Elevation-dependent wheat yields variations under climate changes

A continuing warming trend has been revealed at most regions around the world during the last 60 years. In order to assess the impact of the climate change on crop production, it is necessary to study the impact of observed climate change on crop development. In this study, we compared the impacts of climate warming on growth and yields of spring wheat at different elevation in northwest arid region by using observation data obtained in Zhangye (representative low-elevation) and Minle (representative high-elevation) agricultural meteorological station from 1981 to 2020. We analyzed temperature and precipitation data to determine climate trends, also analyzed surface observation data and potential evapotranspiration(PET) from agricultural meteorological stations to determine phenology and yields of spring wheat. The relationshipsbetween spring wheat growth, yields and the temperature, PET were also examined by SPSS24.0. The results showed that the climate change patterns and their impacts in these two stations were diverse during the study period. Warmer climate trends were observed both in low-elevation and high-elevation region, but the magnitude of warming at high-elevation was greater than that of low-elevation. The response of phenology of spring wheat to climate warming took the form that the sowing date had advanced in high-elevation and the growth duration had shortened in these two stations. The growth duration would shorten by 7.2d at high-elevation and by 4.0d at low-elevation for each 1^oC rising in daily mean temperature during spring wheat growth, and the sowing date would advance by 0.04d for each 100m rising in elevation. However, the response of the yields of spring wheat were different in these two stations. The yields showed a trend of increasing first and then decreasing, at high-elevation, but the yields had decreased at low-elevation. Such response was related to the critical temperature—30.1 ^oC at high elevation, and which was related to PET at low elevation. In case the maximum temperature during the spring wheat growth was less than 30.1 ^oC, a rising in temperature would increase yields. When the maximum temperature was beyond 30.1 ^oC, then a rising in temperature would decrease yields at high elevation, the response of PET is similar in low elevation. The continuous increase in temperature in future may result in the maximum temperature of spring wheat growth period to exceed the critical temperature, thus leading to declining of spring wheat yields. So we expect that with the climate further warming, it will continuately impact spring wheat growth and yields in arid region, especially the negative influence at low-elevation region.