Field experiments were carried out to verify the optimum uncovering plastic film period and nitrogen rate for higher yield, water use efficiency and better physiology, growth condition of maize in mulched fields in the Guanzhong Region, Shaanxi Province and to provide basis for the development of rational cultivation measures. Under field condition, three uncovering plastic film periods (uncovering plastic film at the jointingtasselling stage, uncovering plastic film at the tasselling stage and mulching plastic film) and three nitrogen rates (N 0, 120 and 240 kg/ha) were applied to study the interaction between uncovering plastic film period and nitrogen rate on physiology, growth, yield and water use efficiency of film mulching summer maize. The results show that uncovering plastic film period and nitrogen rate have significant effects on physiology, growth, yield and water use efficiency of summer maize, and the interactive effect between them is not significant. Through improving the gas and heat conditions around the roots, and increasing the root activity, the uncovering plastic film at the tasselling stage increases the plant height, leaf area, and dry mass accumulation and leaf photosynthetic rate, decreases the leaf MDA content, and has better ear characters, yield and water use efficiency in comparison with the mulching plastic film treatment under the three nitrogen rates. However, there are no significant differences between the uncovering plastic film at the jointingtasselling stage and the mulching plastic film treatments. With the same uncovering plastic film period, applying nitrogen fertilizer amounts of NL  (N 120 kg/ha) or NH (N 240 kg/ha) are better than that of the NZ (N 0) treatment in the physiology, growth, yield and water use efficiency of summer maize, however, there are no significant differences between the NH and NL treatments. As the increasing of nitrogen rates, the leaf photosynthetic rate, yield and water use efficiency are decreased, while the leaf MDA content is increased. In this study, taking yield, water and nitrogen use efficiencies and environment effect into consideration, the appropriate uncovering plastic film period and nitrogen rate of summer maize in mulched fields in the Guanzhong Region are uncovering plastic film at the tasselling stage and N 120 kg/ha respectively, the yield and water use efficiency of which are 11362 kg/ha and 34 kg/(ha·mm).

为了探明陕西省关中地区覆膜玉米生理生长、产量及水分利用效率同步提高的最佳揭膜时期和施氮量，制定合理的栽培措施，本试验以关中地区覆膜夏玉米为研究对象，设置3个揭膜时期（拔节抽雄期揭膜、抽雄期揭膜、全生育期覆膜）和3个施氮量（N 0、120、240 kg/hm²），研究了揭膜和氮肥互作对玉米生理生长、产量和水分利用效率的影响。结果表明，揭膜和施氮量均显著影响玉米生理生长、产量和水分利用效率，但两者的互作效应不显著。在3 个施氮水平下，与全生育期覆膜处理相比，抽雄期揭膜可通过改善根际土壤气热条件，提高根系活力，从而增加夏玉米株高、叶面积和地上部干物质量，提高了叶片净光合速率，降低了叶片丙二醛含量，获得较优的穗部性状和较高的籽粒产量及水分利用效率，而拔节抽雄期揭膜处理与全生育期覆膜处理之间无明显差异。当揭膜时期相同时，施氮处理的夏玉米生理生长、产量及水分利用效率等指标均优于不施氮处理，而高氮和低氮处理间无显著差异，但随着施氮量的增加，叶片净光合速率、籽粒产量和水分利用效率呈现减少趋势，叶片丙二醛含量呈现增加趋势。综合考虑产量、水氮高效利用、环境等综合效应，在本试验条件下，陕西关中地区覆膜玉米的适宜揭膜时期为抽雄期、适宜的施氮量为N120 kg/hm²，其籽粒产量和水分利用效率分别为11362 kg/hm²和34 kg/(hm²·mm)。

Wheat production in Northwest China is mainly restricted by insufficient and uneven distributed precipitation across seasons. Besides, luxurious and improper application of nitrogen (N) is an obvious problem. In a two-year field experiment from October 2010 to June 2012, we compared grain yield and N use efficiency of winter wheat with cultivation patterns of conventional fertilization (P), current farmer’s habitual fertilization (C), reducing N with early-spring topdressing (NT), NT + ridging and mulching with plastic film (NR), and NR+ high plant density (NRH). Compared with P treatment, C had no effect on stable increases of grain yield and N use efficiency, while NT, NR, and NRH treatments significantly increased yield and N use efficiency of wheat. However, N content in grain was reduced in NR and NRH treatments. In an overall view, NR was the optimal treatment for high-yield and high-efficient wheat production, with the increases of grain yield, N partial factor productivity, and N physiological efficiency by 38.6%, 49.6%, and 35.1% in the first cropping year and by 7.6%, 16.3%, and 25.7% in the second year, respectively. These results indicate that N management plus ridge mulching is an important technique for high-yield production in Northwest China, and suitable N supply after flowering should be considered for high quality also.

