Due to the recent impact of global warming, heavy rainfall and droughts have been occurring regardless of the season, affecting the growth of Italian ryegrass (IRG), a winter forage crop. Particularly, delayed sowing due to frequent heavy rainfall or autumn droughts leads to poor growth and reduced winter survival rates. Therefore, techniques to improve yield through additional sowing in spring have been implemented. In this study, the growth of IRG sown in Spring and Autumn was compared and analyzed using vegetation indices during the months of April and May. Spectral data was collected using an Unmanned Aerial Vehicle (UAV) equipped with a hyperspectral sensor, and the following vegetation indices were utilized: Normalized Difference Vegetation Index; NDVI, Normalized Difference Red Edge Index; NDRE (I), Chlorophyll Index, Red Green Ratio Index; RGRI, Enhanced Vegetation Index; EVI and Carotenoid Reflectance Index 1; CRI1. Indices related to chlorophyll concentration exhibited similar trends. RGRI of IRG sown in autumn increased during the experimental period, while IRG sown in spring showed a decreasing trend. The results of RGRI in IRG indicated differences in optical characteristics by sowing seasons compared to the other vegetation indices. Our findings showed that the timing of sowing influences the optical growth characteristics of crops by the results of various vegetation indices presented in this study. Further research, including the development of optimal vegetation indices related to IRG growth, is necessary in the future.

This study was conducted to develop a technique for the stable production of Italian ryegrass(IRG) seeds in reclamation sites. Harvesting 35 days after heading in Autumn resulted in the highest production, an average of 2,232kg/ha. The production yield decreased due to seed loss as harvesting was delayed to 45 and 55 days post-heading. For the harvested 35 days post-heading, under growing rice sowing resulted in 80% seed yield of after rice sowing's; spring sowing resulted in 40%. After rice sowing using the domestic IRG seeds of 30kg/ha produced the highest seed yield of 2,507kg/ha. The highest straw yield has resulted when using the imported IRG seeds of 20kg/ha for after rice sowing 35 days post-heading fresh weight 36,667kg/ha, dry weight 14,500kg/ha, and TDN weight 7,895kg/ha.

The objective of this study was to determine the effect of harvesting time of rice on growth characteristics and dry matter yields of Italian ryegrass (Lolium multiflorum Lam., IRG) ‘Kowinearly’ after seeding them in paddy field. Experiments were performed in National Institute of Animal Science, RDA (Cheonan, Choongcheongnam-do province of Korea) for four years (2011~2014). Italian ryegrass variety ‘Kowinearly’ was seeded at experimental paddy fields before rice harvest in late September. Rice were harvested at 10, 20, and 30 days after seeding of IRG. As the harvest time of rice became later, the number of tillering before winter was reduced and IRG plant length before winter was shorter. The dry matter yield of IRG was also reduced. When rice were harvested at 20 days and 30 days after sowing of IRG compared to the rice harvested in autumn at 10 days after sowing of IRG, the number of tillering for IRG before winter was decreased by an average of 19% and 40%, respectively. The winter survival ratio of IRG was decreased by an average of 13% and 19%, respectively. Their dry matter yields were also reduced by an average of 8% and 19%, respectively. The heading date was different from each other in three years. The plant length at the time of IRG harvest in the spring was not significantly different among treatment groups. Taken together, our results suggest that when Italian ryegrass is grown in paddy fields by the method of ‘seeding of IRG before rice harvest’, rice should be harvested as soon as possible after sowing of IRG ‘Kowinearly’ in the autumn to increase forage productivity.