An Apparatus to Produce Gas Mixtures with Controlled CO(2), O(2), and Water Vapor Concentrations.

An apparatus to produce continuous gas mixtures for use in measurements of plant gas exchange is described. A wide range of CO(2) and water vapor concentrations can be provided and O(2) concentration can be varied from 0 to 21%. Changes in the concentrations of the components are accomplished conveniently, rapidly, and independently. With occasional adjustments, CO(2) and O(2) concentrations can be maintained to within +/- 1 mul/l and +/- 0.1%, respectively. Dew point of the gas mixture can be maintained to within +/- 0.05 C.