Simultaneous calorimetric and respirometric measurements on plant tissues

Abstract

Simultaneous measurements of the rates of heat production, CO 2 production, and O 2 utilization by living plant tissues provide a useful means of determining metabolic efficiencies and detecting and quantifying changes in the metabolic pathways active in the tissues. This paper describes a convenient, simple method for simultaneously measuring metabolic heat rate and the rate of CO 2 production directly in the calorimetric reaction vessel. The method requires only a slight modification of existing, commercially available, heat conduction calorimeters. Calorimetric measurement of the rate of heat production by reaction of CO 2 with a base is used to obtain CO 2 production rates. The detection limit for CO 2 production is 50 picomole/second, which is similar to the detection limits reported for commercially available respirometers of various types.