Abstract
In the paddy field it is common to irrigate flooding water during the most part of growing seasons. There have been many observations concerning the meaning of flooding, but tbe experiments on the effect of flooding upon rice plant itself have not always been done enough. The author has planned these experiments intending to make this point clear up; this paper reports only preliminarily the tendency of gowth under flooding water. The rice plants were grown in Wagner's pots; flooding plots being 7cm flooded continuously, and the contrast being kept moist enough with no flooding. 1) In Kanto District, the temperature of early growing season of rice is rather low, hencc the continuous flooding promotes the growth according to its superiority in temperature. But later in summer, the soil aeration seems to become a important factor, and flooding is rather disadvantageous for growing of rice. 2) Flooding affects the structure of the lower portions of stem and may weaken them mechanically; weakness may be chiefly due to thin wall of culm and want of mechanical struetures.
