Agronomic Assessment of Nitrogen Use Efficiency in Spring Wheat and Interrelations with Leaf Greenness Under Field Conditions

Four spring wheat genotypes (Triticum aestivum L.) were grown without (N0 = 0 kg N ha^?1) and under ample (N1 = 250 kg ha^?1) nitrogen (N) fertilizer in field experiments in two seasons. The aim was to assess genotypic variation in N use efficiency (NUE) components and N-related indices during grain filling thus to identify superior wheat genotypes. Leaf chlorophyll (SPAD) readings at crucial growth stages were employed to help differentiate genotypes. Interrelations between yield and N-related indices with SPAD, where also assessed to explain possible pathways of improving NUE early in the growing season. Results showed that genotypic effects on NUE were mostly evident in 2000, a year with drier preanthesis and wetter postanthesis than the normal periods. ‘Toronit’ almost always had the highest biomass yield (BY) and grain yield (GY). Except in 1999 under N0, ‘L94491? showed the highest % grain N concentration (GNC). Genotypes affected SPAD at almost all stages and N fertilization delayed leaf senescence for all genotypes and growth seasons. Correlations between SPAD at different growth stages and GY, N biomass yield at maturity (NBYM) and GNC were significant (P≤ 0.001), positive and strong/very strong (>r = 0.7). N translocation efficiency (NTE) was inversely related to PANU (~r = ? 0.77, P≤ 0.001), suggesting that N after anthesis is being preferentially transported to the ears to meet the N demand of the growing grains. It is concluded that there is still a large potential for increased NUE by improved N recirculation, use of fast and inexpensive crop N monitoring tools and high yielding, N uptake efficient genotypes.

Abbreviations: NUE, Nitrogen use efficiency; SPAD, Minolta SPAD-502 chlorophyll meter, NHI, nitrogen harvest index; HI, Harvest index; NTE, N translocation efficiency from vegetative plant parts to grain; DMTE, dry matter translocation efficiency; CPAY, contribution of pre-anthesis assimilates to yield; PANU, Post-anthesis N uptake, d.a.s., days after sowing, N0, zero (0) kg ha^?1 applied N fertilizer, N1, 250 kg ha^?1 applied N fertilizer.     

优化施肥对陇东旱塬宽幅沟播冬小麦产量、氮肥及水分利用的影响

为探索陇东旱塬冬小麦高产高效绿色栽培新模式，以冬小麦品种陇鉴111为指示品种，采用裂区设计，以宽幅沟播和平作条播为主区，优化施肥和不施氮肥为副区，研究了宽幅沟播对陇东旱塬冬小麦产量、氮肥及水分利用效率的影响。结果表明，宽幅沟播显著影响旱地冬小麦籽粒穗粒数、千粒重、穗粒重等产量构成因子，较传统平作条播平均增产10.3%~24.3%，且以推荐优化施肥(N 150 kg/hm2、P2O5 180 kg/hm2)增产效果明显。与传统平作条播相比，可促进冬小麦植株氮素养分吸收，氮肥偏生产力和氮肥农学效率分别显著增加6.81、4.30 kg/kg，氮肥利用率明显提高了9.6百分点，水分利用效率提高了9.5%~19.6宜种植模式，以推荐优化施肥N 150 kg/hm2、P2O5 180 kg/hm2效果明显。     

追氮和垄膜沟播种植对晋南旱地冬小麦氮素利用的影响

在自然降水条件下,通过2年大田试验研究了追氮、垄膜沟播种植对晋南旱地冬小麦生育期地上部氮素吸收累积,02 m土层氮素残留、损失及氮肥利用率和氮素平衡的影响。结果表明: 追氮和垄膜沟播种植均可显著提高旱地冬小麦地上部氮素累积量和氮肥利用率,苗期和返青至抽穗期是冬小麦氮素吸收累积的两个高峰期,分别占到最大累积量的20%46%和29%57%。追施氮的利用率高于基施氮的利用率; 随施氮量增加,土壤残留无机氮（Nmin）增加,主要集中在060 cm土层,2040 cm土层为硝态氮积累的峰值区,垄膜沟播种植可以减少土壤残留无机氮（Nmin）,但增加了氮的表观损失量; 冬小麦生长季土壤氮输出以表观损失为主,氮肥表观损失率在4087%7629%之间,且主要发生在播前至返青期。本试验条件下,综合氮素吸收累积、土壤残留、氮肥利用率及氮素平衡等因素,旱地冬小麦应采取氮肥后移顶凌追施和垄膜沟播相配套的种植方式。     

