【作者】 王惠芝；

【导师】 丁艳锋； 王绍华；

【作者基本信息】 南京农业大学 ， 作物栽培学与耕作学， 2007， 硕士

【摘要】 拔节长穗期是争取大穗的关键时期，每穗粒数是产量的主要构成因素之一，尤其是争取高产更高产，其作用更为突出。本研究选用武育粳3号(常规粳稻)和86优8号(杂交粳稻)两个穗粒数不同的粳稻品种，采用不同的氮素穗肥处理，对不同施氮水平以及不同穗肥施用时期处理下，穗分化各时期水稻的生长发育状况进行研究，从水稻幼穗的生长动态、茎秆发育、植株各器官的碳氮代谢水平等方面对穗粒数形成的影响进行了探讨，主要研究结论如下：(1)整个穗分化期水稻幼穗鲜重大致呈“S”型曲线变化，前期生长较慢，进入颖花分化后期幼穗鲜重急剧增加。86优8号从抽穗前20d开始，武育粳3号从抽穗前16d开始，出现幼穗生长的氮肥效应转换期。穗分化前期穗／茎比较小，后期穗／茎比逐渐增大。抽穗前4～16天的穗重增长速率高于茎重增长率，穗对营养物质的竞争能力超过茎秆。抽穗期的穗重及茎秆重量与每穗颖花数关系密切，均表现为随重量增加而增加。(2)水稻于倒3.5叶期施用穗肥以后，水稻各器官氮含量表现为先升高后降低，而碳(NSC)含量先降低后升高，各处理变化趋势基本一致。不同处理间比较，施肥越多，氮含量越高，而碳含量在穗分化前期随施肥量的增加而降低，抽穗前12d以后，碳含量随施肥量的增加而升高。碳氮比变化与碳含量关系密切，不同处理表现为穗肥施量越多，碳氮比上升越缓慢。单株的碳、氮含量及碳氮比在抽穗前24d与颖花数为二次曲线关系，抽穗期碳含量及碳氮比与颖花数为直线相关，施肥量适宜，单株碳氮比在抽穗前16～12d超过对照，颖花现存数较多。叶片的碳、氮含量在抽穗前24d、抽穗前12d与颖花数呈抛物线关系；抽穗前24d叶鞘中的碳、氮含量及碳氮比和颖花数的关系与单株表现一致；抽穗期叶鞘中NSC含量越多，每穗颖花数也越多。(3)穗分化前期，单株水稻氮积累较高，后期较低，但NSC积累与氮的积累相反。枝梗及颖花分化期，氮在植物体内的积累以叶片较多；进入减数分裂期以后，碳在植物体内的积累以叶鞘较多。每穗颖花现存数与抽穗前20～12d叶片碳的日积累量成正相关(86优8号R=0.901书；武育粳3号R=0.944*)，与该时期中心库内碳的累积量也存在一定的相关性。本试验条件下，整个穗分化期86优8号和武育粳3号单株水稻碳积累量分别为2156.64、1668.21mg／株，氮积累量分别为60.49、58.02mg／株，水稻植株处于一个适宜的碳氮平衡状态，对增加现存颖花数有良好的效果。(4)穗肥施用时期不同，植株体内碳氮代谢情况有一定差异。倒3.5叶期施肥，可以促进枝梗及颖花分化期植株体内氮的代谢，有利于增加颖花分化数，施肥越多，抽穗前32～20d植株碳的积累越少；倒1.5叶期施肥，可以促进减数分裂期植株体内碳代谢，有利于减少颖花退化，施肥越多，植株体内碳含量越多。更多还原

【Abstract】 Increasing spikelet number per panicle is one of the key factors for high yield, and panicle differentiation is the important stage for spikelet number formation. In this study, different nitrogen （N） pot experiment involving two japonica rice varieties Wuyujing3 （general rice） and 86you8 （hybrid rice） ,and different treatments were conducted. Researched young panicle growth, stem development, carbon-nitrogen metabolism of different organs in rice and illustrated that effect nitrogen fertilizer applied on spikelets number formation. Results showed as following:1. The change tendency of panicle fresh weight is "S" during the whole younger panicle initiation stage. The panicles grow slowly prophase, but grow fast markedly from spike differentiation. 86you8 and Wuyujing3 appear nitrogen fertilizer effect conversion stage of younger panicle respectively 20 days and 16 days before heading.The weigh ratio of panicle to stem at the early stage was lower and then increase gradually during younger panicle initiation stage. The weight ratio of diurnal increases of panicle to stem from 4 to 16 days before heading was correlated to the spikelet number per panicle significantly, panicle got more nutrient than internodes during this stage. The fresh weight of panicle and stem at the heading stage was correlated positively to spikelet number per panicle; and the more rapidly the panicle weight increased under enough N, the more spikelet number increased at this stage.2. The plant obtain nitrogen compound and consume non-structure carbohydrate（NSC） after applied N fertilizer from the start of panicle initiation, the N content is increased firstly and then decreased, NSC content is lower firstly and then higher in rice source and sink organs. The change tendency of different treatments was the same. Compare with different treatments, the more N applied, the more N content of organs, but NSC content was lower prophase and then increased 12 days before heading. The C/N ascend slowly with the nitrogen fertilizer level in creasing in different treatments.The N and NSC content and theirs ratio of plant 24 days before heading was two curve relation to spikelet number per panicle; and that heading stage was correlated positively to spikelet number per panicle; when N fertilizer applied feasible, the C/N of plant exceed check during 12-16 days before heading have more survived spikelets number per panicle. The NSC and N content at 24 days and 12 days before heading was parabola to spikelets number per panicle; it is the same as the plant that NSC and N content and theirs ratio before heading 24 days in sheath. The more NSC in sheath, the more spikelet number at heading stage3. The N accumulation decreased gradually during panicle initiation period, but the NSC accumulation was in opposition to N accumulation. The N accumulation of plant was highest in leaf at branch and spike differentiation stage, and NSC accumulation was highest in central sink during meiosis period. The NSC accumulation of diurnal increases of leaf from 20 to 12 days before heading was correlated to the spikelet number per panicle significantly（86you8 R=0.901*;wuyujing3R =0.927*）, NSC accumulation of in central sink in this stage was also correlated to the spikelet number per panicle. The carbon-nitrogen metabolism of plant kept feasible balance state when 86you8 and wuyujing3 NSC accumulation of plant was respectively 2156.64、1668.2lmg/plant and nitrogen accumulation respectively 60.49、58.02mg/plant under nitrogen fertilizer amount respectively 120、180kg/hm^-2 in this experiment, which was in favor of increasing survived spikelets.4. The carbon-nitrogen metabolism was different with nitrogen fertilizer application time. The nitrogen metabolize of plant rapidly at branch and spikelet differentiation stage when nitrogen fertilizer applied from the start of panicle initiation, which was in favor of panicle differentiation, the more nitrogen fertilizer applied ,the little NSC of plant accumulated 32-20days before heading. The carbon metabolize of plant rapidly from meiosis on when nitrogen fertilizer applied at leaf remainder 1.5 stage, which was in favor of decreasing retrograded spikelet number, the more nitrogen fertilizer applied, the more NSC content of plant had.更多还原