Effect of Nitrogen Applied Before Transplanting on NUE in Rice

Nitrogen （N） application before transplanting, where N fertilizers are applied in seedling-bed and carried to the paddy field with seedlings, is a novel method proposed in this article aiming for improving nitrogen utilization efficiency （NUE） in rice. The effect of this method on mineral N distribution in the rhizosphere soil was investigated in a field experiment with a japonica variety, Ningjing 2, in seasons of 2004 and 2005. There were four levels of N applied 16 h before transplanting： zero N （NO）, 207 kg ha^-1 （NL）, 310.5 kg ha^-1 （NM）, and 414 kg ha^-1 （NH）. The result indicated that N fertilizer before transplantation had positive effect of increasing mineral N content in the rhizosphere soil of rice. Generally, N content in the rhizosphere soil of rice tended to increase with the amount of N fertilizer before transplanting, with the NH treatment having the largest effect. Additionally, N fertilizer before transplanting had significant influence on rice NUE and grain yield. Compared with other treatments, the NM treatment showed the largest influence, with basal-tillering NUE, total NUE, and grain yield being 15%, 12%, and 529.5 kg ha^-1 higher than those of NO treatment. This result indicated that N fertilizer before transplantation had positive effect on mineral N distribution in the rhizosphere soil of rice, thus improving NUE and grain yield.     

Tiller fertility is critical for improving grain yield,photosynthesis, and nitrogen efficiency in wheat

Genetic improvement has promoted wheat’s grain yield and nitrogen use efficiency (NUE) during the past decades. Therefore, the current wheat cultivars exhibit higher grain yield and NUE than previous cultivars in the Yangtze River Basin, China since the 2000s. However, the critical traits and mechanisms of the increased grain yield and NUE remain unknown. This study explores the mechanisms underlying these new cultivars’ increased grain yield and NUE by studying 21 local cultivars cultivated for three growing seasons from 2016 to 2019. Significantly positive correlations were observed between grain yield and NUE in the three years. The cultivars were grouped into high (HH), medium (MM), and low (LL) grain yield and NUE groups. The HH group exhibited significantly high grain yield and NUE. High grain yield was attributed to more effective ears by high tiller fertility and greater single-spike yield by increasing post-anthesis single-stem biomass. Compared to other groups, the HH group demonstrated a longer leaf stay-green ability and a greater flag leaf photosynthetic rate after anthesis. It also showed higher N accumulation at pre-anthesis, which contributed to increasing N accumulation per stem, including stem and leaf sheath, leaf blade, and unit leaf area at pre-anthesis, and promoting N uptake efficiency, the main contribution of high NUE. Moreover, tiller fertility was positively related to N accumulation per stem, N accumulation per unit leaf area, leaf stay-green ability, and flag leaf photosynthetic rate, which indicates that improving tiller fertility promoted N uptake, leaf N accumulation, and photosynthetic ability, thereby achieving synchronous improvements in grain yield and NUE. Therefore, tiller fertility is proposed as an important kernel indicator that can be used in the breeding and management of cultivars to improve agricultural efficiency and sustainability.     

