Photosynthesis Under Field Conditions. XA. Assessing Sources and Sinks of Carbon Dioxide in a Corn (Zea maysL.) Crop Using a Momentum Balance Approach1

In a previous communication we described a meteorological method of assessing the vertical distribution of photosynthesis and respiration activity in a corn crop. The method, however, is tedious. Here we describe a much simpler method. Results indicate that all the leaves of a corn crop appear to follow the same near‐linear light response curve, at least above the compensation point. Below the compensation point, all leaves evidently respire very little.