Growth, Maintenance and Respiration: a Re-interpretation

Abstract

The traditional view of respiration being due to the processes of growth and maintenance is questioned. A model is proposed in which plant dry matter is divided into three categories: storage material which may be used for growth; non-degradable structural material which cannot be recycled, and which is considered to be inert; and degradable structural material which is assigned a rate constant of degradation, and which is considered to be biologically active. The model has four parameters: two yield constants, and two rate constants, and it has been solved for steady-state exponential growth in continuous daylight, respiration in the dark, and ^l4CO₂ evolution after a pulse label. Analysis of ^l4CO₂ efflux data leads to the complete definition of the model. The utility and comparative merits of the suggested viewpoint of respiration are discussed.