Spatial–temporal characteristics and influencing factors on the crop-growing period in the continental-temperate climate of Hexi Oasis

Based on the daily average temperature data at six meteorological stations in the crop distribution area of Hexi Oasis in Gansu Province during 1960–2019, the spatio-temporal characteristics and influencing factors of the temperature-related crops of 0 °C lower limit in the continental-temperate climate of Hexi Oasis was analyzed. The results showed that there were significant differences in the spatio-temporal changes in the climate growth period of the crops in Hexi Oasis. Over the last 60 years, the start date was advanced, the end date was postponed, the duration of the growing period was prolonged, and the effective accumulated temperature (EAT) was gradually increased. The tendency rates of start date, end date, and duration were − 1.752 days/10a, 1.734 days/10a, 3.486 days/10a, and 91.381 °C/10a, respectively. For the spatial variation, a trend of decreasing from southeast to northwest was observed, except for Yongchang which exhibits the highest elevation and lowest temperature. The M–K test showed that the end date of the crop growth period was most sensitive to climate warming, whereas the start date was least sensitive. Wavelet analysis showed that the start date, end date, and duration of the growing period of Hexi Oasis were mainly affected by atmospheric circulation (2–4a) and El Niño (2–7a), while the cycle of EAT agrees well with the sunspot activity cycle (11a). In addition, correlation and regression analysis showed that the variations of climatic crop-growing periods in Hexi Oasis are mainly affected by atmospheric circulation factors, followed by the monthly average temperature of the crop growth period and finally the geographic parameters including latitude and altitude. Furthermore, among the atmospheric circulation factors, West wind index (WCI) and Asian zone polar vortex area index (APVAI) are the major factors that affect the start date of crop climate growth period in Hexi Oasis, while the end date, the duration of the growing period, and EAT are mainly affected by carbon dioxide emissions (CDE), followed by APVAI, WCI, and Qinghai-Tibetan Plateau Index (TPI). This study would provide scientific supports for the development of crop security and the improvement of the ability of crops (e.g., spring wheat and maize) in Hexi Oasis to cope with climate change.