优化氮素与品种匹配可协同提高盐碱地夏玉米产量和氮肥利用率

【目的】 明确不同耐盐碱型夏玉米品种产量形成及氮素利用特征,挖掘盐碱地玉米氮素高效利用的生物学潜力。【方法】 以耐盐型玉米品种登海605、鲁单818和不耐盐型玉米品种鲁单981、连胜188为供试材料,在不同施氮水平下（0、180和360 kg·hm^-2,记作N0、N1和N2）,系统研究了施氮对不同耐盐碱类型玉米品种物质积累、氮素积累、氮素分配与利用效率及产量形成的影响,并分析了氮肥水平和品种间的互作效应。【结果】施用氮肥可显著提高盐碱地夏玉米籽粒产量,高氮水平下能够提高不耐盐型玉米品种产量潜力。与N1处理相比,N2处理下耐盐型玉米品种产量无显著变化,不耐盐品种LD981和LS188 2年平均显著增产9.93%和16.31%,各品种氮肥偏生产力（NPFP）、氮肥农学效率（NAE）和氮肥利用率（NUE）均显著降低。互作效应分析表明,产量及其构成因素的差异是由品种、氮肥水平及品种和氮肥水平之间的互作效应共同作用的结果。不同氮肥水平下,耐盐型品种比不耐盐品种分别增产7.78%—27.63%（N0）、7.40%—24.87%（N1）和0.32%—9.55%（N2）;氮肥利用效率（NUE）分别提高26.65%—48.28%（N1）和1.20%—24.87%（N2）。【结论】耐盐型品种较不耐盐型品种具有较高的物质生产和氮素吸收利用能力,在低氮下具有较高的产量优势,而不耐盐型品种在高氮水平下有利于产量的发挥。施氮量、品种及其互作效应通过影响干物质积累量、产量和氮素吸收转运影响氮肥利用效率,优化氮肥供应与品种匹配,能够实现盐碱地玉米产量与氮肥利用效率的协同提高。     

江西鹰潭地区早稻氮素营养光谱诊断模型的构建与应用

 【目的】建立基于水稻冠层归一化植被指数NDVI的早稻氮素诊断模型,并利用模型指导水稻生产实践,实现水稻氮素追肥的精确定量。【方法】基于不同氮肥处理的田间试验数据,建立了水稻冠层NDVI与植株吸氮量之间的定量关系,并利用独立试验数据进行了检验,筛选出最佳的氮素光谱诊断模型。在此基础上,结合水稻高产栽培经验,对早稻的追肥用量进行了实时推荐,并和当地农户施肥模式及氮肥-产量曲线计算出的最佳氮肥用量和产量进行对比。【结果】水稻关键生育时期(苗期、分蘖期、拔节期、抽穗期和灌浆期)的冠层NDVI与水稻植株吸氮量都呈显著正相关,相关性高于整个生育期,指数函数拟合效果要优于线性函数。独立试验检验结果表明,单生育时期的预测效果高于整个生育期,指数模型优于线性模型;其中,分蘖期和拔节期的光谱诊断模型表现最佳,预测精度分别为0.907和0.941。推荐施肥应用表明,与常规农户施肥模式相比,光谱诊断施肥模式在产量不减少的情况下降低了氮肥用量,提高了氮素利用率,而产量与常规施肥没有显著差异。在低密度和高密度处理下,光谱推荐施肥模式的施氮量与最佳施氮量的误差分别为2.12%、-2.22%;而产量与最高产量的误差分别为-0.75%、-5.04%。【结论】光谱推荐施肥模式可在保证产量的情况下,降低氮肥用量,提高氮肥农学利用率,在水稻生产中有较好的推广利用价值。     

地力水平和种植密度对冬小麦子粒产量和氮素利用率的影响

[目的]旨在探讨不同地力水平下冬小麦子粒产量和氮素利用率对种植密度的响应并分析子粒产量和氮素利用率协同提高的途径,为制定冬小麦高产高效栽培管理措施奠定理论基础。[方法]试验在高、低两个地力条件下进行,以大穗型冬小麦品种泰农18为试验材料,设置135万、270万和405万株/hm23个种植密度,研究地力水平和种植密度对子粒产量及构成、氮素吸收效率、氮素利用效率和氮素利用率等相关指标的影响。[结果]高地力水平下子粒产量高于低地力水平,但氮素利用效率和氮素利用率均较低。各地力水平下,提高种植密度可显著提高冬小麦穗数和子粒产量,提高成熟期地上部氮素积累量和氮素吸收效率,但氮素收获指数和氮素利用效率随种植密度上升呈下降趋势,增密对子粒含氮量无显著影响。各地力水平下增密后氮素吸收效率增加的幅度远高于氮素利用效率降低的幅度,所以氮素利用率随着种植密度的提高而呈上升趋势。低地力水平下增密后子粒产量和氮素利用率提高的幅度均高于高地力地块。[结论]在高、低地力水平下,增加种植密度均可提高子粒产量和氮素利用率,有利于实现冬小麦的高产高效栽培,且低地力水平下增密后子粒产量和氮素利用率的增幅高于高地力水平。     

