on the top of the stem. Each fraction has a distinct surface structure (Hoshikawa, 1989) and chemical composition (Jin and Chen, 2006). To evaluate the effect of morphological part, whole rice straw was manually divided up into four parts; leaf blade, leaf sheath, stem, and panicle. Whole rice straw and these three morphological parts except for the panicle were grained in a Wiley mill (WT-150; Miki seisakusho, Japan) until they passed through 1-mm screen to make whole powder, leaf blade powder, leaf sheath powder and stem powder. These raw materials were stored in an air-dried state.