Photosynthesis under field conditions XA. Assessing sources and sinks of carbon dioxide in a corn(Zea Mays L.) crop using a momentum balance approach

In a previous communication we described a meteorolo-gical method of assessing the vertical distribution of pho-tosynthesis 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