Review grain yield and nitrogen use efficiency in rice production regions in China

As one of the staple food crops, rice(Oryza sativa L.) is widely cultivated across China, which plays a critical role in guaranteeing national food security. Most previous studies on grain yield or/and nitrogen use efficiency(NUE) of rice in China often involved site-specific field experiments, or small regions with insufficient data, which limited the representation for the current rice production regions. In this study, a database covering a wide range of climate conditions, soil types and field managements across China, was developed to estimate rice grain yield and NUE in various rice production regions in China and to evaluate the relationships between N rates and grain yield, NUE. According to the database for rice, the values of grain yield, plant N accumulation, N harvest index(HIN), indigenous N supply(INS), internal N efficiency(IE_N), reciprocal internal N efficiency(RIE_N), agronomic N use efficiency(AE_N), partial N factor productivity(PEPN), physiological N efficiency(PE_N), and recover efficiency of applied N(RE_N) averaged 7.69 t ha~(–1), 152 kg ha~(–1), 0.64 kg kg~(–1), 94.1 kg kg~(–1), 53.9 kg kg~(–1), 1.98 kg kg~(–1), 12.6 kg kg~(–1), 48.6 kg kg~(–1), 33.8 kg kg~(–1), and 39.3%, respectively. However, the corresponding values all varied tremendously with large variation. Rice planting regions and N rates had significant influence on grain yield, N uptake and NUE values. Considering all observations, N rates of 200 to 250 kg ha~(–1) commonly achieved higher rice grain yield compared to less than 200 kg N ha~(–1) and more than 250 kg N ha~(–1) at most rice planting regions. At N rates of 200 to 250 kg ha~(–1), significant positive linear relationships were observed between rice grain yield and AE_N, PE_N, RE_N, IE_N, and PFPN, and 46.49, 24.64, 7.94, 17.84, and 88.24% of the variation in AE_N, PE_N, RE_N, IE_N, and PFPN could be explained by grain yield, respectively. In conclusion, in a reasonable range of N application, an increase in grain yield can be achieved accompanying by an acceptable NUE.     

不同冬小麦品种产量和氮素吸收利用效率差异

【目的】研究新疆南疆不同冬小麦品种产量、氮素吸收利用效率的差异及对氮肥的响应,为小麦氮高效育种、氮高效品种选择及氮肥优化施用提供参考依据。【方法】设置3个施氮量,选择新疆南疆种植12个品种（系）为材料,研究不同氮肥水平下不同小麦品种的产量、氮素积累量、氮素利用率、氮素吸收效率和氮素利用效率等指标差异。【结果】随着施氮量的增加不同品种收获穗数、穗粒数增加,千粒重降低,氮素积累量和产量增加;氮素利用率、氮素吸收效率和氮素利用效率随着施氮量的增加而降低。氮素利用率较高品种为新冬40号,新冬60号,15/6317。氮高效品种达到高氮效率的途径不同,在不施氮（N_o）条件下新冬40号,新冬60号,15/6317氮素利用率高主要是氮素吸收效率和氮素利用效率的共同作用,以氮素利用效率为主;在施氮条件下新冬60号和新冬40号在氮素吸收效率高来自其较高氮素吸收能力,而15/6317氮素利用率较高是氮素吸收效率和氮素利用效率的共同作用。【结论】不同品种达到氮高效的途径不同,针对不同小麦品种的氮素吸收和利用特性进行调控,提高小麦氮素吸收和利用效率。     