Wheat Yield Differences between Two Cropping Systems in Permanent Raised-Beds as Affected by Components of Nitrogen Use Efficiency

Permanent raised-bed is an alternative planting system for wheat (Triticum aestivum L.) in rain-fed areas. However, this system in monoculture conditions produces lower yields compared with wheat in rotation. Our objective was to estimate these yield differences as affected by nitrogen (N) use efficiency (NUE). Wheat in monoculture and in rotation with maize (Zea mays L.) was evaluated for eight years (2002–2009) with four N rates (0, 40, 80 or 120 kg ha^?1). Yield response to N in monoculture was consistently lower than for wheat in rotation. Yield reduction in monoculture at low and high N rate was 81 and 99% attributed to NUE out of which 70 and 82% was due to the uptake efficiency (UPE) and 30 and 19% to the utilization efficiency (UTE), respectively. Total N uptake proved to be the parameter that needs to be improved to enhance wheat yield in monoculture.

Abbreviations: NUE: nitrogen use efficiency; UPE: uptake efficiency; UTE: utilization efficiency; Ns: nitrogen supply; NDVI: normalized difference vegetation index     

川东北麦秆还田对水稻氮素吸收转运的影响

为合理利用秸秆,于2014和2015年两个水稻生长季,在大田条件下,以当地平均施肥量为标准,设置不同量的化肥配施秸秆处理,研究秸秆还田下水稻氮素吸收转运特征。结果表明:较纯化肥处理,秸秆替代一部分氮肥处理对水稻产量、地上部氮素积累量、氮素收获指数及氮肥生产效率无显著影响(P0.05);在不同程度上降低氮素在穗部的分配比例、营养器官吸收氮素向穗部转运量、转运率、转运氮对籽粒氮素贡献率;在不同程度上提高成熟期营养器官氮素积累量,显著提升抽穗后氮素吸收量及其对籽粒氮素贡献率(P0.05)。综合氮素吸收转运及利用效率,川东北稻麦轮作区水稻季在化肥减施30%基础上,麦秆还田量以6 000 kg/hm~2为宜。     

Long-Term Effects of Nitrogen Management Practices on Grain Yield,Nitrogen Uptake,and Efficiency in Irrigated Corn

ABSTRACT

Crop management strategies that improve Nitrogen Use Efficiency (NUE) increase profits while reducing the detrimental effects on the environment associated with fertilizer nitrogen (N) loss. Effective N management should include several critical factors that are very interrelated. A study was conducted at the Panhandle Research and Extension Center, Goodwell, OK to evaluate the effects of multiple nitrogen management practices including N rate, source, time of application, methods of fertilizer and residue incorporation over a long period of time on grain yield, N uptake and NUE in irrigated corn. Fourteen treatments were evaluated in a randomized complete block design with three replicates. Results of data analyzed on the individual year and averages of all years showed that grain yield and N uptake were improved with N rates and N management practices compared to checks. Both N recovery and efficiency of use were high for the 118 kg N ha^{? 1} rate.     

Phosphorus Enriched Organic Amendments can Increase Nitrogen Use Efficiency in Wheat

Although nitrogen (N) has the highest requirement for plant growth, N use efficiency (NUE) seldom exceeds 40%. NUE may be improved by integrated application of fertilizer N and enriched organic amendments. The present experiment aimed to test the extent of increase in NUE by integrated application of fertilizer N farmyard manure (FYM) and rock phosphate enriched compost (RPEC). Mineralization kinetics and N release from FYM and RPEC were studied by an incubation experiment. Results revealed that maximum potentially mineralizable N as well as N release (283.9, 186.7 mg kg^?1 soil, respectively) were from RPEC + fertilizer N treated soils, followed by FYM + fertilizer N. Maximum yield, N uptake, and N recovery were obtained from RPEC + fertilizer N treated soils followed by FYM + fertilizer N. Soils treated with RPEC had shown significantly higher dehydrogenase activity than FYM treated soils. Thus, RPEC might increase yield as well as NUE over FYM. N uptake by plant at maximum tillering stage and flowering stage of wheat correlated positively (R² > 0.85) with the decay rate (k and kN₀) parameter of incubation experiment suggesting their relevance as indicators of plant available N.     

