Trend Analysis of Typical Phenophases of Major Crops Under Climate Change in the Three Provinces of Northeast China

【Objective】 The objective of this research is to analyze the phenophases(including the stages of seeding,heading and maturity) changes of rice,maize,spring wheat and soybean in three provinces of Northeast China.【Method】Annual slope change rate(θ) was computed to evaluate the temporal trend and the relationship between agroclimate and phenophases.【Result】Over the past 20 years,the timing of first effective temperature date(T≥10℃) was advanced,the first frost date was postponed,the growth period was continually extended and the accumulated temperature(T≥10℃) was increased in most area of the three provinces.Under this background,the temporal trend of phenophases of both rice and maize showed an advanced seeding stage(0.04θ0.55 d?a-1 and 0.04θ0.35 d?a-1),a postponed maturity stage(0.09θ0.35 d?a-1 and 0.23θ0.38 d?a-1) and an extended length of growth period(0.31θ1.26 d?a-1 and 0.11θ0.57 d?a-1).By contrast,temporal trend of soybean phenophases was different and characterized by an advanced seeding stage(0.01θ0.61 d?a-1),a maturity stage(0.18θ0.19 d?a-1),and a shortened growth period(0.06θ0.17 d?a-1).As for spring wheat,there was no obvious temporal change for the phenophases.【Conclusion】Climate change resulted in the increase of temperature suitability for crops,which could benefit from an early seeding stage,a late maturity stage and a long growth period.