Abstract
To make clear the differences in the degree of root-rot infestation and nutrient absorption of rice plant grown on well-drained and ill-drained paddy fields, several experiments were carried out. The results were as follows : (1) Suppression in absorption of nutrients such as nitrogen, phosphate or silica and decrease in number of silicified cells in the leaves in the plants grown on ill-drained paddy fields as compared with those on well-drained fields, may be partially attributed to high degree of root-rot infestation caused by low oxidation-reduction potential of the soil. In fact, the descent of Eh value of the soil in the former case was found throughout the whole growth cycle of plant. (2) High content of reserve starch in the basal portion of the shoot and in the panicles of the plants on well-drained paddy fields might be a result of good assimilation, and translocation of starch to the kernels were also smooth resulting in an increase of the weight of 1000 grains.
