Short-term extreme heat at flowering amplifies the impacts of climate change on maize production

Extreme weather poses a threat to global crop production, food security and farmer livelihoods. High temperatures have been identified as detrimental to crop yields; however, how heat stress during the critical flowering stage will influence future maize (Zea mays L.) yields remains unclear. Here, we combined statistical and process-based models to assess impacts of short-term extreme heat at flowering on Chinese maize yield under climate change. We showed that heat around flowering has a stronger impact on yields than heat at other times in the growing season, especially for temperatures >30 & DEG;C. Heat stress during flowering was responsible for 23% of total yield loss from extreme degree days (EDDs) in 1990-2012. An improved process-based model (Agricultural Production Systems sIMulator (APSIM)-maize) incorporating a grain-temperature function was then applied and indicated that extreme heat at flowering amplified the impacts of climate change on maize production compared to the original model. The improved APSIM-maize predicted an 8.7% yield reduction across the Chinese Maize Belt as EDDs increased more than quadrupled at the end of the century (2070-2099) under a high emissions pathway (SSP585) in comparison with the baseline period (1990-2019). Our study highlights the importance of extreme heat at flowering on maize yield and can inform farmers and policy makers on adaptive measures as well as providing a reference for other crop areas facing similar challenges.

Automated summary

Extreme heat during the critical flowering stage has a significant impact on maize yield in China, and this effect is expected to be amplified by climate change. A process-based model incorporating a grain-temperature function predicts an 8.7% reduction in maize yield across the Chinese Maize Belt by the end of the century due to increased extreme heat. This study highlights the importance of addressing extreme heat at flowering for maize production and provides valuable insights for farmers and policy makers.