不同品种油菜子粒产量及氮效率差异研究

采用大田试验,以16个冬油菜品种为试验材料,系统研究了油菜子粒产量、氮素吸收量、氮素响应度和氮素利用效率的品种间差异,并初步探讨了氮素吸收效率和氮素利用效率对不同品种油菜氮效率差异的贡献。结果表明,无论施氮水平如何,不同品种的子粒产量、氮素利用效率和氮素响应度均有显著差异,而氮素吸收量只有在不施氮条件下品种间差异才达到显著水平。根据不施氮时的氮效率和氮素响应度将16个油菜品种分为4种不同类型:1）氮高效–高氮响应（NHE-NHR）型,包括Xy1、Xy16、Xy17、Xh19、Xh20和Xy21; 2）氮低效--低氮响应（NLE-NLR） 型,包括Xy6、Xy8和Xy9;3）氮高效–低氮响应（NHE- NLR）型,包括Xy7、Xy12、Xy14、Xy15和Xy24;4）氮低效–高氮响应（NLE-NHR） 型,包括Xy11和Xy13。无论供氮水平如何,氮素利用效率的变异系数均大于氮素吸收效率的变异系数,说明氮素利用效率对油菜氮效率差异的贡献大于氮素吸收效率。但是,氮素吸收效率的变异系数不施氮时大于施氮条件,氮素利用效率的变异系数则相反,说明在氮胁迫条件下,氮效率的差异中来源于氮素利用效率的变异减少,来源于氮素吸收效率的变异增加。     

SUBSOIL ROOT GROWTH OF FIELD GROWN SPRING WHEAT GENOTYPES (TRITICUM AESTIVUM L.) DIFFERING IN NITROGEN USE EFFICIENCY PARAMETERS

In a two-year (1999–2000) field experiment four Swiss spring wheat (Triticum aestivum L.) genotypes (cvs. ‘Albis’, ‘Toronit’ and ‘Pizol’ and an experimental line ‘L94491’) were compared for genotypic differences in the root parameters that determine uptake potential and nitrogen use efficiency (NUE):root surface area (RSA) and its components, root length density (RLD) and the diameter of the roots. The genotypes were grown under no (N0) and under ample fertilizer nitrogen (N) [ammonium nitrate (NH₄NO₃); N1; 250 kg N ha^?1] supply. Root samples were taken from all the genotypes at anthesis from the subsoil (30–60 cm). Genotypic effects on RLD and RSA were evident only in 2000 and large amounts of N fertilizer usually diminished root growth. Adequate soil moisture in 1999 may have favored the establishment of the root system of all the genotypes before anthesis. Parameters of NUE for each genotype were also determined at anthesis and at physiological maturity. ‘Albis’ the least efficient cv. in recovering fertilizer N (ranged from 36.5 to 61.1%) with the lowest N uptake efficiency (0.47 to 0.79 kg kg^?1) had the lowest RLD and RSA in both seasons. Among genotypes ‘Toronit’, a high-yielding cv., efficient in recovering fertilizer N, exhibited the higher NUE (22.4 to 29.3 kg kg^?1) and tended to have the highest values of RLD and RSA. Nitrogen fertilization also led to an increase in the proportion of roots with diameters less than 300 μm and decreased the proportion of roots with diameters of 300 to 700 μm. These trends were more pronounced for cv. ‘Pizol’ in 1999 and for cv. ‘Toronit’ in 1999 and 2000. By anthesis in a humid temperate climate, there are no marked differences in the subsoil root growth of the examined genotypes. Some peculiarities on the root growth characteristics of the cultivars ‘Albis’ and ‘Toronit’ may partially explain their different NUE performance.     

