Estimating maize yield potential and yield gap with agro-climatic zones in China-Distinguish irrigated and rainfed conditions

Understanding yield potential (Yp) and yield gap (Yg) in current intensive maize (Zea mays L.) production is essential to meet future food demand with the limited resources. In this study, we used the agro-climatic zones (CZs) and the reference weather stations (RWS) buffer zones, together with the Hybird-Maize model to estimate maize Yp in the four maize-growing-regions of China under both irrigated and rainfed conditions. In irrigated maize areas, we got 70 RWS buffer zones, and total maize area in the RWS buffer zones covered 67% of the whole irrigated maize area. In rainfed maize areas, we got 106 RWS buffer zones, which covered 51% of the whole rainfed maize area. As a result, the average Yp was 14.2 t ha−1 and farmers have achieved 58% of Yp. The average water-limited yield potential (Yw) was 10.7 t ha−1 and farmers have achieved 65% of Yw. Further analysis for four maize-growing-regions showed that precipitation was a limiting factor for Yw to fully achieve Yp except in Southwest China (SW), whereas the average precipitation was more than 653 mm during maize growing season. The ratio between Yw and Yp (Yw/Yp) was 51% in Northwest China (NW), and around 80% in both Northeast China (NE) and North China Plain (NCP). The comparison of Yp in different regions showed the low Yp in NE was due to low temperature while Yp in both NCP and SW were limited by low solar radiation. In conclusion, our findings highlight the efficiency and importance to estimate Yp, Yw and Yg by the upscaling method with CZs and RWS buffer zones. Meanwhile, the comparison of Yp, Yw and Yg in different regions was important to improve maize production in future in China.