Abstract: Based on established climatic suitability assessment model and the 1981-2010 daily climatic data, and under the support of geographic information system, a simulation of optimum seeding date of spring maize was carried out in 1km grid mapping unit. The experimental results showed that optimum seeding time is at the third ten days of February in the south of and at the first ten days of Match in most part of middle and north of Hunan province. The optimum seeding time of mountain area gets later along with the height increase. According to the difference between the optimum seeding time and the earliest seeding time, research area can be classified into three subregions: (1) the basin in the south where the optimum seeding time is 2 weeks later than the earliest seeding time. (2) High mountain subregion where the optimum seeding time comes 2~3 weeks later. (3) The other part where the optimum seeding time is identical with the earliest seeding time. The determination of optimum seeding time needs to take into consideration of damages from high temperature damage in maturing stage and the deficit of water in the later growth period, as they varies spatially, the optimum seeding time determination need to be analyzed for different site specifically.

Key words: Optimum seeding time of spring maize, Spatial distribution, Climatic suitability model, GIS, Hunan