降雨偏少且季节分布不均，施肥偏多且方式不合理，缺少有效的保水栽培措施是西北旱地小麦生产面临的主要问题。2010年10月至2012年6月连续2个小麦生长季，在陕西渭北旱塬进行田间试验，比较了氮肥追施和总量减少、覆膜、增加种植密度措施较传统施肥和农民习惯施肥种植模式对冬小麦籽粒产量及氮素利用效率的影响。与农户习惯施肥相比，传统施肥不能持续增加产量和氮素利用效率；而减氮追肥、减氮垄覆和减氮垄覆增密处理的增产效果明显，同时提高了氮素利用效率，但减氮垄覆或增加种植密度却使籽粒含氮量降低，主要原因是进入开花期后土壤硝态氮累积量减少，氮素供应不足所致。综合分析，减氮垄覆增产增效更明显，小麦产量、氮肥偏生产力、氮肥生理利用率在第1年分别提高38.6%、49.6%和35.1%，在第2年分别提高7.6%、16.3%和25.7%，说明控氮与覆膜结合是实现旱地冬小麦增产的重要措施，但需注意生长后期土壤氮素供应，在增产的同时保证小麦品质。

With the increase of crop yield, topping the highest yield becomes more difficult. Higher productivity requires better crop performance, which accordingly requires precise crop husbandry. However, there are still large gaps in understanding crop performance and their relevant physiological factors and furthermore the effective manipulation measures. As a consequence of which, quantified crop yield analysis is badly needed. On the basis of the secondary structure of “three combination structure” crop yield analysis model, which is the organic integration of photosynthetic property, source sink and yield component theory, the concept of “three combination structure quantitative expression” was put forward, and the parameters were calculated by means of field experiments and simulation method. With that the quantitative expressions of spring maize (Zea mays L.), summer maize, rice (Oryza sativa L.) and winter wheat (Triticum aestivum L.) were founded, respectively. And the causations for high yield and the restrictive factors for higher yield were analyzed. Improving average net assimilation rate (MNAR) would improve rice yield, and properly increasing average leaf area index (MLAI) or harvest index (HI) was the possible way for higher winter wheat yield. The mutative trends of each equation parameter were analyzed for different spring maize populations, the results showed that improving total grain number per unit land area (TGN) via increasing MCGR would result in higher maize yield. The definite function expressions between the parameters were also established. With the definite relationships between the parameters, one parameter can be expressed with other relevant parameter(s). The foundation of the “three combination structure” quantitative expression provided a new idea and new method for the quantitative analysis of crop production. With that one could understand yield formation processes systematically and make a good judgment on the critical factors for limiting higher yield and explore corresponding possible ways to settle them accordingly. So “three combination structure” quantitative expression might be a good guidance for higher crop production.

针对目前作物产量水平长期徘徊难以突破，产量分析理论缺乏量化指标体系，可操作指导作用小等问题，依据“三合结构”模式二级结构层各因素的关系，建立了“三合结构”定量表达式，并通过田间试验与模型模拟相结合的方法，对春玉米、夏玉米、水稻和冬小麦高产实例进行定量化分析，明确了限制产量进一步提高的关键因素，提出了高产突破的可能方向。结果表明，提高叶片平均净同化率（MNAR），改善群体的物质生产能力，是水稻产量进一步提升的关键；适当提高平均叶面积指数（MLAI）或经济系数（HI）可能会进一步增加冬小麦产量；春玉米籽粒产量主要伴随着MLAI和单位面积穗数（EN）的增加而提高，其实质是平均作物生长率（MCGR）的提高增加了单位面积上总粒数（TGN）。进一步研究确定了“三合结构”定量表达式参数间的函数关系式，通过公式代换可推导出某一参数与目标参数的函数关系。作物产量“三合结构”定量表达式的建立为作物群体定量化研究提供了新的思路和方法，有助于全面掌握群体参数变化与产量形成的定量关系，为指导作物生产进行有效的技术调控提供依据。