野生大麦氮素吸收利用的基因型差异

采用土培盆栽,研究16份野生大麦在同一低氮处理下全生育期氮素吸收利用的基因型差异,旨在筛选出具有高效利用氮素能力的基因型,为氮素高效利用大麦育种提供种质材料。结果表明：（1）生物量、氮含量和氮素利用效率的基因型差异最大都在抽穗期（CV=33.55%,18.93%,21.88%）,氮含量和氮素利用效率基因型差异拔节期最小...     

黄土高原旱地小麦施肥对产量及水肥利用效率的影响

在长期定位试验的基础上,研究了黄土高原旱地不同施肥对小麦产量、土壤养分和水分的变化及其利用效率的影响。结果表明,单施有机肥(M)增产效果较好,产量达5265.0 kg/hm2;有机肥和化肥配施(NPM)小麦产量最高,达5898.8 kg/hm2。NPM配施小麦总吸氮量最大,比单施氮肥(N)增加了131.4 kg/hm2;NPM配施的氮肥利用率、氮肥偏生产力、氮肥农学效率、氮肥生理利用率分别为67.0%、49.16 kg/kg、36.97 kg/kg、73.11kg/kg;在不同施肥体系中其变化趋势基本一致,均为:NNPNMNPM,处理间差异显著。土壤养分含量变化看出,单施氮肥土壤全氮、碱解氮与不施肥(CK)的差异不显著;有机肥可显著提高土壤速效钾的含量;NPM配施土壤耗水量最大为558.3 mm,水分利用率最高为31.5 kg/(hm2.mm),随着耗水量增加的同时,土壤出现干燥化趋势。     

不同类型氮肥与施氮量下夏玉米水、氮利用及土壤氮素表观盈亏

以两个夏播玉米品种为材料，研究了不同类型氮肥与不同施氮量下华北平原夏玉米的水分与氮素利用及土壤氮素表观盈亏．结果表明：（1）随施氮量增大．产量、耗水量及水分生产效率（WPE）增大，氮肥利用率（NUE）降低；（2）夏玉米WPE与NUE具有较明显的基因型差异。WPE郑单958较大。NUE农大108较大；（3）wPE与NUE均受到氮肥类型的影响．WPE郑单958复合肥〉普通尿素〉包膜尿素．农大108处理间差异较小，以复合肥略大，普通尿素和包膜尿素相当。与普通尿素相比，包膜尿素与复合肥利用率较高，郑单958施N90kg／hm^2与农大108施N180kg／hm^2时，两者对NUE的提高尤为明显；（4）本试验条件下，经过夏玉米生长季，两品种各处理均出现土壤氮素表观亏缺，亏缺量随施氮量增大而降低，各条件下郑单958亏缺量较农大108大；氮肥类型间土壤氮素表观亏缺量表现为复合肥〉包膜尿素〉普通尿素。     

Genotypic Differences in Dry Bean Yield and Yield Components as Influenced by Nitrogen Fertilization and Rhizobia

Dry bean (Phaseolus vulgaris L.) is an important legume worldwide and nitrogen (N) is most yield limiting nutrients. A field experiment was conducted for two consecutive years to evaluate response of 15 dry bean genotypes to nitrogen and rhizobial inoculation. The N and rhizobia treatments were (i) control (0 kg N ha^?1), (ii) seed inoculation with rhizobia strains, (iii) seed inoculation with rhizobia strains + 50 kg N ha^?1, and (iv) 120 kg N ha^?1. Straw yield, grain yield, and yield components were significantly influenced by N and rhizobial treatments. Grain yield, straw yield, number of pods m^?2, and grain harvest index were significantly influenced by year, nitrogen + rhizobium, and genotype treatments. Year × Nitrogen + rhizobium × genotype interactions were also significant for these traits. Hence, these traits varied among genotypes with the variation in year and nitrogen + rhizobium treatments. Inoculation with rhizobium alone did not produce maximum yield and fertilizer N is required in combination with inoculation. Based on grain yield efficiency index, genotypes were classified as efficient, moderately efficient, and inefficient in nitrogen use efficiency (NUE). NUE defined as grain produced per unit N applied decreased with increasing N rate. Overall, NUE was 23.17 kg grain yield kg^?1 N applied at 50 kg N ha^?1 and 13.33 kg grain per kg N applied at 120 kg N ha^?1.     

