Analysis of Korean Rainfall Patterns and the Effects of Excess Soil Moisture on Water Transport in Table Grapevines During the Growing Season Under Experimental Conditions

Recent changes in rainfall patterns driven by climate change, including localized heavy rainfall, droughts, and prolonged rainy seasons, have significantly impacted grapevine growth and quality. An analysis of rainfall patterns in South Korea from 1995 to 2024 revealed that 54.5–58.0% of the annual average precipitation of 1357 mm occurs during the fruit enlargement period from June to August, at an average of seven consecutive days of rainfall, indicating a heightened potential for exposure to increased soil moisture stress for seven days annually. This study evaluated the physiological responses of grapevine cultivars ‘Campbell Early’ and ‘Jinok’ under flooding and excessive soil moisture conditions over a seven-day period. Both cultivars exhibited reductions in leaf (LWP) and stem (SWP) water potential, cumulative sap flow in the xylem (CSF), and photosynthetic rate (Pr) under flooding or excessive soil moisture conditions. At the same time, an increase was observed in the crop water stress index (CWSI) and relative leaf electrolyte leakage (REL). Several investigated parameters indicated impaired water uptake and transport under soil moisture stress conditions. Correlation analysis revealed that soil moisture was negatively correlated with the Pr and CSF, while it was positively correlated with LWP, SWP, REL, and CWSI. Our findings provide critical insights into the physiological responses of grapevines to rainfall variability and offer valuable guidance for future research in this field.