High yield is an invariable theme in crop science, and the exploration of crop yield potential is a hotspot of crop science researches. While great strides have been made in exploring the breakthrough of crop yield potential, the capability of over-compensation effects was considered to be a potential untouched part for higher grain yield. In this article, the concept, types, functionary effects and mechanisms of crop compensation were commentated, and a broad sense of crop compensation concept was presented on the basis of integrated analysis. Unbalanced changes often taking place in different factors in different hierarchies or same hierarchy, by the function of systemic regulation, some factors could be improved. That is crop compensation. Compensative effects are ubiquitous in crop system, there are not only “gain and loss” compensations in adverse conditions, but also “asynchronous improved” ones in favorable conditions and even sometimes in high yield plant populations. “Gain and loss” compensation was defined as crop could improve some important elements at the cost of depressing or losing its intrinsic performances of some other elements at specific hierarchy. When the crop population and the single plant are almost in perfect harmony, no more gains could be obtained by “Gain and loss” compensation, a new way must be found to break the yield limit. And “asynchronous improved” compensation might be fall back on. In the synchronous improvements of composing elements at specific hierarchy, one lesser improvement of some element might promote a significant improve of other element. This kind of change in crop system was defined as “asynchronous improved” compensation. Once one limited factor was improved, some other factors in crop system might change and a new harmonization at the higher level will be formed, correspondingly the crop yield would increases to a new level. On the basis of crop compensation effects and the “three combination structure” yield theory, two effective approaches, “structural exploration” and “functional exploration”, were put forward and carried out in exploring crop yield potential, and the mechanisms and the application effects of the approaches were expatiated from the overcompensation profile, which would provide an instructive guidance for higher crop yield.

挖掘作物产量潜力，探索作物高产新途径，实现产量新突破一直是作物科学的艰巨任务。本文在分析作物逆境反应的补偿基本规律和机制基础上，提出了作物广义补偿的概念，即作物系统的构成因子间发生不平衡变化，并通过系统调节使得不同程度变化因子之间产生补偿效应统称为作物补偿。按其变化因子间的变化程度不同，可分为得失补偿和差异补偿。得失补偿是指作物系统在一定层次上，有些因子损失原有的性能为代价以换取另外因子的改善和提高，这通常出现在逆境条件中，是作物最普遍最基本的一种补偿。差异补偿是指作物系统在一定层次构成因子共同增效中，增量多的因子与增量少的因子间通过相互作用而获得补偿的特殊现象。作物补偿在补偿效果上可分为超量补偿、等量补偿和部分补偿；在补偿的层次和范围上也表现出多元化的特征，即在作物与环境、作物内部各因子间以及从群落到分子水平各层次均可存在补偿机制。基于作物于广义补偿和产量分析的“三合结构”基本框架，指出作物高产突破是基于得失补偿基础上重点突破差异补偿，所采取的技术途径是结构性挖潜和功能性挖潜，两条途径在作物超高产实践中一直发挥着重要作用。进一步深入研究作物补偿机制及其挖潜途径将更加有力地推动高产突破的进程。

The winter wheat (Triticum aestivum L.)–summer maize (Zea mays L.) rotation is the main crop system in North China plain. In recent years, with continuous increase of air temperature, the double late-cropping system (late sowing for winter wheat and late harvested for summer maize) has of importance for whole-year high yield in this area. Proper scheme of light and heat in the double late-cropping system can provide high resource use efficiency (RUE) and high yields of both wheat and maize. To quantitatively analyze the yield performance and the effect of “double late” we need, two cultivars of winter wheat and two cultivars of summer maize in field experiments in Wen county and Jiaozuo of Henan province in 2006–2007 and 2007–2008 respectively. The dry matter production, grain yield, yield performance quantitative parameters, and energy (light and accumulated temperature) used efficiency were investigated in the double late-cropping system and compared with those in traditional cropping system (control). The results showed that the whole-year yield was 21 891–22 507 kg ha^-1 in the double late-cropping system with 442–2 575 kg ha^-1 more than that in control. In wheat cropping season, the yield of FS230 was slightly reduced with no significant difference form that of the control, but the yield of Yumai 49 significantly (P < 0.05) decreased by 291–305 kg ha^-1. In the maize cropping season, yield increased by 747–2 700 kg ha^-1, which highly compensated the yield loss of winter wheat. In the yield performance quantitative parameters, although the mean leaf area index, spike number, and grain number per spike of winter wheat decreased in the double late-cropping system, the mean net assimilation rate, harvest index, and grain weight were significantly (P < 0.05) promoted. Similarly, the mean leaf area index, harvest index, growth duration, and grain weight of maize significantly increased in the double late-cropping system. The light and temperature use efficiency were 2.22%–10.86% and 0.47%–11.56% higher in the double late-cropping system than in control. The results imply that the double late-cropping system has good performances on grain yield and resource use efficiency. The high whole-year yield and high production efficiency in double late-cropping system are mainly subject to the cropping season of maize, a C₄ plant with high photosynthetic efficiency. Thus, based on late sowing, early-maturing wheat cultivars are suggested to be used in the double cropping system in North China, resulting in longer grain-filling period of the following maize crop and ultimately higher yield.