旱地土壤硝态氮与氮素平衡、氮肥利用的关系

利用长期肥料试验资料研究了土壤氮素平衡、氮肥利用率和土壤硝态氮之间的相互关系。结果表明,小麦不同施肥处理的氮肥利用率（NUE）为30.9%~65.8%,平均53.6%;土壤硝态氮累积率2.3%~44.1%,平均13.2%;氮素表观损失率25.0%~42.7%,平均33.2%。一般情况下,氮素盈余值与氮肥用量呈正相关,与磷肥用量呈负相关;土壤中硝态氮的数量与氮素盈余值呈正比,与氮肥利用率呈反比。黄土旱塬地区,小麦在经济合理施氮条件下,氮素盈余值为13.79 kg/hm2,硝态氮累积量为23.00 kg/hm2,说明过量施用一定数量的氮肥对保持作物生产力和土壤氮素营养是必要的。     

基于15N同位素示踪盐渍化农田向日葵氮素利用规律

为探明盐渍化农田不同施氮水平下向日葵氮素吸收利用规律,采用¹⁵N同位素示踪技术进行田间微区试验,以不施氮处理(N0)为对照,设计3种施氮水平(N1=150 kg/hm²、N2=225 kg/hm²、N3=300 kg/hm²),于向日葵成熟期测定植株和0—100 cm土层土壤¹⁵N同位素丰度及总氮含量,研究各处理肥料氮素的去向及其利用机制。结果表明:向日葵氮素吸收量随施氮量的增加而增加,成熟期作物氮素吸收量在N2水平较不施氮显著增加38.7%;土壤氮和肥料氮对作物当季氮素吸收的贡献比例为84.9%和15.1%。N2水平下,肥料氮的贡献比例较N1增加35.7%,土壤氮的贡献比例较N1降低4.3%。肥料氮残留量随土层深度增加而减少,土壤中47.4%的残留肥料氮主要集中在0—20 cm土层。不同施氮水平下肥料氮去向均表现为氮肥损失率>氮肥残留率>氮肥利用率,N2施氮水平下氮肥利用率较N1、N3显著提高22.7%和14.6%,土壤残留率较N1、N3减少8.5%和8.6%。综合考虑向日葵氮素吸收利用及土壤中氮素残留情况,225 kg/hm²施氮量下氮肥利用率为27.4%,氮肥残留率为32.3%,氮肥损失率为40.3%,是中度盐渍化农田较适宜的施氮量。     

生长模型和15N示踪评价施肥处理对苹果树氮肥利用的影响

为提高果树氮肥利用率，探索一种简便易行的氮肥利用评价方法，该研究以田间5年生延长红（"长富2号"芽变品种）为研究对象，分别采用生长模型和15N示踪技术对比分析不施氮肥（CK）、常规高氮（N800）、优化减氮（N400）和有机无机配施（N200+O200）处理下苹果树对氮肥的吸收利用情况以及各器官氮素的分配特性的差异，结果表明：不同施肥处理对苹果的产量没有显著性的影响（31.7～37.3 t/hm2）；各施氮处理基于生长模型和15N示踪技术的果树氮肥利用率分别为13.13%～31.94%和11.64%～32.40%；基于生长模型，N400和N200+O200处理果树的氮肥利用率比N800处理高84.92%和143.26%；基于15N示踪技术，N200+O200处理的果树氮肥利用率比N800和N400高178.35%和69.28%；不同施肥处理对各器官氮素分配没有显著性的影响。两种评价方法对于果实和叶片的氮肥利用率、各器官氮素的分配情况分别存在显著差异（P<0.05）和极显著差异（P<0.01），但对植株总体氮肥利用率的评价结果无显著差异，平均仅相差3.10%。基于本试验的研究结果可以得出，利用生长模型可以估算苹果树的氮肥利用率。研究结果可为农田管理措施改善以及果树氮肥利用率评价提供理论参考。     

