Higher risk of spring frost under future climate change across China's apple planting regions

Abstract

Spring frost is one of major agro-meteorological disasters impacting apple production. Previous studies focused on the impacts of spring frost during the flowering period on apples, however, the frost events occurring at both pre- and post-flowering phases have significant impacts on apples. Our study employed four phenology models (parallel model, M1 model, sequential model, and growing degree hour model), along with their ensemble model driven by five global climate models (GCMs) to predict the key spring phenphases of apple across China’s apple planting regions under two emission scenarios (SSP245 and SSP585) during the 2050 s (2040–2069) and 2080 s (2070–2099). A new spring frost assessment index (FI) combining frequency and intensity of spring frost was developed to evaluate the impacts of climate change on spring frost risk of apple. The results showed a large spatial variation in projected spring phenophases across China’s apple planting regions. Projected budbreak (BBCH 09), initial flowering (BBCH 60), and final flowering (BBCH 69) would advance 5.6–15.9 days, 5.7–14.8 days, and 5.6–14.5 days, respectively, in regions I, II, and V of northern China apple planting regions. However, in regions III and IV of southern China apple planting regions, projected budbreak, initial flowering, and final flowering would delay –9.2–21.5 days, –7.5–20.6 days, and –6.8–20.8 days in the future climate scenarios, compared with the baseline (1980–2009). Projected last spring frost date considering the entire spring phenphases would advance 3.7–11.8 d in the future climate scenarios, compared with the baseline. Projected spring frost risk would increase in all the three growth stages including budbreak to initial flowering, flowering period, and final flowering to the last spring frost date across all the China's apple plating regions in future climate scenarios except southward China's apple plating region under the SSP585 in the 2080 s. Our study provides an important reference for early warning, prevention and mitigation of spring frost disasters, and the layout of the apple industry.