Understanding yield gap and production potential based on networked variety-density tests and Hybrid-Maize model in maize production areas of Inner Mongolia Research advance in yield potential and yield gap of three major cereal crops Status and perspective of crop yield gap Determining the effects of climate on winter wheat yield in Northern China via yield gap analysis-A case study of Luancheng County, Hebei Province Change of Rice Yield Gaps and Influential Climatic Factors in Southern China