Impacts of Climate Change on the Major Growth Stage of Winter Wheat in Lhasa River Valley from 1996 to 2021

Understanding the impact of climate change on the growth period of winter wheat is helpful to provide a basis for agriculture to cope with climate change and adjust crop planting structure. Based on the data of winter wheat growth period and daily average temperature(T_m), maximum temperature(T_max), minimum temperature(T_min), diurnal temperature range (DTR), relative humidity(RH), precipitation(Pr), sunshine duration (S) and accumulated temperature above 0 ℃(∑T₀) et al. in Lhasa in the past 26 years (1996—2022), the variation characteristics of growth period for winter wheat and the dominant meteorological factors in Lhasa River Valley were analyzed by linear trend estimation, Pearson correlation coefficient and dominance analysis. The results showed that: (1) The T_m of winter wheat in vegetative growth period (VGP), reproductive growth period(RGP) and whole growth period(WGP) in Lhasa River Valley showed an upward trend in the past 26 years. The warming rate of T_min was greater than that of T_max, DTR and RH showed a decreasig trend, as well as Pr, S and ∑T₀ tended to increase. (2) Each growth period of winter wheat was advanced before jointing, with a rate of 0.47~6.75d/10 a. All growth period were delayed after jointing by a rate of 3.17~7.03d/10 a, which made VGP & WGP prolong, and RGP shorten. (3) The increase of T_min in October and January, and T_m in February was the major factor for the emergence, tillering and regreening of winter wheat in Lhasa River Valley. The important factors leading to the delay of the growth period of winter wheat after jointing were the increase of S from April to May and the decrease of RH in June.