Plant Population Density and Competition

Crops respond to plant population density modifying the characteristics of individual plants by changing the number and size of their organs. The yield response to density can be described mathematically by the “Law of Reciprocal Yield.” Mortality of individuals occurs when density is very high. The effect is more pronounced when environmental conditions are suitable (e.g., high fertility). Yield–density curves can be asymptotic or parabolic, although the latter may reflect the existence of an additional limiting factor (e.g., water or nutrients). In general, the spatial variability in plant population density leads to yield losses that are higher when the yield–density response is a parabolic curve.