Combined Impact of Climate Change, Cultivar Shift, and Sowing Date on Spring Wheat Phenology in Northern China

Distinct climate changes since the end of the 1980s have led to clear responses in crop phenology in many parts of the world. This study investigated the trends in the dates of spring wheat phenology in relation to mean temperature for different growth stages. It also analyzed the impacts of climate change, cultivar shift, and sowing date adjustments on phenological events/phases of spring wheat in northern China （NC）. The results showed that significant changes have occurred in spring wheat phenology in NC due to climate warming in the past 30 years. Specifically, the dates of anthesis and maturity of spring wheat advanced on average by 1.8 and 1.7 day （10 yr）-1. Moreover, while the vegetative growth period （VGP） shortened at most stations, the reproductive growth period （RGP） prolonged slightly at half of the investigated stations. As a result, the whole growth period （WGP） of spring wheat shortened at most stations. The findings from the Agricultural Production Systems Simulator （APSIM）-Wheat model simulated results for six representative stations further suggested that temperature rise generally shortened the spring wheat growth period in NC. Although the warming trend shortened the lengths of VGP, RGP, and WGP, the shift of new cultivars with high accumulated temperature requirements, to some extent, mitigated and adapted to the ongoing climate change. Furthermore, shifts in sowing date exerted significant impacts on the phenology of spring wheat. Generally, an advanced sowing date was able to lower the rise in mean temperature during the different growth stages （i.e., VGP, RGP, and WGP） of spring wheat. As a result, the lengths of the growth stages should be prolonged. Both measures （cultivar shift and sowing date adjustments） could be vital adaptation strategies of spring wheat to a warming climate, with potentially beneficial effects in terms of productivity.