1990 Volume 59 Issue 3 Pages 413-418
The experiment was carried out to clarify the influence of irrigation management at the middle growing stage on the rice plant growth and yield in a well drained toamy paddy field. Three experimental plots were prepared with optimum fertilizer applications. Plot 1; three-time drainage treatments were carried out during the period from the later tillering stage to the early meiosis stage. Plot 2; two-time drainage treatments were done during the period from the neck node differential stage to the early meiosis stage. Plot 3; one-time drainage treatment was done for the early meiosis stage. As the results, the soil redox potential in plot 1 was kept at a high level of 300 mV, and the water permeability also increased to two fold volume, 48-60 mm/day, compared with the base of plot 3. The viabilities of rachis branches and healthy state of roots in plot 1 clearly increased or advanced to a desirable extent. As to the influence on the rice yield and qualities, high field of hullled rice was always obtained in plot 1.0. Ocurrence rates of rice kernels in the stand period were slightly depressed by the sufficient drainage in plot 1.
