Abstract: In order to study the effects of controlled-release nitrogen fertilizer application ratio on the yield of direct-seeding japonica rice under different panicle formation types, Nanjing 9108 was as material, and the different proportion between controlled-release nitrogen fertilizer formula (40 d release period controlled-release N fertilizer: 100 d release period controlled-release N fertilizer=1∶4) and urea were set in the rice-wheat double cropping area of Jiangsu province using split-plot design. Three different basic seeding treatments were as main plots, which investigated the proportion between the main stem and effective panicles at maturity stage to represent three rice populations (stem type, stem and tillers type, and tillers type). The different ratios of controlled-release nitrogen fertilizer formula and urea (pure nitrogen ratio of 5∶5, 6∶4 and 7∶3) were subplot. The result showed that it was different between the suitable formula of controlled-release nitrogen fertilizer and the proportion of one-time base application of urea in direct seeding of Japonica rice under different panicle forming types to get high yield. In the stem type, the effect of base application ratio of controlled-release N fertilizer and urea at 7∶3 was the best, and the grain yield reached 10.0 t·hm^-2; in the stem and tillers type and the tillers type, the ratio of controlled-release N fertilizer and urea at 5∶5 had the best effects, and the grain yield were 9.5 and 9.4 t·hm^-2, respectively. Among the panicle formation types, the yield of treatment 7∶3 in the stem type was the highest, which had significant advantages in terms of population spikelet number, photosynthetic potential and dry matter accumulation at the later growth stage. In conclusion, under different panicle formation types of direct seeding rice, controlled-release N fertilizer with appropriate proportion of base application could increase yield. The appropriate increase of basic seedling should improve the proportion of main stem and effective panicle. The controlled-release nitrogen fertilizer formula with its preponderant ratio of 7∶3 combining with one-time basal nitrogen fertilizer technology would be helpful to reach high yield of direct seeding conventional japonica rice.

Key words: japonica rice, controlled release urea, one-off base fertilization, direct seeding rice, panicle formation type, yield

摘要： 在江苏省稻麦两熟轮作地区，以南粳9108为材料，在控释氮肥配方（40 d释放期控释氮肥∶100 d释放期控释氮肥=1∶4）和速效氮肥的不同配比下，研究全程氮素一次性基施条件下控释氮肥施用比例对不同成穗方式下直播常规粳稻产量的影响。试验为裂区设计，主区设置3种不同基本苗处理，在成熟期调查其主茎占有效穗数的比例，以分别代表主茎为主成穗型、主茎分蘖并重成穗型和分蘖为主成穗型的3种水稻群体，控释氮肥配方和速效氮肥的不同配比为副区，分别为纯氮比5∶5、6∶4和7∶3。结果表明：不同成穗方式下直播常规粳稻达到高产时的适宜控释氮肥配方与速效氮肥的一次性基施配比存在差异，主茎为主成穗方式下，控释氮肥配方与速效氮肥以7∶3的纯氮比例配施时产量最高，产量为10.0 t·hm^-2，较5∶5和6∶4处理显著提高53%~7.5%；主茎分蘖并重型和分蘖为主成穗型两种成穗方式下，控释氮肥配方与速效氮肥以5∶5的纯氮比例配施时产量最高，分别为9.5、9.4 t·hm^-2，较其他处理显著提高9.2%~10.5%和9.3%~11.9%。在成穗方式间，以主茎为主成穗方式下的7∶3处理的产量最高，该处理在群体颖花量、生育后期光合势及阶段干物质积累等方面都具有显著优势。综上，不同直播稻成穗方式下基施适宜比例的控释氮肥均能获得较高的产量，适当增加基本苗以提高主茎占有效穗比例，以主茎成穗为主，配套控释氮肥配方和速效氮肥配比为7∶3的一次性基施氮肥技术有助于实现直播常规粳稻的高产。

关键词: 粳稻, 控释氮肥, 一次性基施肥, 直播稻, 成穗方式, 产量