A yield gap analysis for rapeseed (Brassica napus L.) is critical to meeting the oil demand by identifying yield potential and yield constraints. In this study, potential yield (Y p ), attainable yield (Y att ), and actual yield (Y act ) for winter rapeseed were determined in five different zones of China. A boundary line approach was adopted to calculate Y p , based on a large-scale field experimental database. A meta-analysis was conducted on the data obtained from 118 published studies to

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... luate the effects of agronomic factors on rapeseed yield. The main results indicated that farmers only achieved 37-56% of the yield potential across the zones. The low altitude areas (L-URY) and lower reaches (LRY) of the Yangtze River Basin (YRB), China had high yield levels. The total yield gap was 1 893 kg ha -1 , due to the agronomic management factors, environmental factors, and socioeconomic factors. The meta-analysis showed that weed control and drainage were the best management practices to improve yields (45.6 and 35.3%, respectively), and other practices improved yields by 17.1-21.6%. Consequently, to narrow the yield gap over the short term, the study could focus on techniques that are easily implemented to farmers. area was approximately 35 Mha in recent 10 years (FAO 2017). Asia, North America, and Europe are the major producing regions in the world. As a cool-season, broadleaf crop, rapeseed can be planted both in winter and spring (Assefa et al. 2018). The spring variety is mainly planted in Canada, where it was called canola and is partially planted in China, US, and European countries. The winter variety, which is called winter rapeseed, is widely planted in Asia, Europe, and US. Due to the different growing environment and management practices, the yield in Europe is much higher than that in China, Canada, and US (FAO 2019). It is noteworthy that China has contributed 20% of the global rapeseed production with 7.5 Mha of planting area (FAO 2019). More than 85% of this production is winter rapeseed that is sown in the late fall season and harvested in the early