Effects of Different Rhizosphere Sizes on the Growth, Distribution Patterns and Utilization of Nitrogen Fertilizer in Rice Plant (Oryza Sativa L.)

[摘要] This study was carried out to clarify the effect of controlled rhizophere sizes on various characteristics of each organ at the heading and maturing stage in paddy rice plants (Oryza sativa L., cv. Nipponbare). Investigations were also made on nitrogen accumulation and translocation of 15N top-dressing into each organ with three different types of nitrogen supply, namely, basal-dressing, top-dressing 1 (at the panicle formation stage) and 2 (at the reduction division stage). The dry weight and nitrogen cencentration of each organ increased with increasing rhizosphere size at all growth stages. Recovery of 15N content from top-dressing plots was higher than that from basal-dressing. In top-dressing plots, the latter showed higher 15N recovery rate. Further, in basal and top-dressing at the panicle formation stage, the ratio of 15N recovery increased with increasing rhizosphere size, but rice plants which received top-dressing at the reduction division stage showed no effect of rhizosphere sizes. The ratio of nitrogen distribution at the heading stage in the leaf blade of the plants in the basal-dressing plot increased with increasing rhizosphere sizes. Whereas it was low in the case of nitrogen top-dressed at the reduction division stage. On the other hand an adverse effect was observed in the culm. Further, the ratio of nitrogen distribution in the root of basal-dressing plot was higher than that of top-dressing and it increased with decreasing rhizosphere sizes. At the maturing stage, nitrogen was translocated into the ear from other organs, and the ratio of nitrogen distribution in the ears of the basal-dressing plots was higher than in the top-dressing plots.

[学科分类] 农业科学（综合）

[关键词] ^<15>N;根圏域の大きさ;Oryza sativa L.;重窒素(15N);Recovery of Nitrogen;水稲(Oryza sativa L.);Rhizosphere Size;窒素利用率