A Review on Crop Yield Gaps and the Causes

Yield gap is the difference between actual yield and potential yield of a crop.Research on yield gap is to survey the magnitude and regional variation of crop yield gaps,analyze the causes and seek measures to narrow or close the gap.Yield gap means the chance for agricultural development.Understanding the magnitude of yield gap and potential to increase crop yield is of great importance for improving food production to meet the growing food demand.This paper firstly discussed the definition and methods of yield gap,and then presented yield gaps of wheat,maize,rice and soybean in the world and in China by literature study.Followed in third section,the factors and their contribution to the yield gap were identified,including meteorological hazards,crop species,water and nutrients,disease,pest and weeds,soil and crop management,and agro-technologies,as well as economic and policy factors.Finally,future research focuses of yield gaps were discussed.