【作者】 晏娟；

【导师】 沈其荣； 尹斌；

【作者基本信息】 南京农业大学 ， 植物营养， 2009， 博士

【摘要】 我国稻田单季氮肥用量平均为180 kg N ha-1，比世界平均用量大约高75%左右。在江苏等一些高产稻区,稻田的施氮量为270-300 kg ha-1,少数田块甚至高达450 kgha-1。氮肥的高投入造成其利用率降低,据报道,我国稻田氮肥利用率一般为30%-40%,在施氮量较高的太湖地区,甚至不到20%。较低的氮肥利用率不仅增加作物种植成本,更带来严重的环境污染。在一定区域内控制氮肥的总用量,确定在一定产量目标下的氮肥区域平均适宜用量,这不仅有利于提高水稻的氮肥利用率,保证区域的水稻总产量,而且可以减轻因氮肥过量施用所引起的环境负荷。本项研究于2003年到2006年在江苏省常熟农业生态实验站及乡镇农田上进行大田和微区试验,2007年在南京农业大学温室内进行盆栽实验。采用田间试验,结合15N示踪技术和水稻土培试验,研究和确定了太湖地区稻麦轮作系统下水稻和小麦的氮肥区域平均适宜用量；同时还研究了氮肥用量、施肥时期对水稻的生长发育、稻谷产量及氮素吸收、转运和利用的影响；采用新的氮高效水稻品种和施用水面分子膜以提高氮肥利用率等方面的研究。主要的研究结果如下：(1)从2003年到2006年在太湖地区不同类型土壤上进行了不同氮水平的田间试验,以研究太湖地区稻麦轮作系统下氮肥区域平均适宜用量。区域平均适宜施氮量是以各田块的适宜施氮量为基础指标,试验分析所得太湖地区水稻的区域平均适宜施氮量为167 kg ha-1,小麦为212 kg ha-1。两者加起来,太湖地区稻麦轮作系统下的区域平均适宜施氮量是379 kg ha-1yr-1,这个数据相对于最大产量下的施氮量减少了21.7%,相对与农民的习惯施氮量减少了36.8%。在区域平均适宜施氮量下,作物产量和农民收益并没有降低,反之,有效提高了氮肥利用率。(2)2005年在常熟市大义镇农田上进行了田间小区及微区试验,研究了不同施氮量对两个品种水稻(新品种4007和当地品主栽品种武运粳15,WJ15)的产量、氮素吸收、累积、转运及利用的影响。结果表明4007的籽粒产量在各个施氮水平下显著高于WJ15。施氮量显著促进了水稻各生育期地上部氮素的累积,水稻从分蘖盛期到拔节期植株氮素累积量最大,占总生育期的37%-39%。当施氮量从0 kg ha-1。增加到250kg ha-1,4007的氮素转运量从72.0 kg ha-1上升到104 kg ha-1,氮素转运率从66%下降到51％；而WJ15的氮素转运量从57.0 kg ha-1上升到96.5 kg ha-1,氮素转运率也从57%下降到47%.籽粒中的氮素65%-88%来自营养器官的转运,只有12%-35%是后期从土壤吸收所得。两个品种水稻均表现为15N在籽粒中的分配比例随施氮量的增加逐渐降低,在茎叶的分配率相应上升,根中15N的分配率没有差异,说明增施氮肥有利于水稻营养器官对肥料的吸收。试验结果还表明,15N在水稻各器官的分配为：籽粒>茎叶>根,4007中15N在籽粒中的分配比例要高于WJ15,在茎叶中低于WJ15。说明氮素再分配效率是决定4007水稻高产和高氮肥利用率的重要因素之一。(3)运用15N示踪技术研究了不同生育时期水稻对肥料氮的吸收和分配。结果表明：15N分别标记基肥(N1)、分蘖肥(N2)和拔节孕穗肥(N3)的处理中,水稻吸收的氮素在分蘖盛期、拔节期和开花期分别有23.1%、8.3%和19.9%来自标记肥料；从开花期到成熟期,不同时期标记的15N转移量大小为：拔节孕穗追肥(N3)>基肥(N1)>分蘖期追肥(N2),但基肥的氮素转运效率最高,其他两次追肥氮素转运效率相当；在成熟期,N1、N2、N3处理残留在的稻草中的15N分配比例为24.3%、26.7%和30.4%.无论是氮肥基施,还是分蘖期或拔节孕穗期追肥,水稻开花期之前所吸收的15N主要分配在叶片中,其次是鞘,再次是茎；开花期后,随着15N从营养器官向籽粒中的转移,叶片、茎干和鞘中的15N分配百分比逐渐下降,籽粒15N的分配百分比逐渐上升。试验结果还显示,基肥15N标记时,分蘖期所吸收氮来自肥料最高,为23.1%,随生育期的推进逐渐下降,到成熟期仅为10.6%,成熟期吸收的氮来自分蘖期和拔节孕穗期追施的氮肥分别为5.9%和12.4%.综上所述,当土壤氮素含量不高时,基肥对水稻整个生育期生长很重要,基肥适量增加可显著增加水稻茎蘖数,对水稻群体质量建成有决定作用；拔节孕穗肥可显著促进水稻生育后期的籽粒灌浆和充实,增加拔节孕穗期的氮素供应有利于提高水稻的氮素收获指数.(4)田间试验条件下,探讨了在施200 kg N ha-1和施250 kg N ha-1两种处理下,加施水面分子膜对太湖地区水稻的增产效应,对稻田氨挥发的影响及不同生育期水稻各器官吸氮量的变化状况；同时应用15N示踪法研究了加膜对水稻氮素吸收及利用率的影响.结果表明,在施200 kg N ha-1的条件下,加膜对水稻的产量效应及氨挥发作用不明显,但在生育前期可显著促进茎叶对氮素的吸收,生育后期使茎叶的氮素大量向籽粒转移,使得籽粒吸氮量提高了13.2%；当施250 kg N ha-1时,加膜可促进分蘖,有利于有效穗数的形成,使水稻增产17.8%,氨挥发总量可减少4.15个百分点,整个生育期除分蘖初期外,水稻茎叶的吸氮量呈递增趋势,但籽粒吸氮量增加不明显。15N示踪法测得结果显示无论那种处理,加膜都有利于水稻各器官对氮素的吸收,植株总体吸氮量可增加3.8%-5.9%；同时,加膜使得表层土壤15N的丰度增加,土壤残留提高,从而减少氮素的损失,对环境做出贡献。更多还原

【Abstract】 The average nitrogen (N) fertilizer in China applied to rice was 180 kg N ha-1, which is 75% higher than the world average. In some regions with high rice productions, such as Jiangsu Province, the common N application rate in rice season was 270-300 kg ha-1, and even 450 kg N ha-1 was applied in some area. N recovery rate from fertilizer (REN) was relatively low when applied in high doses, and thus it is reported that the REN by rice in China was around 30-40%, or even less than 20% could be found in Tai lake regions, where over N fertilization was often observed. Low REN did not increase the cost of the crop production, but resulted in serious