The objective of this study was to evaluate the dry matter ratio and other agronomic characteristics in our Italian ryegrass (Lolium multiflorum Lam.) strain "TK2H-3rd," which was selected from the "TK2" tetraploid strain with a high dry matter ratio through 3 generations. We sowed "TK2H-3rd" and "TK2" for 3 years and investigated snow endurance, heading date, lodging tendency, plant length, dry matter ratio and weight, and amount of non-fiber carbohydrate (NFC). We confirmed that "TK2H-3rd" had a higher dry matter ratio and NFC than those of "TK2". "TK2H-4th," which was selected from "TK2H-3rd" for 1 more generation with a high dry matter ratio, was tested for responses to a low sowing rate. TK2H-4th had a higher dry matter ratio and NFC than those of "TK2", especially in low sowing plots. Therefore, we concluded that the higher dry matter ratio of "TK2H-3rd" and "TK2H-4th" was partially attributable to a higher accumulation of NFC than that by "TK2".