corn heat unit (CHU) are used in Canada to rank corn (Zea mays L.) hybrids for maturity; however, maps showing expected CHU during the growing season have not been updated since 1976. The objective of this study was to: (a) examine historical weather data for the Canadian Prairie provinces and determine if there has been a change in the annual accumulation of CHU (ΣCHU), and (b) use updated technology and improved access to weather data to revise ΣCHU maps. Daily temperature data, recorded over the past century at 8,750 weather stations across Canada and consolidated into 1,413 sites were downloaded. There were 466 sites in Alberta, Saskatchewan, and Manitoba. The daily CHU were summed over the growing season for each site by year. The annual growing season for corn in the Prairies increased by 3–12 d over the past century, with greatest increases in southern and western locations. The change coincided with warmer springtime temperatures, allowing for earlier seeding, and warmer autumn temperatures, allowing for delayed harvest. During the past century, ΣCHU increased by 200–400 depending upon location, and the area with ΣCHU suitable for growing corn for silage has more than doubled to 915 thousand km² (46% of the total area). These results provide tangible proof of climate change and its impacts on the potential for growing corn on the Prairies. The new ΣCHU maps can help farmers select regionally adapted corn hybrids. This study demonstrates the need for adaptive strategies for climate change in agriculture.

中文翻译：

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气候变化对加拿大草原省份玉米热量单位的影响

玉米热量单位（CHU）在加拿大用于对玉米进行排名（Zea maysL.）杂种的成熟度；但是，自1976年以来，未更新显示生长季节预期CHU的地图。本研究的目的是：（a）检查加拿大草原省的历史天气数据，并确定加拿大的年度蓄积量是否发生了变化。 CHU（ΣCHU）和（b）使用更新的技术并改进了对天气数据的访问以修改ΣCHU地图。下载了上个世纪在加拿大8,750个气象站记录的每日温度数据，并将其合并到1,413个站点中。在艾伯塔省，萨斯喀彻温省和曼尼托巴省有466个地点。在每个季节的生长季节中，按年对每天的CHU进行汇总。在过去的一个世纪中，大草原地区的玉米年度生长季节增加了3–12 d，南部和西部地区的玉米增幅最大。该变化与春季温度升高（允许播种较早）和秋季温度升高（允许延迟收获）相吻合。在过去的一个世纪中，ΣCHU随位置增加了200–400，适合种植青贮玉米的ΣCHU面积增加了一倍以上，达到91.5万公里^2个（占总面积的46％）。这些结果为气候变化及其对大草原上玉米种植潜力的影响提供了切实的证据。新的ΣCHU地图可以帮助农民选择适应当地情况的玉米杂交种。这项研究表明，需要针对农业气候变化采取适应性战略。