The Effect of the Deep Placement of Top-dressing Fertilizer and Intermittent Irrigation on Physiological and Ecological Characters in Rice Plant

摘要

This experiment was conducted to investigate the influences of the deeply placed top-dressing fertilizer and of intermittent irrigation on physiological and ecological characters in rice plant and on rice yield. The treatments consisted of control (plot I), top dressing at deep layer (plot II), and intermittent irrigation plus treatment of plot II (plot III). The results obtained are as follows: 1. The rice yield recorded was 120 percent in plot II and 124 percent in plot m as compared to the control plot. 2. In plot n the plant height was taller then those of control but lodging resistance was greater. This was mainly due to the retarded elongation of lower internode and increased breaking strength of stem. 3. As compared to the plot I, the degree of chlorophyll destruction of leaves was lower in plot II and plot III. The flag leaves in plot III were erect. 4. The α-naphthylamine oxidizing activity of root was most active in plot III, with plot II coming to the next. It is possible, however, that the root activity is closely related with the senescence and inclination of the leaf. 5. The effect of fertilizer applied as a deeply placed top-dressing was different even within one and the same hill. Great differences were shown according to the place of fertilization in the percentage nitrogen content of leaf-blade and in the root activity to oxidize α-naphtylamine. In other words, the nutrients were absorbed by the roots which distributed in deep layer and transferred to the tillers connected with them. 6. The percentage of potash and silicate contents in plant at the heading and harvesting stage were highest in plot III.