不同类型冬小麦氮、硫积累分配及利用效率的差异

【目的】揭示不同类型冬小麦氮、硫积累、分配与利用规律及对氮、硫肥反应的差异。【方法】在田间条件下,连续3年先后选用13个高产品种,采用聚类分析方法进行冬小麦氮、硫利用效率类型的划分,并在0—20cm土层土壤水解氮含量92.2mg·kg-1、有效硫含量42.4mg·kg-1的地力条件下,研究不同类型冬小麦在不同氮、硫施用量下,氮素和硫素含量、积累量、收获指数、籽粒产量的差异及其与氮素利用效率和硫素利用效率的关系。【结果】结果表明,冬小麦的氮素利用效率与硫素利用效率呈极显著正相关关系,依据品种间氮素利用效率和硫素利用效率的差异,将供试品种划分为氮低效硫低效组、氮中效硫中效组和氮高效硫高效组。氮低效硫低效组小麦品种植株含氮量和含硫量一般高于氮中效硫中效组和氮高效硫高效组品种,氮素收获指数和硫素收获指数则小于氮中效硫中效组和氮高效硫高效组品种。在24kg·hm-2施氮水平下施硫,氮高效硫高效组和氮中效硫中效组品种植株含氮量显著提高,氮素积累量、硫素积累量和产量显著增加;氮低效硫低效组品种与氮高效硫高效组和氮中效硫中效组品种相比,施硫处理氮素积累量的增加量较小,而氮素收获指数降低的幅度较大,产量显著降低。在240kg·hm-2施氮水平下施硫,氮高效硫高效组品种植株含氮量和含硫量仍显著提高,氮素和硫素积累量显著增加,但氮素和硫素收获指数及产量无显著变化,氮硫利用效率显著降低;氮中效硫中效组和氮低效硫低效组品种氮素和硫素积累量无显著变化,多数品种的氮素和硫素收获指数亦无显著变化,产量和氮硫利用效率降低。【结论】冬小麦产量形成需硫量的相对高低与需氮量一致,氮素利用效率与硫素利用效率可以协同提高。在保持植株一定氮素和硫素积累量的基础上,通过提高氮素和硫素收获指数促进籽粒产量的增加,是实现冬小麦对氮素和硫素高效利用的一个重要途径。     

dep1 improves rice grain yield and nitrogen use efficiency simultaneously by enhancing nitrogen and dry matter translocation

The rice cultivars carrying dep1(dense and erect panicle 1) have the potential to achieve both high grain yield and high nitrogen use efficiency(NUE). However, few studies have focused on the agronomic and physiological performance of those cultivars associated with high yield and high NUE under field conditions. Therefore, we evaluated the yield performance and NUE of two near-isogenic lines(NILs) carrying DEP1(NIL-DEP1) and dep1-1(NIL-dep1) genes under the Nanjing 6 background at 0 and 120 kg ...     

Grain yield and nitrogen use efficiency of an ultrashort-duration variety grown under different nitrogen and seeding rates in direct-seeded and double-season rice in Central China

Nitrogen(N) and seeding rates are important factors affecting grain yield and N use efficiency(NUE) in directseeded rice. However, these factors have not been adequately investigated on direct-seeded and double-season rice(DDR) in Central China. The objective of this study was to evaluate the effects of various N and seeding rates on the grain yield and NUE of an ultrashort-duration variety grown under DDR. Field experiments were conducted in 2018 in Wuxue County and 2019 in Qichun County, Hubei...     