为了进一步明确黄淮平原冬小麦晚播、夏玉米晚收的“双晚”增产及资源高效的效应，选用2个中熟冬小麦品种和2个中晚熟夏玉米品种，于2006—2008年先后在河南温县和焦作进行大田试验，研究作物群体物质生产、产量形成参数定量指标及光温资源的分配利用。结果表明，冬小麦晚播产量降低不明显，夏玉米晚收产量显著提高747~2 700 kg hm^-2，“双晚”周年产量21 891~22 507 kg hm^-2，比对照提高442~2 575 kg hm^-2。冬小麦晚播平均叶面积指数、每平方米穗数和穗粒数降低，但平均净同化率、收获指数和粒重提高达5%显著水平；夏玉米晚收平均叶面积指数、收获指数、生育期天数和粒重均显著提高。“双晚”栽培优化了周年资源分配，提高生育期与光、温资源变化的吻合度，其生产效率分别提高2.22%~10.86%和0.47%~11.56%。小麦和玉米品种的遗传类型是影响“双晚”栽培技术的关键。因此，选用小麦晚播早熟高产和玉米长生育期晚熟品种，通过有效调节资源配置，将小麦冗余的光温资源分配给C₄高光效作物玉米，是提高周年高产高效的重要途径。

A 2-year field trial using high yield varieties Zhengdan 958 and Zhongdan 909 with densities and tillage systems was conducted in Xinxiang, Henan Province during 2010–2011 growing season to study the characteristics of yield performance parameters and the effect of main cultivation practices for high yield population Results indicated that compared with Zhendan 958, Zhongdan 909 increased grain yield by 11.36% significantly, as well as kernel number per ear (KN) and 1000-kernel weight (KW) (P<0.01). There was no difference (P>0.05) in duration (D), harvest index (HI), and ear number (EN) between two hybrids. Mean leaf area index (MLAI) and leaf area duration were improved significantly (P<0.01), mean net assimilation rate (MNAR) was increased significantly (P<0.05). Moreover, Zhongdan 909 retained higher maximum growth rate,biomass at the maximum growth rate,average growth rate and active growth duration compared with Zhengdan958. There were significantly positive correlations between EN and MLAI (P<0.01), and between KN, KW, and MNAR (P<0.01). There were significantly negative correlations between MNAR, KN, KW, and MLAI (P<0.01). Zhongdan 909 had a higher yield because of the mechanism of asynchronous improvement of yield performance parameters. The optimize population of Zhongdan 909 was 27.3% higher than that of Zhengdan 958, with the higher MLAI, MNAR and KN. Grain yield increased by 8.71% and 13.02% in sub-soiling tillage system for Zhengdan 958 and Zhongdan 909, respectively, resulting from increasing MNAR and KN significantly. There was no difference in MLAI and D between both varieties. HI, EN and KW were increased differently in different varieties. Thus, yield performance parameters for high yield of 11 250–12 000 kg ha^-1 were MALI 3.05–3.55, MNAR 4.80–6.27 g m^-2 d^-1, growth days 109–111, harvest index 0.50–0.52, harvest ears 9.60–10.38×10⁴ ha^-1, kernel number per ear 352.0–370.1, 1000-kernel weight 314.7–315.9 g. Increasing population density (about 9.50×10⁴ plants ha^-1) with sub-soiling tillage system is one of main management practices for high yield in Yellow Huai Valley areas.

