The Role of Root in Nitrogen Metabolism of Crop Plants

[摘要] In many papers hitherto reported, it was concluded logically that the roots synthesize and supply the shoot with certain substances necessary for continued metabolism of protein. The authers' experiments showed that the roots played an important role in RNA and nitrogen metabolism of the shoot. The object of these experiments was to clarify the relation between protein and RNA metabolism in the plant and the influence of the roots on the RNA synthesis in the shoot. Results obtained are as follows 1) When rice plants were grown under various conditions such as different light intensity and nutrient supply, it was seen that the changes of protein content were accompanied by the changes of RNA level, i.e. strong light or excessive nutrients resulted in the increase of the RNA and the protein level. Accordingly, it was confirmed that there was high correlation beween protein and RNA contents. From this fact it seems logical to assume that protein metabolism is controlled by RNA in both the organs, shoot and roots. 2) When the roots were removed from the shoot, the RNA content of shoot went down to 65 % in comparison with the control. If, however the shoot formed roots, the RNA contents tended to increase, and the protein content showed the same tendency as that of RNA. 3) As regards the relationship between roots and shoot, it was observed that elongation of the newly developing leaf was largely retarded by the removal of the roots, (rice plant). 4) The changes of RNA, acid soluble-P and nitrogen compounds which occur in the rooting process of cuttings were investigated on Commelina communis. Before rooting, the RNA content decreased and simultaneously .the acid soluble-P content increased. After rooting, however, the RNA regained the original value and the acid soluble-P decreased. Here again, the protein content behaved in the same way as RNA. 5) If the leaf is provided with a growing root system, the incorporation of 32P into RNA in the case of foliar application of 32P proceeds more rapidly as compared with the leaf with no roots (tobacco, soybean and rice plant).

[学科分类] 农业科学（综合）