关键词: 春优84, 播种期, 秧龄, 干物质累积, 产量

Abstract: Field experiment was conducted using Chunyou 84 (Oryza sativa，japonica) with five sowing dates (May 10th，20th，30th and June 9th，19th)， five seedling age(20，25，30，35 d and 40 d) and nitrogen fertilizer levels (1500， 1875， 2250， 2625 and 3000 kg N·hm-2) to study the effects of different sowing dates， seedling age and nitrogen rates on cumulative rates of dry matter，main agronomic characters and yields. The objective of the experiment is to clarify the related highyield cultivation techniques of hybrid japonica rice Chunyou 84 in Jinhua and provide technical support and theoretical basis for highyield cultivation. The results showed that along with the delaying of sowing dates， the growth process of Chunyou 84 was correspondingly delayed， growth stages were significantly shortened. The yield of Chunyou 84 was the highest when the sowing date was on May 10th， the decreasing range of yield increased with the delaying of sowing date. The yield of Chunyou 84 was the highest when the seedling age was 20 d， the yield remarkably declined after the seedling age of 25 d. When the seedling age increased， the spikelets number per panicle and the number of effective panicles of Chunyou 84 decreased. The dry matter distribution in panicles significantly declined as the increasing of nitrogen application at the maturity stage. The results indicated that the N4 treatment got less dry matter distribution in panicles and yield than the N3 treatment， which indicated that excessive nitrogen application was not helpful for raising the grain field.The reasonable sowing date for Chunyou 84 as single cropping late rice was May 10th-20th，proper early sowing date was helpful for raising the yield. The optimal seedling age that Chunyou 84 can get higher yield was in the range of 20-25 d， the yield significantly decreased after the seedling age of 25 d. The optimal N application for Chunyou 84 was 2625 kg N·hm-2， the excessive N application decreased the yield．

Key words: Chunyou 84, sowing date, seedling age, dry matter accumulation, yield