Agronomy and Horticulture Department


Date of this Version



Published in Physiological Aspects of Crop Yield: Proceedings of a symposium sponsored by the University of Nebraska, the American Society of Agronomy, and the Crop Science Society of America, and held at the University of Nebraska, Lincoln, Nebr., January 20-24, 1969. Edited by Jerry D. Eastin, F. A. Haskins, C. Y. Sullivan, C. H. M. Van Bavel, and Richard C. Dinauer (Madison, Wisconsin: American Society of Agronomy & Crop Science Society of America, 1969). Copyright © 1969 American Society of Agronomy & Crop Science Society of America. Used by permission.


Recent work in this laboratory has been directed towards increasing net photosynthesis or decreasing the transpiration rate in higher plants by exercising biochemical control over these processes. In these experiments, the fact that both photosynthesis and transpiration involve diffusion processes that might be regulated by varying appropriate diffusive resistances has been exploited (Gaastra, 1959; Zelitch and Waggoner, 1962a). Since in most instances the pathway of diffusion of water vapor in transpiration is shorter than that of CO2 uptake in photosynthesis, and both gases must pass through the stomata, it was predicted that closing the stomata in a specific manner would diminish transpiration more than net photosynthesis.