氮肥滴施次数及比例对机采棉产量和氮肥利用率的影响

【目的】 研究氮肥随水滴施次数和分配比例对机采棉生长、产量以及氮肥利用率的影响。【方法】 2017~2018两年田间试验,设置5个处理:(1)不施氮肥(CK),(2)施肥8次+前轻后重(习惯施肥,N8-B),(3)施肥8次+前重后轻(N8-F),(4)施肥10次+前轻后重(N10-B),(5)施肥10次+前重后轻(N10-F)。【结果】 增加氮肥施用次数显著提高棉花干物质重和氮素吸收量。在相同氮肥滴施次数下,氮肥分配“前重后轻”处理(F)棉花干物质重和氮素吸收量均显著高于“前轻后重”处理(B)。2017和2018年,施肥10次处理棉花产量较施肥8次处理分别增加17.9%和34.7%,棉花氮肥利用率分别提高了24.02和28.61个百分点。N8-F和N10-F处理棉花产量较相同施肥次数的N8-B和N10-B处理分别增加7.0%~11.1%和12.1%~21.5%,氮肥利用率分别提高了12.0~26.5和11.2~24.9个百分点。【结论】 增加氮肥滴施次数及前期施用比例可促进滴灌机采棉生长和氮素吸收,提高机采棉产量和氮肥利用率。     

黑龙江省几个玉米杂交种氮效率差异的分析

本试验利用对氮素反应呈不同表现类型的6个玉米杂交种，在4个施氮水平下，对其氮效率、产量及相关性状等进行了研究。结果表明，不同玉米杂交种的产量、氮累积量、氮效率和氮响应度存在明显的差异。克单8和垦玉6的氮响应度较高，增施氮肥可较大幅度提高产量。据不同施氮量下的玉米氮效率，可将小米杂交种划分为四种氮效率类型：绥玉7属于双高效型、龙单13属于低氮高效型、垦玉6属于高氮高效型、垦鉴玉6属于双低效犁。通径分析表明，氮吸收效率和氮利用效率对氮效率的作用均是直接作用大于间接作用，氮吸收效率对氮效率的直接作用在3个施氮处理中均大于氮效率对氮效率的直接作用，且是低氮下吸收作用强，高氮下利用效率对氮效率的直接作用要增强。据性状与产量相关分析表明，低氮条件下应选择抽丝期穗位叶叶绿素含量高，抽丝期穗位叶叶面积大，籽粒氮含量高，氮效率高和氮收获指数高的品种；高氮条件下应选择抽丝期生物量大和成熟期生物量大的品种。     

施肥水平对不同氮效率水稻氮素利用特征及产量的影响

【目的】研究不同施肥水平下不同氮效率杂交水稻产量差异与氮素吸收和利用的关系,以期为水稻品种改良和高产高效栽培技术提供依据。【方法】以氮高效品种(德香4103)和氮低效品种(宜香3724)为材料,通过设置低肥(75 kg N·hm~(-2),37.5 kg P_2O_5·hm~(-2),75 kg K_2O·hm~(-2),记为N_1P_1K_1)、中肥(150 kg N·hm~(-2),75 kg P_2O_5·hm~(-2),150 kg K_2O·hm~(-2),记为N_2P_2K_2)、高肥(225 kg N·hm~(-2),112.5 kg P_2O_5·hm~(-2),225 kg K_2O·hm~(-2),记为N_3P_3K_3)3种施肥水平,并在各施肥水平下均增设一不施氮处理,研究其对不同氮效率水稻产量和氮素利用效率的影响及其结实期氮素吸收、转运和分配特性。【结果】品种与施肥水平对杂交稻主要生育时期及各生育阶段氮素的累积、转运、分配,以及氮素利用特征和产量均存在显著影响;品种对氮肥回收利用率、千粒重,以及总颖花数的影响均不同程度的高于施肥水平的调控效应;施肥水平对主要生育时期及各生育阶段氮素的累积,结实期叶片和茎鞘氮的运转,以及产量调控作用显著。N_2P_2K_2相对于N_1P_1K_1处理能促进不同氮效率水稻主要生育时期及各生育阶段氮素的累积,提高氮收获指数,促进结实期叶片和茎鞘中氮素的运转,进而显著提高稻谷产量及氮肥利用效率,且N_2P_2K_2均显著高于同品种下其他的肥料施用处理,为本试验最佳的氮磷钾肥施用模式;N_3P_3K_3处理易造成结实期叶片及茎鞘中氮滞留量增加,氮转运贡献率显著降低,导致产量及氮肥利用效率显著降低。氮高效品种具有总颖花数、结实率高的特征,其主要生育时期氮素累积量,氮素干物质生产效率,氮素稻谷生产效率及氮素收获指数等均显著高于氮低效品种,但千粒重并不是氮高效品种所独有的特征;此外,氮高效品种结实期更有利于叶片与茎鞘氮素的运转及穗部氮素的累积,尤其氮高效品种具有较高的茎鞘氮素转运率,其与氮肥生理利用率、回收利用率及农艺利用率均存在显著正相关性(r=0.699*—0.743*),是导致不同氮效率品种氮肥利用效率、产量差异的重要因子,可作为氮效率及品种鉴选的评价指标,也可以以进一步提高抽穗至成熟期氮高效水稻品种茎鞘氮素运转率,作为实现水稻高产与氮高效利用协调统一的另一重要途径。【结论】本试验条件下,氮高效品种具备的结实期茎鞘高氮素转运、高总颖花数及结实率是优于氮低效品种而形成产量差异的主要因素,N_2P_2K2_为氮高效品种配套的最优氮磷钾肥施用模式。提高抽穗期至成熟期氮累积量,促进叶片与茎鞘氮运转量,尤其应提高茎鞘氮素运转率,可实现高产与氮高效利用的同步提高。     

