水稲の地上部の形質におよぼす根の役割に関する研究 : 第4報 窒素の欠除および株内根域環境のちがいが根と地上部におよぼす影響

抄録

This study consists of two categories. In order to clarify the effect of elimination of nitrogen application at different growth stages on the degree of leaf senescence and the root activity, the first experiment was carried out under water culture conditions. The second one was aimed to investigate variation of characters and movement of mineral nutrients within one and the same hill after root systems of the plant were separated and exposed to two different environments. The results obtained were as follows. (1) The elimination of nitrogen application greatly affected the chlorophyll destruction of the excised leaf and reduced the root activity. (2) The elimination of nitrogen application resulted in a great retardation of the root activity both at the tillering stage and the stage of reduction division. The activity of the lower nodal roots were severely affected at the tillering stage while that of the upper nodal roots was mostly retarded after reduction division stage. (3) By dividing roots into two halves and exposing each one to different nitrogen leveles, it was found that tillers and their roots were closely related each other. It appeared that the roots distributed in a given root environment affected mainly the tillers connected with them. The movement of mineral nutrients among the tillers which connected different root systems within one and the same hill had being independent each others. (4) When different root environments were given to the plant, certain elements such as calcium, iron and manganese seeiried to be difficult to move from one tiller to another, while nitrogen, potassium, phosphorus and magnesium moved relatively easily each other.