Abstract: Fully mechanized maize production has been trending in China, and using agricultural machinery to harvest maize grains is the focus of the transformation of maize production methods. Grain moisture content is the main factor affecting mechanical kernel harvesting, which is mainly affected by the agronomic characteristics of maize, ecological meteorological factors at the late growth stage, cultivation and management practice and other factors. Northeast China (NEC) is one of the main maize production regions and is the most sensitive regions to climate change in China. Clarifying the climate suitability and suitable zones for mechanical maize kernel harvesting in NEC under future climate conditions can provide scientific basis for improving the mechanization level of maize production and realizing the fully mechanized maize production in the future. In this study, based on the predicted climate data of 2021−2060 under two greenhouse gas concentration scenarios of RCP4.5 and RCP8.5 (the radiation forcing levels will reach 4.5W·m−2 and 8.5W·m−2 by 2100, which representing medium and high emission scenario, respectively) and the growth period data of spring maize, the northern boundaries of climate suitable zones for mechanical kernel harvesting of currently widely planted 29 middle-late spring maize varieties were determined using the kernel moisture content prediction models, and further the multi-variety based climate suitable zones were analyzed for the future 40 years. The results showed that climate very suitable, suitable, moderately suitable and marginally suitable zones for mechanical kernel harvesting will extend from southwest to northeast in NEC. And among different varieties, the northern boundaries of climate suitable zones fluctuate from the southwest to the southeastern mountainous areas of Jilin province (Changbai, Donggang and Songjiang areas) and the northern high latitude areas of Heilongjiang province. Under RCP4.5 (RCP8.5) climate scenario, the very suitable zones for 50% and 80% of middle-late maturing spring maize varieties located in the southern part of Liaoning province (the western and southern parts of Liaoning province). The northernmost can reach 42.0°N and 41.0°N (42.8°N and 41.9°N) latitude, and the easternmost can reach 123.4°E and 123.3°E (124.5°E and 123.3°E) longitude, respectively. The areas account for 5.9% and 1.8% (11.2% and 5.9%) of the potential growing area of spring maize in NEC, respectively. Suitable zones located in the northern and central parts of Liaoning province (the northern part of Liaoning province and southwestern part of Jilin province), with the northernmost reaching 43.0°N and 42.7°N (44.8°N and 42.9°N) latitude, the easternmost reaching 124.7°E and 124.4°E (124.7°E and 124.5°E) longitude, and the areas accounting for 8.3% and 8.9% (4.7% and 6.6%) of potential growing area of spring maize, respectively. In the future 40 years, compared with the RCP4.5 climate scenario, the middle-late maturing varieties of spring maize under RCP8.5 climate scenario have stronger climatic suitability for mechanical kernel harvesting, but the climate very suitable and suitable zones under the two climate scenarios are both small. The climate suitable zones for mechanical kernel harvesting will differ greatly between varieties, so varieties with short growth periods and fast dehydration rates which are suitable for mechanical kernel harvesting should be selected to improve the quality and efficiency of mechanical kernel harvesting in the future.

Key words: Spring maize, Kernel dehydration, Mechanical kernel harvesting, Climate suitable zones, Climate change, Northeast China