新型包膜控释尿素对水稻产量与氮肥利用率的影响

以晚粳稻‘秀水128’为供试水稻品种,在田间条件下,对金正大新型硫磺加树脂双层包膜控释尿素(SPCU)和树脂包膜控释尿素(PCU)对水稻产量及氮肥利用率的影响作了研究。结果表明：(1)与普通尿素 PU 70%(147 kg/hm² N)处理相比,等氮量一次性基施 SPCU 70%处理产量为 8 022.5 kg/hm²,显著提高 5.26%;氮肥利用率为 49.32%,显著提高 38.42%;(2)与普通尿素 PU 100%(210 kg/hm² N)相比,一次性基施 SPCU 70%处理产量无显著差异;氮肥利用率显著提高 33.69%;(3)相同施氮量下,SPCU产量与PCU无显著差异,但 SPCU比 PCU氮肥利用率显著增加。     

Postponed and reduced basal nitrogen application improves nitrogen use efficiency and plant growth of winter wheat

Excessive nitrogen(N) fertilization with a high basal N ratio in wheat can result in lower N use efficiency(NUE) and has led to environmental problems in the Yangtze River Basin, China. However, wheat requires less N fertilizer at seedling growth stage, and its basal N fertilizer utilization efficiency is relatively low; therefore, reducing the N application rate at the seedling stage and postponing the N fertilization period may be effective for reducing N application and increasing wheat yield and NUE. A 4-year field experiment was conducted with two cultivars under four N rates(240 kg N ha–1(N240), 180 kg N ha–1(N180), 150 kg N ha–1(N150), and 0 kg N ha–1(N0)) and three basal N application stages(seeding(L0), fourleaf stage(L4), and six-leaf stage(L6)) to investigate the effects of reducing the basal N application rate and postponing the basal N fertilization period on grain yield, NUE, and N balance in a soil-wheat system. There was no significant difference in grain yield between the N180 L4 and N240 L0(control) treatments, and the maximum N recovery efficiency and N agronomy efficiency were observed in the N180 L4 treatment. Grain yield and NUE were the highest in the L4 treatment. The leaf area index, flag leaf photosynthesis rate, flag leaf nitrate reductase and glutamine synthase activities, dry matter accumulation, and N uptake post-jointing under N180 L4 did not differ significantly from those under N240 L0. Reduced N application decreased the inorganic N content in the 0–60-cm soil layer, and the inorganic N content of the L6 treatment was higher than those of the L0 and L4 treatments at the same N level. Surplus N was low under the reduced N rates and delayed basal N application treatments. Therefore, postponing and reducing basal N fertilization could maintain a high yield and improve NUE by improving the photosynthetic production capacity, promoting N uptake and assimilation, and reducing surplus N in soil-wheat systems.     