environment pollution. Thus, the REN and net incomes of farmers could increase substantially and N loss could decline significantly when optimal N fertilizer application was practiced. Field experiments and micro-experiments were carried out from 2003 to 2006 at Agricultural Ecological Experiment Station and some farmer’s field in Changshu County, Jiangsu Province, and pot experiment was conducted in green house at Nanjing agricultural university in 2007. The objectives of this study are:(1) To determine the Regional Mean Optimal N application Rate (RMOR) for rice and wheat production with a good consideration of increased REN and minimized N loss; (2) To identify the effects of N application rate and timing on rice growth, grain yield, N uptake, translocation and REN; (3) To assess the effects of improved REN by planting new rice cultivar with high REN and applying water surface film-forming material in the field. The results were showed as follo wings:1. In order to study the RMOR to rice and wheat in Taihu Region, field experiments were conducted with different N application rates from 2003 to 2006. RMOR was calculated based on the average of the optimal N rate in each field. They were 167 kg N ha-1 for rice and 212 kg N ha-1 for wheat. The N application rate for the rice-wheat rotation system at RMOR was only 379 kg N ha-1 per year, which result in 21.7% and 36.8% reduction per year in N application compared to Regional Mean Maximal Rate (RMMR) and local N application rate, without negative effect on crop yield and farmers’ net income. Furthermore, RMOR greatly decreased N loss and increased N use efficiency.2. Field and micro-plot experiments were conducted under different N application rates to study the effects of N application rate on N uptake and translocation of two rice cultivars (4007, a new rice cultivar, and Wuyunjingl5, WJ15, a native one). The increases in grain yield with N fertilizer (100,150,200 and 250 kg N ha-1) over the control were 20.6%, 33.6%,37.3% and 34.8% in 4007, while they were 9.41%,14.3%,20.3% and 19.4% in WJ15. N accumulation in rice increased at each growth stage as the enhanced N application rate at both cultivars. The largest N uptake by plants was found between midtillering and initiation and it was 37%-39% of the total N uptake in whole growth period. N translocation to grains increased with enhanced N application rate, ranging from 72.0 kg N ha-1 to 104.4 kg N ha-1 for 4007, and 57.0 kg N ha-1 to 96.5 kg N ha-1 for WJ15, and N translocation efficiency was 66%-51% and 57%-47% for 4007 and WJ15, respectively. 65%-88% of grain N came from the existing N reserves of vegetative tissues acquired before flowering, and only 12%-35% uptaken from soil at reproductive stage. The 15N distribution in grains decreased significantly with increased N application rates, while there was a reverse trend in straw, and no difference in root of both cultivars among the N application rates. The 15N distribution rate in grains of 4007 was much higher than that in WJ15, but lower in straw of 4007 in comparsion with WJ15 under the same N application. Clearly, the higher 15N distribution rate in grains was the main reason for the high grain yield and REN of 4007.3. Fertilizer-N uptake and distribution of rice were studied using 15N tracer technique. 