Vernon W. Ruttan
University of Minnesota

A combination of population and income growth will more than double the demand for food and other agricultural commodities over the next half century. Advances in crop productivity during the twentieth century have largely been based on the application of Mendelian genetics. If farmers are to respond effectively to the demands that will be placed on them over the next half century, research in molecular biology and biotechnology will have to be directed to removing the physiological constraints that are the source of present crop yield ceilings.

Key words: Biotechnology; physiological constraints; crop yield ceilings; mendelian revolution.