On the Mechanism of decrease of rice yield in ill-drained paddy field

Abstract

Several experiments were carried out to investigate the mechanism of decrease of rice yield in ill-drained paddy field. The results were summarized as follows : 1. No difference of rate of growth of the plant in cooler seasons were recognized between on well-drained and on ill-drained paddy fields, but as it became warmer, the plant grown in the former showed more rapid growth than that in the latter, and at the harvest time the culm length, number of panicles and kernel yield in well-drained paddy fields were greater than that in the ill-drained. 2. The higher the soil temperature in summer, the heavier became the decay of r0ot caused by bad aeration in ill-drained paddy fields as compared with that in well-drained fields. 3. The remarkable outbreak of sesame spot disease and stem rot in ill-drained paddy fields might be attributable to the retardation of absorption of nutritive elements, especially of potassium and silica, caused by injuries in roots.