氮肥追施方法和追用时期对超级早稻株型及物质生产的影响

以陆两优996和淦鑫203为材料，研究了相同施氮量条件下不同氮肥追施方法和追用时期对双季超级早稻的株型特征及物质生产特性的影响。结果表明：与移栽后5 d一次性追施氮肥相比，分次追施氮肥有利于提高植株上部三节间的长度，促进壮秆形成和塑造理想株型，延缓叶片叶绿素含量的下降并促进后期光合物质生产量的提高，提高产量。在移栽后5 d施用20%分蘖氮肥的基础上，在倒二叶期追施30%的穗肥有利于形成良好的茎叶配置，提高后期光合物质生产量，从而获得较高产量；穗肥追施过早易使上部三片叶过长、叶片开张角过大，每穗粒数和粒叶比下降，后期物质生产量降低，产量降低；穗肥追施过晚不利于前期获得适宜的叶面积指数(LAI)和较高的物质生产量。

Effects of Nitrogen Topdressing Method and Time on Plant Type and Dry Mass Production of Super Early-rice

Two super hybrid early-rice combinations Luliangyou 996 and Ganxin 203 were used to study the effects of nitrogen topdressing method and time on plant type and dry mass production. The results showed that, compared with the treatment of nitrogen top dressed one time at the 5th day after transplanting one time, higher grain yields were obtained in the treatments of fractionalized top-dressing due to the longer top three internodes, stronger stem and ideotype plant, high chlorophyll contents in leaves and dry matter accumulation from heading to maturity. Under the condition of 20% nitrogen top-dressed at the 5th day after transplanting, 30% panicle nitrogen fertilizer applied in the second leaf age from top was beneficial to obtaining a higher grain yield resulting from the reasonable stems-leaves distribution of the plant and the high amount of dry matter production after heading. If the panicle nitrogen fertilizer applied earlier than that time, the grain yield would be reduced because of the too long leaves, too large leaf drop angle, less spikelet number per panicle, low grain-leaf ratio and low dry matter production after heading. Grain yield would be also reduced if the panicle nitrogen fertilizer applied too late because of the low leaf area index and low dry matter production before heading.