Abstract: A method and apparatus are disclosed for assessing gas exchange of plants. The method includes receiving in a gas analyzer a plurality of test air samples from a leaf chamber corresponding respectively to first and second plant leaf samples received separately and in sequence in the leaf chamber while being exposed to light to form the first and second test air samples, the first and second test air samples being received in sequence in the gas analyzer as an integrated gas stream, and the gas analyzer analyzing the integrated gas stream as it flows therethrough. The measuring apparatus includes a leaf chamber for receiving therein a plant leaf sample to be tested, a pump communicating with the leaf chamber for supplying air thereto, and an analyzer communicating with the leaf chamber for receiving air therefrom and for analyzing the air received.