Studies of Protein Content in Rice Grain : VI. Effects of the foliar application of urea on the translocation of nitrogen to the ear and the protein content of brown rice

Abstract

The topdressing of ammonium sulfate and the foliar application of urea were carried out at the full heading time of rice plants on the paddy field where the nitrogen of 4 levels, that is 0, 5, 10 and 15 kg/10a, applies as the basal dressing, and the changes of nitrogen content of each organ of rice plants, the accumulations of nitrogen in the ear and the differences of protein content of brown rice were investigated. 1. The nitrogen percentages of leaf blade, leaf sheath and culm were high in order of the topdressing, the foliar application and the non-topdressing. The nitrogen percentages of ear were high in order of the foliar application, the topdressing and the non-topdressing. These orders were not changed regardless of the difference of varieties and the difference of the nitrogen amounts of basal dressing. 2. The nitrogen amounts accumulated in the ear were high in order of the foliar application, the topdressing and the non-topdressing. The more the nitrogen amounts of basal dressing, the more the nitrogen amounts accumulated in the ear. 3. The accumulation rate of nitrogen in the ear was higher on the foliar application plots compared with the other plots. It was assumed that the nitrogen absorbed by foliar application accumulated in the ear more immediately than the nitrogen absorbed from the root. 4. The protein percentage of brown rice was highest on the foliar application plots. The protein percentage of brown rice on the foliar application plots increased 9∼13% than that of the topdressing plots and 31∼34% than that of the non-topdressing plots on the average of every basal dressing plot. 5. The protein percentage of brown rice significantly increased by the foliar application of urea regardless of the cool-summer damage due to delayed growth.