided into growth and maintenance components. From the growth respiration it is possible to estimate the efficiency of conversion of substrate to plant material. Analysis of recent experimental data on this basis suggests that the conversion efficiency is considerably lower in roots than in shoots, which conflicts with biochemical analysis. The conventional method for describing respiration data is developed to incorporate root activity and is applied to a set of experimental data. The model provides a means for estimating the respiratory cost of nitrate uptake and also a possible explanation for the inconsistency between experimental observations and theoretical analysis.