氮高效利用基因型大麦氮素转移及氮形态组分特征

【目的】揭示氮高效利用基因型大麦生育后期氮素分配转运的生理机制,为大麦高效氮肥管理和高产栽培提供理论依据。【方法】采用土培盆栽试验,利用前期筛选出的氮高效利用基因型大麦（DH61、DH121+）和低效利用基因型大麦（DH80）为试验材料,分析其在不施氮、低氮（125 mgN·kg^-1土）、正常氮（250 mgN·kg^-1土）和高氮（375 mgN·kg^-1土）4个氮素处理下籽粒产量、生物量及生育后期地上部营养体氮素转移特性和植株氮形态组分构成特征。【结果】（1）随施氮量的减少,不同氮效率基因型大麦籽粒产量和地上部生物量均减少。同一施氮处理,高效基因型大麦籽粒产量和地上部生物量高于低效基因型。不施氮处理下,高效型大麦DH61和DH121+籽粒产量分别是低效型DH80的1.96、2.03倍;低氮处理下分别是低效型DH80的2.10、2.37倍。扬花期和灌浆期,不施氮和低氮处理下两类基因型大麦植株氮浓度无明显差异,氮高效基因型大麦干物质形成能力较强。（2）高效基因型大麦植株能够积累较多的氮素,扬花前高效基因型氮素积累量占大麦生育期氮积累量的比例高于低效基因型。低氮（125 mgN·kg^-1土）、正常氮（250 mgN·kg^-1土）、高氮处理（375 mgN·kg^-1土）下,高效基因花前氮素积累量是低效基因型的1.31、1.38、1.49倍,充足的氮素积累为后期灌浆结实奠定了物质基础。（3）随着氮素用量的增加,氮素转运量呈单峰曲线变化,氮素转移率和氮素转运量对籽粒的贡献率则逐渐下降,过高的氮肥施用不利于氮素向籽粒的转运。高效基因型DH61和DH121+籽粒氮素来源更多依赖于前期地上部营养体的氮素转移,不施氮和低氮氮素转运量对籽粒的贡献率分别为35.06%、40.06%和76.37%、81.72%。而低效基因型DH80籽粒的氮素来源则以后期根系氮素的吸收和转移为主,氮素吸收量对籽粒的贡献率为68.20%和34.84%。（4）相同氮素处理下,扬花至灌浆期大麦茎秆和叶片中营养性氮含量增加,功能性氮含量变化平稳,而结构性氮含量则降低;籽粒营养性氮含量逐渐增加,结构性氮含量缓慢下降。且较低效基因型,高效基因型大麦茎秆和叶片结构性氮含量的降低幅度大,氮素转运能力强。低氮处理下,高效基因型扬花期至灌浆期茎秆和叶片结构性氮含量分别降低49.57%、62.58%;灌浆至成熟期分别降低64.47%、28.11%。【结论】氮高效利用基因型大麦籽粒氮含量受花后茎秆和叶片中结构性氮的分解转化决定,营养器官中结构性氮的再利用有利于氮素利用效率的提高。     

