Understanding the Yield Gap in Wheat Production.

Wheat production around the globe is a staple of human nutrition needs and will continue to provide a major component of global food security. The increases in world population demand that we continue to increase wheat production in a sustainable manner. To achieve this goal requires we understand what limits wheat production and potential solutions to overcome these limitations. The framework for this approach is the use of yield gaps which we can define as either the difference between potential and actual yield or attainable and actual yield. Potential yields can be obtained through the use of computer simulation models while attainable yields utilize observed yields under non-limiting conditions. In this analysis, attainable yields are used because they account for changes in technology over the course of yield records. Yield gaps are a result of weather effect on growth and yield. Data collected throughout the globe indicate that for wheat production, rainfall variation is the primary factor affecting yield. In an analysis of Oklahoma, Kansas, and North Dakota wheat yields, rainfall during the grain-filling period was the dominant factor related to the yield gap. There are instances, in which high temperatures during grain-filling reduce yields; however, these effects are often associated with below normal rainfall amounts. Yield gaps provide a technique to assess the progress in utilizing technology to enhance production and continued use of this approach provides a framework for how to manage our crops for increased food security.