抄録
The nitrate nitrogen content of brown rice was investigated on the nonglutinous and glutinous types by lowland and upland polyethylene film mulching cultures of lowland rice at the Alpine Region Branch and the North Branch of the Iwate Agricultural Experiment Station and by upland and upland polyethylene film mulching cultures of lowland and lowland-upland hybrid rices at the Main Station. The nitrate nitrogen content of the brown rice contained approximately 0.4 to 0.5mg% on dry basis. However, the upland mulching culture gave higher nitrate nitrogen content in lowland brown rice as compared with the lowland culture. The average increasing index, i.e. (upland mulching culture/lowland culture)×100, of non-glutinous type, glutinous type and both types was 113.9, 108.0 and 112.3, respectively. The upland mulching culture also gave higher nitrate nitrogen content in lowland and lowland-upland hybrid brown rices as compared with the upland culture on the same manuring condition. The average increasing index, i.e. (upland mulching culture/upland culture)×100, is as follows : a) lowland brown rice: non-glutinous type 108.3, glutinous type 111.1 and both types 109.2. b) lowland-upland hybrid brown rice: non-glutinous type 112.8, glutinous type 106.0 and both types 109.0.
