To investigate the suitable growing area for Italian ryegrass (cv. Kowinearly and cv. Green-Call), we survey the different effects of climatic conditions on plant growth in the east (hereafter termed Yeongdong) and west (hereafter termed Yeongseo) of the passes in Gangwon Province. The Italian ryegrass was grown in Gangneung of Yeongdong and Wonju and Chuncheon of Yeongseo. The plants showed growth differences depending on the cultivated regions between before and after wintering. The Italian ryegrass for pre-wintering showed the relatively long length of plant height in Wonju. While, we observed the relatively tall plants for growing- and harvestingperiod after wintering in Gangneung. The increased plant height in Gangneung was closely related to all climatic conditions for the growing period and mean- and lowest-temperature for the harvesting period, respectively. The amount of dry matter was 7,490 kg/ha for Kowinearly and 6,490 kg/ha for Green-Call in Gangneung, which has a higher yield than Chuncheon and Wonju. The relative yield index of dry matter was 77% (Kowinearly) and 78% (Green-Call) in Chuncheon and 84% (Kowinearly) and 71% (Green-Call) in Wonju compared to Gangneung as the standard region. Thus, we suggest that Chuncheon and Wonju are the possible areas for cultivation of Italian ryegrass, considering that Gangneung was the optimum growing area in Gangwon Province.

The field experiment was carried out to evaluate changes of dry matter productivity and feed value of Italian ryegrass and triticale at different growth stages in Wonju from 2018 to 2019. Italian ryegrass and triticale forages were harvested at an interval of seven days from May to June. The dry matter yield of Italian ryegrass with 7,870 kg/ha harvested on May 16 was significantly higher than that harvested on May 3 and May 9. The dry matter yield of triticale with 12,050 kg/ha harvested on June 7 was significantly higher than that harvested from May 3 to May 16. The crude protein yields harvested on May 16 were 890 kg/ha for Italian ryegrass and 1,103 kg/ha for triticale and were significantly higher than those harvested on May 3 and May 9. The total digestible nutrient yield(TDN) of Italian ryegrass with 5,223 kg/ha harvested on May 16 was significantly higher than that harvested on May 3 and May 9. The total digestible nutrient yield of triticale with 8,277 kg/ha harvested on June 7 was significantly higher than that harvested during May, but not different from that harvested after June 7. Considering the dry matter yield, crude protein yield and total digestible nutrient yield, it is suggested that the optimal harvesting times for Italian ryegrass and triticale seem to be May 16 and June 7, respectively.