以现代高产玉米品种中单909和郑单958为试验材料, 于2010—2011年在河南新乡设置种植密度与耕作方式田间试验, 研究夏玉米高产群体产量性能参数变化及主要栽培措施调控效应。结果表明, 中单909相比郑单958显著增产11.36%, 穗粒数(KN)、千粒重(KW)极显著增加(P<0.01), 生育天数(D)、收获指数(HI)和收获穗数(EN)无明显差异(P>0.05); 平均叶面积指数(MLAI)、光合势在灌浆后期增加更为显著, 平均净同化率(MNAR)显著增加(P<0.05), 而干物质积累最大生长速率、生长速率最大时的生长量、平均生长速率、活跃生长期均明显提高。进一步分析产量性能参数间相互关系, EN与MLAI呈极显著正相关(P<0.01), KN和KW与MNAR呈极显著正相关(P<0.01), 而MNAR、KN、KW与MLAI呈极显著负相关(P<0.01)。中单909比郑单958增产可能是产量性能参数差异补偿的结果。中单909在高密度下具有较高的MLAI、MNAR和KN, 获得最高产量的群体密度比郑单958高27.3%; 深松耕作方式下, 中单909和郑单958分别增产13.0%和8.7%, 主要表现为, MNAR和KN显著增加, MLAI和D无明显变化, HI、EN、KW增加幅度在不同品种间表现不一致, 表明土壤深松条件下密植(9.50×10⁴株 hm^-2)是目前夏玉米高产重要技术途径之一。综上, 密植夏玉米高产群体产量性能特征参数为MLAI 3.05~3.55、MNAR 4.80~6.27 g m^-2 d^-1、D 109~111、HI 0.50~0.52、EN 9.60~10.38×10⁴穗 hm^-2、KN 352.0~370.1粒、KW 314.7~315.9 g, 可以实现11 250~12 000 kg hm-2以上的产量。

Leaf Area Index (LAI) simulation models is an indispensable tool for supporting crop scientific research, population and community growth analysis, and crop management. However, LAI is very difficult to be quantified properly, owing to ecological and varietal factors and temporal variability. Many methods have been developed to quantify LAI and yielded good results, but most of them have different formats with many parameters, which hamper their application. In this paper, an extensively suitable LAI simulation model, y= (a+bx) / (1+cx+dx²), was developed with normalized LAI and crop growth duration data. And by means of which, the specific normalized models y= (0.0134+0.3234x) / (1－2.774x+2.4178x²) for spring maize (r=0.9858**), y= (0.0777+0.0205x) / (1－2.7374x+2.0484x²) for rice (r=0.9865**), and y= (0.0131+0.0035x) / (1－2.4515x+1.5273x²) for winter wheat (r=0.9719**) were established. Compared with other LAI simulation models, normalized LAI dynamic model can not only generate reliable prediction for the evolution of LAI, but also estimate leaf area duration (LAD) and LAI in any period. Once the crop life span and a total leaf area of a crop population in any moment are acquired, the crop LAI and LAD can be estimated easily. From the time of jointing stage, the model could make a good pre-estimation of LAI dynamics with the accuracy of 1.050, 1.0357, and 1.1168 and the precision (R²) were 0.8728, 0.9270, and 0.9254 for spring maize, rice and winter wheat, respectively. Compared with the measured values, the simulated LAI had a linear coefficient (k) over 0.98, with R² above 0.86. The results showed that normalized LAI dynamic model provided a better description for crop population dynamics. Combined with dry matter accumulation, the average LAI, NAR (net assimilation rate), and CGR (crop growth rate) can be calculated. By means of which, the relationships between the physiological parameters and crop yield were analyzed, and the possible ways for higher crop yield were put forward accordingly.

针对目前已有群体叶面积指数（LAI）模拟模型形式多样、参数较多以及应用性不强等问题，对春玉米、水稻和冬小麦的LAI及出苗至成熟天数进行归一化处理，分别将最大LAI和出苗至成熟天数定为1，以相对LAI (0~1)和相对时间(0~1)为参数进行LAI动态模拟，筛选、建立了一个适用于这3种作物的相对化LAI动态模拟模型y= (a+bx) / (1+cx+dx²)。其中，春玉米y= (0.0134+0.3234x) / (1－2.774x+2.4178x²)，r=0.9859**；水稻y= (0.0777+0.0205x) / (1－2.73744x+2.0484x²)，r=0.9865**；冬小麦y= (0.0131+0.0035x) / (1－2.4515x+1.5273x²)，r=0.9719**。利用该模型，自拔节期起就能够较准确地进行LAI的动态预测，其在春玉米、水稻和冬小麦上的准确度（以k表示）分别为1.050、1.0357和1.1168，精确度（以R²表示）分别为0.8728、0.9270和0.9254。3种作物整个生育期内模型的模拟值与测量值的精确度均在0.98以上，准确度达0.86以上，表明相对化LAI动态模型能够准确地反映作物群体动态变化。不仅可以计算出作物生育期间的平均LAI、总光合势，还能计算任一时刻的LAI以及任一时段的光合势。结合田间调查还可得到作物生长期间的平均净同化率和平均作物生长率等产量相关的重要生理参数。根据作物群体中各光合生理参数与产量的关系，提出了3种作物进一步增产的可能途径。

