Abstract: The northern ecotone is an area sensitive to climate changes, and crop’s growth and development are profoundly affected by them. Studies on the impact law of climate change on agricultural production and crops’ response to climate change are of great significance to promote sustainable development of agriculture in the northern farming-pastoral ecotone. Based on the 1960-2009 meteorological data and 1992-2010 agro-meteorological observation data of spring wheat in Wuchuan County, the relationship between climate change and growth period changes of spring wheat were studied in this paper as a representative case of the northern farming-pastoral ecotone. It is shown that the annual temperature of Wuchuan County increased at an average rate of 0.43℃/10a in 1960-2009. The date to meet the spring wheat seeding temperature had an advanced trend. The first date for daily mean temperature in spring to steadily pass through 0 ℃ advanced 0.98 d/10a, the last date for daily mean temperature in autumn to steadily fall down through 0 ℃ postponed 0.24 d/10a, and thereby the growing season of spring wheat had an extending trend. The soil relative humidity in soil layers 0-10 cm and 10-20 cm depth in crop growing season (April-August) during the period 1992-2010 had a decreasing trend with an average rate of 18%/10a and 13%/10a, respectively. The first date of the sowing stage was significantly negatively correlated with the soil relative humidity of 0-10 cm and 10-20 cm depths, i.e., the soil relative humidity reduced every 1%, the first date delayed 0.2 and 0.3 d, respectively. The other growing stages were the same as sowing stage, affected by the combined effects of temperature and soil moisture, that is to say, duration days between various growth stages was positively correlated with temperature and soil moisture. It is concluded that changes in spring wheat growth period are the result of the combined effect of climatic factors, but in the northern farming-pastoral ecotone, soil moisture has a greater impact on crop’s growth and development, in particular, directly on all growth stage processes of spring wheat.

Key words: climate change, spring wheat, growth period, response, Wuchuan County