稳定氮肥用量和施用方式对水稻产量和氮肥效率的影响

通过田间小区试验,研究了稳定氮肥用量及施用方式对水稻产量、氮素累积量、氮肥利用效率、经济效益及土壤养分含量的影响。结果表明,与不施稳定氮肥相比,100%稳定氮肥一次施用、100%稳定氮肥分次施用、85%稳定氮肥一次施用和70%稳定氮肥一次施用分别增产53.1%、61.6%、39.7%和36.7%,植株地上部氮素总累积量分别增加64.0%、80.9%、36.0%和32.3%,经济效益分别增加50.4%、59.5%、37.4%和34.5%。与农民习惯等氮施肥相比,稳定氮肥一次施用和分次施用分别增产5.7%和11.6%,植株地上部氮素总累积量分别增加9.9%和21.2%,经济效益分别增加5.8%和12.2%。等氮施用稳定氮肥较农民习惯施肥促进水稻对氮素的吸收累积,提高了产量,分次施用达到显著性差异。稳定氮肥一次施用和分次施用氮肥表观利用率和农学效率高于农民习惯施氮,且分次施用达到显著性差异,生理效率和偏生产力3处理无显著性差异。施用稳定氮肥能够提高土壤碱解氮含量,且随着施用量增加而增大。稳定氮肥施氮量在240 kg N·hm^-2且基肥与分蘖肥6:4分次施用时,能较好地协调水稻高产与稳定氮肥合理利用的统一。     

Grain yield,nitrogen use efficiency and physiological performance of indica/japonica hybrid rice in response to various nitrogen rates

Utilizing the heterosis of indica/japonica hybrid rice (IJHR) is an effective way to further increase rice grain yield.Rational application of nitrogen (N) fertilizer plays a very important role in using the heterosis of IJHR to achieve its great yield potential.However,the responses of the grain yield and N utilization of IJHR to N application rates and the underlying physiological mechanism remain elusive.The purpose of this study was to clarify these issues.Three rice cultivars currently used...     

覆膜时期和施氮量对陇东旱塬玉米产量和水氮利用效率的影响

[目的]以抗逆性强的紧凑型玉米品种先玉335为供试作物,研究施氮量、覆膜时期及其互作对陇东旱塬玉米生理指标、产量性状及水氮利用效率的影响,以期为陇东旱塬区玉米高产高效栽培提供理论依据.[方法]2012年11月至2019年11月,连续设置覆膜时期(春季覆膜和秋季覆膜)和施纯N量(0、75、150、225、300、375、...     

Differences of yield and nitrogen use efficiency under different applications of slow release fertilizer in spring maize

Excessive or insufficient application of fertilizer has raised broader concerns regarding soil and environmental degradation. One-time application of slow release fertilizer (SF) has been widely used to reduce yield gap with potential maize yield and improve nitrogen use efficiency (NUE). A 2-year field experiment (2018–2019) was conducted to evaluate the effects of SF rates from 0 to 405 kg N ha^–1 (named F0, SF225, SF270, SF315, SF360, and SF405) and 405 kg N ha^–1 of common fertilizer (CF405) on the grain yield, biomass and N accumulation, enzymatic activities related with carbon–nitrogen metabolism, NUE and economic analysis. Results indicated that the highest grain yields, NUEs and economic returns were achieved at SF360 in both varieties. The enzymatic activities related with carbon–nitrogen metabolism, pre- and post-silking accumulation of biomass and N increased with increasing SF rate, and they were the highest at SF360 and SF405. The grain yield at SF360 had no significant difference with that at SF405. However, the N partial factor productivity, N agronomic efficiency and N recovery efficiency at SF360 were 9.8, 6.6 and 8.9% higher than that at SF405. The results also indicated that the average grain yields, NUE and economic benefit at SF405 were 5.2, 12.3 and 18.1% higher than that at CF405. In conclusion, decreasing N rate from 405 kg ha^–1 (CF) to 360 kg ha^–1 (SF) could effectively reduce the yield gap between realized and potential maize yields. The N decreased by 11.1%, but the yield, NUE and economic benefit increased by 3.2, 22.2 and 17.5%, which created a simple, efficient and business-friendly system for spring maize production in Jiangsu Province, China.