Many researches have shown that the absorption, translocation and utilization of nitrogen varied markedly in different genotypes of common corn. However, there are few reports on waxy corn is this field. In this study, 31 cultivars of waxy corn (Zea mays L. ceratina Kulesh) released recently within China were employed to evaluate their nitrogen use efficiencies (NUE) by indices of agronomic efficiency (AE), recovery efficiency (RE), physiological efficiency (PE), and partial factor productivity (PFP). The field experiment was split plot design with nitrogen treatment (225 kg N/ha) or control (0 kg N/ha) as main factor, and the 31 cultivars were planted randomly in each plot. Five plants of each cultivar were sampled at anthesis, fresh ear harvest (21 days after anthesis) and physiological maturity stages, respectively for measuring nitrogen contents in different organs of leaf, leaf sheath, culm, tassel, bracteal leaf, ear axis and kernel. Results showed that there were significant genotype differences of N use efficiencies among the 31 cultivars in terms of AE, RE, PE, and PFP (Table 2–4). Cluster analysis revealed that the cultivars with high yield potential and NUE for whatever product of fresh ear, fresh kernel or maturity kernel were FN 2146, JKN 267, JKN 218, YBN 1, SW42 and SAUWX02 (Fig.1). Compared with other cultivars, their average yields of the fresh ear, fresh kernel and maturity kernel were higher by 17.9%, 18.1% and 28.6%, the average AEs of the fresh ear, fresh kernel and maturity kernel were higher by 45.2%, 50.2% and 64.7%, the average REs of the fresh ear, fresh kernel and maturity kernel were higher by 35.1%, 35.1% and 36.7%, the average PEs of the fresh ear, fresh kernel and maturity kernel were higher by 4.5%, 9.7% and 20.3%, and the average PFPs of the fresh ear, fresh kernel and maturity kernel were higher by 17.9%, 18.1% and 28.6%, respectively. It is confirmed by correlation analysis that increasing the N harvest index and N translocation rate may promote NUE in waxy corn.

以近年育成的31个糯玉米(Zea mays L. ceratina Kulesh)品种为试材，对其氮肥吸收利用率(RE)、氮肥生理利用率(PE)、氮肥农学利用率(AE)和氮肥偏生产力(PFP)的差异进行了比较。结果表明，各品种以收获鲜穗、鲜籽粒或成熟籽粒为目的，其AE、RE、PE和PFP均存在显著差异。聚类结果显示，无论收获产品是鲜穗、鲜籽粒还是成熟籽粒，属于高产、高氮肥利用效率(NUE)的品种有6个，即凤糯2146、京科糯267、京科糯218、粤白糯1号、SW42和SAUWX02。与其他品种相比，这6个糯玉米品种的鲜穗、鲜籽粒和成熟籽粒的平均产量分别高17.9%、18.1%和28.6%，平均AE分别高45.2%、50.2%和64.7%，平均RE分别高35.1%、35.1%和36.7%，平均PE分别高4.5%、9.7%和20.3%，平均PFP分别高17.9%、18.1%和28.6%。相关分析表明，提高糯玉米氮收获指数，增加氮素在植株体内的运转率有利于NUE的提高。

为阐明种植密度、氮肥和水分胁迫对不同玉米品种产量形成的影响，选用6个玉米品种，在两种密度(45 000株 hm^-2和75 000株 hm^-2)、两种施氮水平(纯氮112.5 kg hm^-2和337.5 kg hm^-2)和两种水分(前期干旱控水和正常灌水)处理下进行大田试验，调查玉米源库性状的主要生理参数和籽粒产量。结果表明，在环境压力较小时(低密度、高氮和正常灌水)，玉米品种间籽粒产量、源性状(叶面积指数、穗位叶净光合速率和群体源供应能力)、库性状(群体库容量)、源库协调性状(群体库源比值、籽粒灌浆速率和收获指数)以及成熟期干物质积累量和吐丝期至成熟期干物质积累量差异较小，而逆境胁迫下(高密度、低氮和干旱)，差异较大。环境压力较大时(高密度、低氮和干旱)，叶面积指数、群体源供应能力、成熟期干物质积累量、吐丝期至成熟期干物质积累量、群体库容量和收获指数与籽粒产量呈显著或极显著正相关。由此说明，在玉米品种产量改良中要强化逆境人工选择，以适应自然选择，改善玉米品种逆境下的群体源库性状，增强吐丝期至成熟期叶片的光合生产效率，强源促库，提高逆境下的生产能力和适应性。

