Abstract:

This research aims to investigate the optimum sowing date of soybean in frigid region under the background of climate change. Based on the daily average temperature and minimum temperature from 1971 to 2018 and daily average ground temperature at the soil depth of 0~5 cm from 1971 to 2015 of 140 meteorological stations in the frigid region, the temporal - spatial distribution of the first date of the temperature reaching 8℃, 0~5 cm ground temperature reaching 8℃, 9℃, 10℃, and the variation of ≥10℃ accumulated temperature were analyzed. The trend of the first date for temperature reaching 8℃ was clearly ahead in recent 48 years. While the first date of 0~5 cm ground temperature reaching 8℃, 9℃ and 10℃ advanced. The largest advance of the first date of 0~5 cm ground temperature reaching 8℃, 9℃ and 10℃ was in the four eastern leagues (Hulun Buir, Hinggan League, Tongliao and Chifeng of Inner Mongolia), and the smallest was in Liaoning. The first date of temperature reaching 8℃ and 0~5 cm ground temperature reaching 8℃, 9℃ and 10℃ were postponed from south to north in space, and the first date in Liaoning was the earliest, followed by that in Jilin and south of the four eastern leagues, and was relatively late in Heilongjiang and the north-central of the four eastern leagues. 0~5 cm ground temperature reaching 9℃ could be regarded as the agro-meteorological index of sowing date in Heilongjiang, Jilin and Liaoning, while 0~5 cm ground temperature reaching 10℃ could be used as the index of sowing date in the four eastern leagues. The spatial optimization of sowing date for soybean which combines agro-meteorological with variety maturity is critical for production layout against climatic change.

Key words: soybean, air temperature, ground temperature, sowing date, frigid region