Mechanical grain harvesting is the development direction of maize harvesting technique, however, under a crop rotation system of winter wheat and summer maize, which is hardly to be achieved in China, resulting from insufficient heat resource in limited growing season for maize. So far, the northern Huang-Huai-Hai area is the area where the mechanical grain harvesting for maize is most difficult to be applied and spread all over the world. Thus, a study on the feasibility of corn’s mechanical grain harvesting is considerably significant to the whole-process mechanization, quality, proceeds and industrial competitiveness of corn production in Huang-Huai-Hai area.

In northern Huang-Huai-Hai area, the dynamic observation for the accumulated temperature requirements for grain dehydration of 5 maize cultivars with different physiological maturity, including Zhengdan958, Xianyu335, Dika517, Jingnongke728 and Fengken139, were designed in Xiangxiang, Henan province from 2016 to 2017 and then in Beijing, in 2018 respectively. Then, based on the meteorological data from 2007 to 2018, after reserving 500 ℃·d for winter wheat growth, the northern Huang-Huai-Hai area was divided into 7 accumulated temperature zones according to a temperature gradient of 100 ℃, so as to spatially illustrate the heat resource distribution during maize growth season in this area. Hence, the different cultivars’ accumulated temperature requirements for grain dehydration were mapped under the heat resource distribution in this area.

Under the conventional sowing condition of summer maize, each cultivar’s coverage that mechanical grain harvesting could be achieved after physiological maturity, with the advance of maturity, which were gradually extended northwardly, commonly 5-10 d later than the current sowing time for winter wheat in northern Huang-Huai-Hai area. However, the heat resource of accumulated temperature zonesⅠ-Ⅲ (1 900-2 800 ℃·d) were still hardly able to meet the requirements of Jingnongke728 and Fengken139 for a relative earlier physiological maturity than other 3 tested cultivars, not to metion reaching a grain moisture content of 25%. When the double cropping per year (winter wheat-summer maize) was reformed into the triple cropping per 2 years (summer maize-spring maize-winter wheat), the grain moisture content of all the tested cultivars, no matter planted in spring or summer, could reach 25% even less, achieving mechanical grain harvesting. Besides, for early-matured cultivars, by drying in filed and delaying harvesting, their moisture content might reach below 20% before winter wheat’s sowing, thus not only elevating harvesting quality, but also cutting drying costs.

In Northern Huang-Huai-Hai area, the problem, hindering maize production that insufficient heat resource in limited growing season issues in the difficult achievement of mechanical grain harvesting, could be effectively solved by reforming the current cropping system. Meanwhile, it also might provide a new horizon with theoretical foundation for the application of maize mechanical grain harvesting, further improving the quality and efficiency of maize production in Northern Huang-Huai-Hai area.