Comparison of Dry Matter Yield and Nutritive Components in Two Cultivars of Forage Rice with Different Heading Dates

Abstract

To extend the harvest period of forage rice with short panicles, we compared the dry matter yield and nutritive components of two cultivars with different heading dates from late August through October. In addition, we investigated whether nitrogen top-dressing at the booting stage effectively increases crude protein content. There was no significant difference in dry matter yield between “Chugoku Shi-224” (an early-heading strain) and “Tsukisuzuka” (a late-heading cultivar) until September, whereas the yield of “Tsukisuzuka” was higher than that of “Chugoku Shi-224” in October. The sugar content in leaves and stems, which plays an important role in the fermentation of silage, was lower in “Tsukisuzuka” than in “Chugoku Shi-224” until early September but was similar in the two cultivars in October. Total digestible nutrients tended to be higher in “Chugoku Shi-224” until September but higher in “Tsukisuzuka” in October. There was no significant difference in crude protein content between the two cultivars, and nitrogen top-dressing increased the content in both cultivars without affecting dry matter yield. These results indicate that the cultivation of “Chugoku Shi-224” in addition to “Tsukisuzuka” enables the harvest of forage with high nutritive value in late August and September, when the nutritive components are not fully accumulated in “Tsukisuzuka”. Furthermore, nitrogen top-dressing at the booting stage appears to improve the nutritive value of forage rice by effectively increasing crude protein content.