抄録
Plants of Sekitorisai-No. 1 (brittle culm variety) and Haganamugi (stiff culm variety) were subjected to shading treatment at four different stages, ie. culm elongation stage, heading stage, milk stage, and paste stage. Effects of shading on culm growth was examined from the stand point of chemical composition of culm. Generally, it was observed that soluble nitrogen content was increased whereas content of cellulose and silica was decreased by shading. These changes can account for the lowering of culm strength caused by shading. Potassium was related slightly to the osmotic value of tissue juice, but it was not recognized to be directly related to the culm strength. The ratio of potassium to silica seems to express a physiological property of culm; the higher the ratio, the lower was the bending moment of culm.