Abstract

SPAD and Dualex readings are accepted as indicators of estimation nitrogen (N) nutrient status in crops. To investigate suitable N topdressing amount in corn (Zea mays L.), the N nutrient status of corn under treatments with different N application rates were evaluated according to SPAD and Dualex readings. The field experiment was carried out in the L'Acadie Experimental Farm at Quebec, Canada from May to October 2008. The plant density was 79,000 plants ha⁻¹, and N fertilizer was applied before sowing (45 kg ha⁻¹) and at jointing stage. N topdressing rates were 0 (N45+0), 34 (N45+34), 68 (N45+68), 101 (N45+101), 135 (N45+135), 169 (N45+169), and 203 kg ha⁻¹ (N45+203), and the N-saturated reference (SAT225) received topdressing N amount of 180 kg ha⁻¹ at 10 d after sowing in addition to basal N application. The SPAD and Dualex readings were obtained from 11 to 46 d after silking at a 6-8 d interval. The SPAD reading, dry biomass of aboveground parts, and corn grain yield increased with more N applied, but the Dualex reading showed a decrease trend. The SPAD-N saturation indices (SPAD-NSIs) for N45+101, N45+135, N45+169, and N45+203 treatments were larger than 0.95 at all sampling dates. The Dualex-NSIs of N45+101 at 18-46 d after silking and N45+135, N45+169, and N45+203 at all sampling dates were larger than 0.95. The SPAD reading, Dualex reading, SPAD-NSI, and Dualex-NSI were highly correlated with N topdressing rates. The maximum yield was obtained in N45+101 or N45+135 treatment, and even more N application had no significant effects on SPAD and Dualex readings, dry biomass of aboveground parts, and grain yield of corn. Thus, under the experimental condition and basal N application of 45 kg ha⁻¹, N topdressing at jointing stage with 101 or 135 kg ha⁻¹ can meet the N requirement of corn for normal growth after silking and maximum grain yield. The integration of SPAD and Dualex is applicable in evaluating in-season N status of corn.

摘要

为了探讨玉米生长过程中适宜的施氮量, 以加拿大玉米品种Pioneer 38B84为试验材料, 在底施氮为45 kg hm⁻¹和基本苗7.9万株 hm⁻¹条件下, 研究追氮量0、34、68、101、135、169和203 kg hm⁻¹以及氮饱和参考小区等8个处理对吐丝后玉米穗位叶SPAD值、Dualex值、地上部生物量及产量的影响。结果表明, SPAD值、地上部生物量以及产量均随追氮量增加而增加, Dualex值随追氮量增加而降低。追氮101、135、169和203 kg hm⁻¹处理的SPAD-氮饱和指数(SPAD-NSI)在各测定日期均大于0.95。追氮101 kg hm⁻¹处理的Dualex-NSI在吐丝后18∼46 d大于0.95; 追氮135、169和203 kg hm⁻¹各处理的Dualex-NSI在各测定日期均大于0.95。SPAD 值、Dualex 值、SPAD-NSI和Dulaex-NSI均与追氮量显著相关。在拔节期追氮101 kg hm⁻¹ 或135 kg hm⁻¹即可满足玉米生长对氮素的需求, 获得最大的经济产量。当超过最大产量施肥量时, 氮肥用量的增加对SPAD值、Dualex值、地上部生物量以及产量均无显著影响。追肥不仅可达到与氮饱和参考小区同样的产量效果, 而且还可减少氮肥的施用量, 减少种植者的经济投入。在本试验条件下, 基施氮45 kg hm⁻¹, 在拔节期适宜的追氮量为101 kg hm⁻¹或135 kg hm⁻¹。SPAD叶绿素仪与Dualex仪均可用来诊断玉米的氮素营养状况。

