This study quantitatively assessed the impacts of climate change and extreme weather events on the suitability zones and dry matter yield (DMY) of Italian ryegrass (Lolium multiflorum Lam.) in Korea. Baseline climate (2006–2015) and recent climate (2021–2023) conditions were compared using national meteorological and crop yield data. A significant decrease in total annual precipitation (−84.3 mm, p<0.001) was observed, while winter minimum temperatures showed a slight but statistically insignificant increase (+0.27°C, p = 0.111). Suitability zone classification based on agro-climatic zoning indicated regional shifts, particularly a decrease in the best suitable zones in 2021 and partial recovery by 2023. Dry matter yield increased by 31.6% in central Korea due to improved winter survival under warmer conditions, while southern Korea experienced a 9.4% yield reduction in response to a severe spring drought in 2022. Pearson correlation analysis showed a moderate positive but non-significant relationship between precipitation and yield (r = 0.518, p = 0.292), and multiple linear regression explained 97.9% of yield variation (R² = 0.979). Precipitation had a stronger explanatory effect than temperature, suggesting that water availability is a more critical factor for forage productivity. These findings provide scientific evidence of regional climate sensitivity and support future data-driven cultivation planning.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. MATERIALS AND METHODS
    1. Study area and period
    2. Climate data collection and definition of extremeweather
    3. Classification of suitability zones and spatial analysis
    4. Dry Matter yield data and regional stratification
    5. Statistical analysis of yield–climate relationships
    6. Mapping software
Ⅲ. RESULTS AND DISCUSSION
    1. Trends in climate change and extreme weather events
    2. Spatial and temporal changes in suitability zones
    3. Regional yield variation
    4. Correlation between climate variables and yield
Ⅳ. CONCLUSIONS
Ⅴ. ACKNOWLEDGEMENTS
Ⅵ. REFERENCES

• Seung Hak Yang(National Institute of Animal Science, RDA, Cheonan 31000, Korea) Corresponding author
• Jeong Sung Jung(National Institute of Animal Science, RDA, Cheonan 31000, Korea)
• Ki Choon Choi(National Institute of Animal Science, RDA, Cheonan 31000, Korea)