Effect of Coated Urea Topdressing on Growth and Yield of Rice Plant

[摘要] The effect of coated urea topdressing at the neck node initiation stage on rice growth and yield was evaluated in the field experiments in l985, l986 and l987. The following results were obtained: 1) Nitrogen from topdressed fertilizer (LP70) was progressively absorbed by the plants up to maturity. The percentage recoveries by plants were 65∼70% (equivalent to around 80% of released N from fertilizer). On the other hand, the duration of nitrogen absorption from ammonium sulfate (AS) topdressed at the panicle initiation stage was less than 14 days and percentage recoveries by plants werc 40-60%. As a result of N absorption pattern, the yield and sink size obtained in LP70 plots were higher. 2) There was no difference in the length of uppermost 4 leaf blades and clum between LP70 plots and AS plots in spite of the big difference in N absorption pattern.

[学科分类] 农业科学（综合）

[关键词] N absorption pattern;緩効性肥料;Recovery of applied N;N吸収パターン;Slow release fertilizer;N利用率