Application of nitrogen (N) fertilizer is one of the most important measures to increase grain yield and protein content in winter wheat (Triticum aestivum L.) production. However, misuse of N fertilizer will not only affect grain yield and quality, but also cause the decline of economic effects and related environmental effects. It is essential to study reasonable nitrogen applying regimes for profitable yields, efficient N utilization, and reduction of possible environment pollution. The objectives of this study were to determine the N uptake and translocation in wheat plant by using 15N isotope tracer in PVC cylinders (2.05 m length, Ф0.2 m, without bottom) with seven treatments: without applying N fertilizer (N0); N application rate of 168 kg N&#903;ha^-1 (0.527 g/pot), ratios of base fertilizer to topdressing of 1:1 (N1), 1:2 (N2) and 0:1(N3); N application rate of 240 kg N&#903;ha^-1 (0.753 g/pot), ratios of base fertilizer to topdressing of 1:1(N4), 1:2(N5) and 0:1(N6). Treatment N4 is a regime applied now in local wheat production. At the same time, the field experiment was conducted in the same field, and experimental design is same as that of the 15N isotope tracer experiment with three repetitions. The plot area was 3 m×8 m=24 m². At the three-leaf stages, the seedlings were thinned to a density of 150 plants per m².
¹⁵N tracer experiment showed that main basal nitrogen absorbed by plant from sowing to jointing stage accounted for 78.04%–89.67%; fertilizer-N use efficiency (N fertilizer accumulation in plant/N supplied, FNUE) of topdressing was markedly higher than that of basal nitrogen; reducing basal nitrogen amount and increasing topdressing nitrogen amount could appropriately promote plant to absorb more fertilizer nitrogen, and enhance FNUE, of which treatment N2 was the highest. In high-yield condition this study concerned, when nitrogen (N) fertilizer rate increased from 168 kg·ha^-1 to 240 kg·ha^-1, the amount of N accumulation in plant and in grain had no significant difference between treatments with the same ratio of base fertilizer to topdressing; with reducing basal nitrogen amount and increasing topdressing nitrogen amount appropriately, the translocation efficiency (accumulation amount from vegetative organs to grain/N accumulation in vegetative organs on anthesis, TE) heightened, and the amount of nitrogen assimilation for grain after anthesis and its contribution proportion (the amount of nitrogen assimilation to grain after anthesis/N accumulation in grain) also increased, in other words grain N accumulation amount increased with increasing amount of topdressing nitrogen in the same nitrogen fertilizer rate. There was no significant difference among treatments N2, N3, N5 and N6 in grain nitrogen accumulation. Appropriate N fertilizer rate with reducing basal nitrogen amount and increasing topdressing nitrogen amount such as in N2, N5 and N6 increased grain yield and protein content. In conclusion, under the condition of this experiment, as far as grain yield, protein content and fertilizer-N use efficiency are concerned, the most appropriate nitrogen fertilizer applying regime recommended is treatment N2, its nitrogen fertilizer rate is 168 kg·ha^-1 and ratio of base fertilizer to topdressing is 1:2.

应用¹⁵N示踪技术研究了高产麦田中施氮量和底施与追施氮肥的比例对小麦氮素吸收转运及籽粒产量的影响。共设7个处理，对照为不施氮肥(N0)；在施纯氮量为168和240 kg/hm²条件下，各设底肥氮量与追肥氮量比例（底追比例）为1∶1 (N1和N4)、1∶2 (N2和N5)、0∶1(N3和N6)。结果表明，播种至拔节期植株积累的底施氮占植株全生育期积累底施氮总量的78.04%~89.67%；小麦植株对追肥氮的利用率显著高于对底肥氮的利用率，适当增加追施氮肥的比例可提高氮肥利用率，其中N2处理的最高。在相同底追比例下，不同施氮量处理相比较，植株与籽粒中的氮素积累量均无显著差异；施氮量相同，随追施氮肥比例的增加，开花前贮存氮素的转运量和转运效率呈先增加后降低的趋势，N2和N5的转运量及转运效率最高；开花后氮素的同化量及对籽粒的贡献率则随追施氮比例的增加而提高；籽粒氮素积累量在N2、N3、N5和N6处理间无显著差异，但显著高于N1和N4。适量施氮并增加追施氮肥的比例可显著提高籽粒产量、蛋白质含量，N2、N5和N6均效果较好。在本试验条件下，施氮量为168 kg/hm²及底追比例为1∶2的处理是兼顾产量、品质和效益的最佳氮肥运筹方式。