Nitrogen and water resources commonly limit crop yield increases, not necessarily plant genetics

Frequently, improved plant genetics is viewed as the path to increased crop yields. However, in this manuscript, we argue that yield increases most often result from a combination of improved genetics and increased availability of nitrogen and water resources. At this time, it is likely that resource availability is the main impediment to yield increase in many cropping systems. In developing regions, it appears that nitrogen availability limits crop yield. In developed regions, rainfall and water availability commonly impose a substantial constraint on further crop yield increase. Strategies are examined to enhance resource accumulation and use in cropping systems of the future.

► Historic yield increases associated with greater supply of nitrogen and water.
► Nitrogen for seeds needs to be accumulated in vegetative stage.
► Nitrogen accumulation in vegetative tissues limited by their storage capacity.
► Water use is quantitatively related to maximum yield.
► Yield in developed countries now often limited by water availability.