Effects of Cutting Height of the First Crop on Estimated Total Digestible Nutrient Concentration and Yield in Double-Harvested Rice

摘要

We examined the effects of cutting height (15, 5, or 0 cm) and equipment traffic treatment (treatment or no treatment) of the first crop on estimated total digestible nutrient (TDN) concentration and yield in double-harvested forage rice (Oryza sativa L.) in southwestern Japan. In forage rice production, it is important to maximize the nutrition in leaf and stem, especially leaf sheath plus stem (stem) due to the high ratio to the whole plant weight, rather than in panicle, to minimize the overall loss of nutrition from the crop. In the total of the first and second crops, stem estimated TDN yield was lower when the first crop had been cut at a height of 15 cm (517 g m(-2)) than 5 and 0 cm (576 and 598 g m(-2), respectively). In the second crop in 2006, stem estimated TDN concentration decreased from 541 to 478 g kg(-1) with increasing cutting height from 0 to 15 cm, because the organic cellular contents (OCC), which include starch and sugar, concentration decreased. The second crop headed earlier with increasing cutting height. Thus, although starch was translocated from the stem to the panicle in the second crop when the first crop was cut at a height of 15 cm, insufficient starch was translocated to the panicle when the first crop was cut at 5 and 0 cm because of the low temperatures after heading. To reduce the overall loss of nutrition from a crop, it is effective to cut stubble lower. In the second crop, whole plant estimated TDN concentration and yield was not greatly influenced by equipment traffic treatment.