[Effects of applying nitrogen fertilizer at different stages in ploughed furrow on dry matter production and yield of rice].

The effects of applying nitrogen fertilizer in ploughed furrow at different stages on dry matter production and yield of rice were studied in a field experiment in 1999. The results showed that applying N fertilizer at booting stage (BS) had better effects on dry weight (2.9 g.hill-1) of leaf, stem and whole plant than at panicle primordia formation stage (PPFS), tillering stage (TS) and regular N fertilization (RF). Meanwhile, the dry weight of leaf and sheath as well as the leaf area index (LAI, 8.9) could be maintained at a high level for a relative long time in BS treatment, compared with PPFS, TS and RF treatments. Similar phenomenon was observed in the growth velocity (0.73 g.d-1.hill-1) of stem and whole plant, and the dry weight (10434 kg.hm-2) of seed. The grain yield of rice followed the sequence of BS > or = PPFS > TS > or = RF. Thus, the optimum stage of applying N fertilizer in ploughed furrow was the booting stage.