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[Objective] The aim is to explore the spatio-temporal law and mechanism of the coupling between com supply and demand in China, and to provide scientific basis for regulating regional grain supply and demand balance. [ Method] Based on the centralization index, barycenter model, spatial overlap and Moran index of spatial Lorentz curve, this research discussed the spatio-temporal pattern evolution and dynamic coupling process of maize supply and demand situation in China since 2000 from the overall and regional perspectives. [ Result] ( i) The total supply and demand of China's com achieved a tight equilibrium-overall loose-tight equilibrium transition. With 2015 as the turning point, com yield showed the characteristics of first increasing and then decreasing, and stabilized at 260 million tons. Com consumption showed a fluctuating upward trend, reaching 288 million tons in 2021. ( ii) The regional differences of com production and consumption showed an expanding trend, and the geographical aggregation characteristics were continuously enhanced. The centralization degree of the supply area was higher than that of the consumption area. ( iii) The gravity centers of com production and consumption showed a trend of northeast migration, and the track had obvious stage characteristics. The distance between the gravity centers of com production and consumption showed a dynamic change process of deviation, fluctuation and convergence. ( iv) There was a significant positive spatial correlation between maize production and consumption in China, but the maize production and consumption in different provinces showed distinct spatial agglomeration characteristics. [ Conclusion] The spatial matching of China's com supply and demand was enhanced year by year, and its coupling characteristics changes were consistent with the changes of residents' consumption structure, agricultural production policies and the development process of industry and animal husbandry. [ABSTRACT FROM AUTHOR]

【Objective】It is of great practical significance to study the evolution characteristics and influencing factors of the temporal and spatial pattern of production in the major grain-producing counties for a comprehensive understanding of food security issues and the formulation of regional differentiated food polices. 【Method】Taking the 90 major grain-producing counties in Sichuan province as the research object, with the help of geographic gravity center model, spatial autocorrelation analysis, logarithmic mean dyadic decomposition method, the present study analyzed the spatial-temporal evolution characteristics and its influencing factors of grain production in Sichuan province from 2005 to 2020. 【Result】(i)From the perspective of comprehensive grain production capacity, the output of 90 major grain-producing counties in Sichuan province showed a stable growth trend, with an annual growth rate of 1.24%, but the fluctuation of grain production in different regions was different;(ii)From the perspective of different grain varieties, the variety that contributed the most to the increase of grain production in the 90 major grain-producing counties was maize, then followed by rice, potato and bean, and the contribution rate of wheat to grain yield was negative;(iii)From the perspective of spatial agglomeration characteristics, the gravity center of grain production of the 90 major grain producing-counties in Sichuan province moved to east and south as a whole, and the grain production capacity in the eastern region was generally higher than that in the southern region; Meanwhile, as time went by, the overall spatial agglomeration of grain production was gradually enhanced, high value agglomeration areas were mainly distributed in southern Sichuan economic zone, while low value agglomeration areas were mainly distributed in Chengdu plain economic zone and Panxi economic zone;(iv)From the perspective of influencing factors of grain yield increased, the increase of grain yield per unit area contributed significantly to grain yield increase, but the effect of the change of sowing area on grain yield in different regions was obviously different. 【Conclusion】It is suggested to strictly abide by the red line of cultivated land, strengthen scientific and technological support, improve the socialized service system for agricultural production, and establish a benefit compensation mechanism for major grain-producing counties of food production, so as to ensure the grain safety in Sichuan province. [ABSTRACT FROM AUTHOR]