This study was conducted from 2022 to 2024 at the Grassland and Forage Crops Division, National Institute of Animal Science (RDA), in Cheonan, Korea, to develop a medium-maturing variety of Italian ryegrass (Lolium multiflorum Lam.). The newly developed tetraploid cultivar, named ‘Spider’, is characterized by its green leaves, semi-erect growth habit in late autumn, and erect growth habit in mid-spring. With a heading date of May 16, ‘Spider’ is classified as a medium-maturing variety. Compared to the control cultivar ‘Kowinmaster’, ‘Spider’ has a 1.0 mm wider leaf blade, a 1.6 cm longer leaf blade, and is 5 cm taller in plant height. Its dry matter yield (10,169 kg/ha) is significantly higher than that of ‘Kowinmaster’ (p<0.05). The crude protein content of ‘Spider’ is 10.4%, which is 0.2% higher than that of the control. Additionally, ‘Spider’ has a neutral detergent fiber (NDF) content of 49.5% and an acid detergent fiber (ADF) content of 26.6%, showing a 2.2% lower NDF and a 0.2% higher ADF compared to ‘Kowinearly’.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. MATERIALS AND METHODS
    1. Crossing combinations
    2. Seed production of synthetic lines
    3. Experimental design
    4. Growth characteristics analysis
    5. Dry matter (DM) and dry matter yield (DMY) analysis
    6. Evaluation of forage quality
    7. Statistical analysis
Ⅲ. RESULTS AND DISCUSSION
    1. Morphological characteristics
    2. Cold tolerance
    3. Dry matter yield
    4. Feed value
Ⅳ. CONCLUSION
Ⅴ. ACKNOWLEDGEMENTS
Ⅵ. REFERENCES

• Ki-Won Lee(Forages Production Systems Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea) Corresponding author
• Sang-Hoon Lee(Forages Production Systems Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)
• Yowook Song(Forages Production Systems Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)
• Bo Ram Choi(Forages Production Systems Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)
• Chang-Woo Min(Forages Production Systems Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)
• Jae Hoon Woo(Forages Production Systems Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Republic of Korea)