Past and future changes in potato production vulnerabilities in Maine, U.S

Maine's favorable climate for potato growth has been threatened by the changing climate as an unprecedented drought in 2020 resulted in a significant reduction in yield. This study investigated climate-induced vulnerabilities by conducting trend analysis for weather indices affecting potato growth, including daily minimum (Tmin) and maximum temperature (Tmax), length of dry spells, heatwave duration, several temperature thresholds critical to tuber quality, and tuber initiation. A crop simulation model was used to translate the climate data into more practical information for growers' decision-making and climate change adaptation associated with irrigation water requirement. This study confirmed the occurrence of increasing trends in the historical temperature record, particularly nighttime temperatures and heatwave duration, especially in Aroostook County, Maine's potato heartland. The increasing temperature was associated with higher probability of exceeding optimal temperature ranges, in excess of 20 °C, for potato tuber growth. To maintain current yields, growers will need to use more water for irrigation. Increasing temperatures make potatoes less water-efficient, offsetting the benefits of CO2 fertilization. Future climate change scenarios revealed that potatoes will experience more heat-stressed days (Tmax > 32 °C) and stretches of sub-optimal temperatures by mid-century. Possible planting dates will shift 2–9 days earlier compared to historical averages. The irrigation water requirements will increase by up to 19% in the mid-century to meet potential potato production in the future. These results indicate that developing long-term strategies for managing agricultural water resources and improving water use efficiency are crucial to mitigating future vulnerabilities in Maine's potato industry. Highlights • Due to the warming climate, irrigation water requirements have, and will continue, to increase by the Mid-century. • Water use efficiency has decreased due to increasing temperature and ET. • The benefits of elevated CO2 for WUE have declined because temperature increases exceed the optimal growth range. • Despite the humid climate in Maine, irrigation is critical to maintaining sustainable potato production.