中文摘要：

玉米是我国主要粮食作物之一，东北三省是我国春播玉米主产区。本文以东北三省72个气象台站1961年～2010年逐日气象数据和5个典型农业气象台站1981年-2010年春玉米发育期数据为基础，研究春玉米关键发育期与对应界限温度的关系，并分析了近50年来东北三省初霜日和品种布局的时空变化情况。研究结果表明．日平均气温稳定通过10℃初日和14℃初日分别与春玉米的播种期和出苗期关系密切，不同熟性品种差异不大；日平均气温稳定通过16℃终日和10℃终日、初霜日分别较当地春玉米乳熟期和成熟期晚，推迟的天数以中熟品种最少、晚熟品种最多、中晚熟品种居中；近50年内，东北三省的初霜日呈现出逐渐推迟的趋势，推迟天数在几天至十几天之间；不同熟性春玉米的种植北界逐渐北移东扩，春玉米不可种植区逐渐缩小，晚熟品种的种植区逐渐扩大。

英文摘要：

Maize is one of the main grain crops in China. Three provinces of Northeast China are the main areas of planting spring maize. It is important for spring maize to study the relationship between key growth stages and critical temperature and to analyze the impacts of climate change on cultivated patterns. In this paper, daily time series of meteorological variables during the period 1961-2010 at 72 stations and growth stages of spring maize during the period 1981-2010 at 5 typical agro-meteorological stations were jointly used to study the relationship between key growth stages and critical temperature. Meanwhile, characteristics of spatial and temporal distributions of first frost day and cultivated patterns were analyzed in three provinces of Northeast China for the past 50 years. Results show that there were close relationships between the first date of air temperature 〉10℃ stably and sowing date of spring maize, between 〉14℃ and seedling date, which did not have obvious differences for different ripening varieties. The end date of air temperature 〉16℃ stably was later than the milking date of spring maize. The end date of 〉10℃ stably and first frost day were later than the harvest date. The delay days were minimum for the midseason variety, maximum for the late variety, and moderate for the middle-late season variety. For the past five decades, the first frost day tended to be gradually delayed from a few days to ten days in the three provinces. Regions where the first frost day started before Day of Year （DOY） 255 moved northward, with their southern boundaries in the first ten years of the 21^st century shifting northward than those in the 1960s. Areas where the first frost day appeared after DOY 271 spread the whole Liaoning Province, Songnen, and Sanjiang Plain in the first ten years of the 21^st century. The potential cultivated northern boundary of spring maize moved northward and eastward gradually. Non-planting areas tended to be reduced, which were replaced by the early variety of