Increasing Photosynthesis: Unlikely Solution For World Food Problem

Increasing the photosynthesis rate of plants has been recently revitalized as an approach for increasing grain crop yields and solving world food crises. The idea that photosynthesis is the key to increasing grain crop yields is not new. Considerable research in the 1970s and 1980s showed that carbon input was not limiting for crop growth and yield. Instead, the availability and uptake of water and nutrients were found to be critical for increasing grain yield, and that conclusion still applies today. In this Opinion article, nitrogen limitation is given particular attention because of its quantitative linkage with vegetative and reproductive growth and its essential role as a quantitative component of seeds. Past crop yield increases are not associated with increased photosynthesis.Yield increases are closely dependent on nitrogen accumulation, which is an essential and quantitative component of seeds.Carbon accumulation in the absence of additional nitrogen does not increase yield.Yield increase requires greater nitrogen accumulation, plant nitrogen storage, and ultimate transfer to growing seeds.Research on nitrogen husbandry is critical for crop yield increase and environmental viability.