23.1%,8.3% and 19.9% of N uptake in mid-tillering, initiation and anthesis were from 15N labeled fertilizer applied in base (N1), tillering (N2) and initiation (N3), respectively. The 15N translocation from anthesis to maturity was in the order of N3> N1> N2, but the 15N translocation efficiency was higher in N1 (base fertilizer treatment) than in the other two treatments. At maturity, the 15N distribution in straw in the treatments of N1, N2 and N3 was only 24.3%,26.7% and 30.4%, respectively. No matter what time the N fertilizer was applied, the 15N uptake was mostly distributed in leaves, then in the sheath, the least in stem, and 15N distribution in spike increased with the increased 15N translocated from vegetable organs to spike after anthesis. The study also showed that the 15N uptake at maturity in N1, N2 and N3 treatments was 10.6%,5.9% and 12.4%, respectively. The results indicate that when soil N content is not high, the base fertilizer application is important to rice growth, and optimal increment may help increase tillerings, and improve rice quality; the initiation fertilizer significantly promotes quantities during grain filling, and thus application of N fertilizer in initiation is of considerable advance in increasing N harvest index (NHI).4. Effect of applying water surface film-forming material on rice yield, ammonia volatilization, N uptake and utilization were also assessed between the two N application rates of 200 and 250 kg ha-1 in field condition. When 200 kg N ha-1 was applied, water surface film-forming material resulted in little differences in grain yields and ammonia volatilization, but much N uptake in rice leaf and stem before anthesis were found, which was benefitable in N translocation from vegetable organs to seeds in the reproductive growth stage. Accordingly, the N accumulation in seeds (treated by water surface film-forming material) was improved by 13.2% compare to control. When 250 kg N ha-1 was applied, the grain yields in the treatment of water surface film-forming material was increased by 9.9% compared to control and this was mainly contributed by more numbers of tillering. In addition, ammonia volatilization was decreased by 4.15%. Except the tillering stage, higher N uptake was found in leaves and stems during the all growth stage, but no difference was observed in seeds. Whatever the N application rate was, application of water surface film-forming material was benefitable in N accumulation in every part of rice plants, and the total N accumulation was increased by 3.8%-5.9%; Moreover, application of water surface film-forming material could make much more 15N left in the surface of the soil, and make less N lost, and thus contribute a lot to decreased pollution to environment.更多还原