包膜尿素对夏玉米产量、吸氮量和氮分配的影响

以施氮量调控氮代谢,提高氮肥利用率为目标,利用15 N研究了包膜尿素（CU100、150和225kg/hm2）和普通尿素（150和225kg/hm2）对夏玉米产量、生物量、氮肥利用率以及各器官氮分配的影响。结果表明：包膜尿素比普通尿素显著增加玉米从肥料中的吸氮量,显著增加地上部生物量;15N包膜尿素肥料利用率（15NU...     

冬小麦节水灌溉制度下不同施氮量的氮素平衡

用15N示踪技术研究了节水灌溉条件下冬小麦对不同施氮量的氮素吸收和氮素平衡 ,并比较了两种灌溉制度下小麦对节肥施氮量的吸收动态。结果表明 ,与常规施氮量处理相比 ,节水灌溉条件下节肥施氮量处理的氮肥损失率降低 ,氮肥当季利用率和土壤残留率提高 ;基施氮肥的利用率高于追施氮肥 ;土壤肥料氮的残留率在 2 9%～ 41 %之间 ,分布于 1m土层中 ,其中60 %以上集中在 0～ 2 0cm土层 ;在整个小麦生长季内 ,肥料氮并没有淋洗到 1 30m以下。节肥施氮量在常规灌溉下的当季利用率比在节水灌溉下降低 1 6 6%。     

The effect of form and level of inorganic N on nitrogen use efficiency of sugarcane grown in pots

To-date, assessments of nitrogen use efficiency (NUE) of sugarcane have not included the contribution of its components, nitrogen uptake efficiency (NUpE) and nitrogen utilization efficiency (NUtE). This study determined these values, based on biomass and plant nitrogen (N) content, in two four-month-old pot-grown genotypes. The treatments included six N regimes, with nitrate (NO₃^—N) or ammonium (NH₄⁺-N) supplied alone, or as NO₃^?-N for the first 6 weeks and then NH₄⁺-N until harvest, each as 4 or 20 mM. Regardless of the N form, NUE was higher at four than at 20 mM due to significantly higher NUpE at low N supply. The results indicated that there was luxury N uptake and preference for NH₄⁺-N nutrition, which resulted in the highest determined NUE. There were significant differences between genotypes in biomass, morphological growth parameters, N uptake, total plant N and NUE, the latter matching previously established sucrose yield-based NUE field rankings.     

黄土高原氮磷肥水平对旱作冬小麦产量与氮素利用的影响

为了探求氮磷肥合理和高效利用的科学依据,以黄土高原中南部的旱地农田生态系统长期定位试验为基础,选取了不同施氮和施磷水平,探讨了不同降水年份,氮磷肥用量对作物产量、氮素吸收和利用等相关指标的影响。结果表明,平水年份施氮水平在0～45?kg/hm2和干旱年份在0～90?kg/hm2范围内作物产量和收获指数均随施氮水平的增加迅速提高,超过这个范围后则差异较小;施磷水平在0～45?kg/hm2之间产量增幅较大,干旱年份施磷量反而降低了收获指数;吸氮量随氮磷用量变化与产量有相似趋势;不同降水年份施氮水平对氮素收获指数均无显著影响,而施磷水平在干旱年份对氮素收获指数没有显著影响,平水年份则随施磷水平增加而有所提高;平水年份氮素利用效率随施氮水平的增加呈降低趋势,而干旱年份施氮水平对冬小麦氮素利用效率没有显著影响,施磷则在不同降水年份均比不施磷肥的处理提高了冬小麦的氮素利用效率,但较高的施磷水平之间差别较小。冬小麦产量和吸氮量之间有显著相关关系,干旱年份更接近二次曲线,氮素利用效率随吸氮量增加呈直线下降趋势。旱作农田氮磷配施及采用适中的氮磷肥用量可以促进作物对氮素的吸收,同时得到较高的氮素利用效率,从而使冬小麦获得较高的产量和较强抵御干旱的能力。