Decline in tuber number and weight of potato (Solanum tuberosum L) associated with drought in 2020 and 2021 in a humid region of eastern Hokkaido

The objectives of this study were to verify changes in potato tuber number and weight under climatic variations in a cool region in Japan. We investigated potato growth over a 3-year period from 2019, establishing plots with different planting times and maturity types. In 2020, early planting encountered dryness during the tuber formation period after sprouting, which significantly reduced tuber numbers. Temperature was identified as the main factor contributing to the annual variation in potato yield, largely due to unusually high temperatures during the study period. In 2021, hot and dry conditions in early summer (mid to late July) corresponded to the tuber bulking period and reduced the yield owing to light tuber weight regardless of the planting time and variety. The present study provided insights into the variability of yield components in potato by focusing on drought effects, weather, and cultivation factors, which vary substantially.