Abstract
Recently it has been found that in cultivation of rice plants, the vertical water percolation in the paddy soils is an important factor to obtain higher yields. But the effects of water percolation on the growth and the morphogenetical appearances the rice plants manifest, especially roots, under these conditions have not been ascertained. The experiment was carried out to find the effect of the vertical percolation of water on the root hair formation and their growth. The following results were obtained in this experiment. When the water percolated vertically, in the paddy soils at about the speed of 3cm a day, the root hair formation and their growth was accelerated, especially on the part near the root tip. On the contrary when the water did not percolate in the soils, the number of root hairs formed was less and they showed poor growth resembling papilla and furthermore there was no root hair formation near the root tip. It was assumed that the surface area of the roots was increased by water percolation. This experiment also confirms the result of previous experiment (KAWATA and ISHIHARA, 1959) that the root hairs were principally formed in the short cells of the epidermis with polarity under both the percolated and non-percolated soil condition. The oxidation-reduction potential of the water percolated and non-percolated soils was not significantly different. So some other factors related to the oxidation-reduction potential may be responsible for retarding the root formation and their growth. And such factors may be eliminated from paddy soils by water percolation.
