辽宁省玉米适宜播种期的热量资源分析

适宜的播期是实现作物高产的必要条件。本研究基于辽宁省40个气象站历史气候数据，从玉米成熟所需的热量资源角度出发，提出了一种确定玉米最迟播种期的方法，通过对玉米播种开始日期、最迟播种期的计算，对30年（1971-2000年）玉米播期的时间变化特征和空间分布差异进行了分析。结果表明：辽宁省大部地区玉米播种的开始日期在4月中旬末至4月下旬。30年中，玉米播种开始日期全省总体的变化趋势不明显，仅辽东和辽北地区玉米播种的开始日期有提前趋势，约每10年提前2天左右。30年中辽宁各地初霜冻日均表现出延迟的趋势，全省平均变化趋势为1.6 d?10a-1。各地玉米的最迟播种期均在5月上旬末至5月中旬初，初霜冻日的推迟加之气候变暖趋势使得玉米最迟播期的气候倾向率为4.0-5.0 d?10a-1。本研究给出了辽宁省各县（市）适播品种、适宜播种的时段分布并提出了适宜播种期确定的建议，以期为农业生产提供一定的参考。

Analysis of the Thermal Resources for Optimized Planting Date of Maize in Liaoning Province

Optimized planting date is necessary for field crops to obtain the highest yields. From the perspective of the thermal resources required by maize maturity, this paper introduced a method to determine the latest planting date. Based on the weather station temperature data, the beginning date to plant, latest planting date as well as the spatial-temporal changing characteristics of the maize planting date during 1971 to 2000 were investigated. The results showed that for the most parts of Liaoning province the beginning date to plant was during mid-ten-day in April to last-ten-day in April. During the 30 years, the trends of the beginning day to plant for the whole province was not prominent except for the east and the north part of Liaoning Province showing earlier at a rate of 2 d/10a. The trends of the first frost date showed delayed in Liaoning Province and the average changing rate was 1.6 d/10a. The latest planting date was during the end of first-ten-day in May to the beginning of mid-ten-day in May. The delay of first frost date combined with climate changing warming made the rate of climate trends of latest planting date was 4.0～5.0 d/10a. At last, the adaptable breed and the time range for optimized planting of each district in Liaoning province were listed in this paper, which may provide a reference in field crop production.