华北区部分主栽玉米杂交种的氮效率分析

玉米生产中氮肥的过量施用,不但导致氮肥利用率下降,生产成本提高,而且还会造成地下水污染,因而越来越受到人们的重视.选用氮高效作物品种是解决这些问题的重要途径.本试验利用华北地区主栽的8个杂交种在高、低氮条件下研究了产量、吸氮量、氮效率及其生理基础.两年结果表明,不同玉米杂交种的产量、氮效率和不同生育期吸氮量都存在显著的基因型差异.农大108高、低氮条件下都有较高产量,且吸氮量高,成熟期茎秆氮残留多.中单2996在两个氮水平和两种土壤条件下,吸氮量相对较高,茎秆残留少,氮转移率较高.通径分析表明,吸收效率对     

膜下滴灌春玉米氮素吸收规律与增产效应

研究春玉米膜下滴灌条件下氮肥对玉米氮素吸收、干物质积累以及氮肥的增产作用,提出试验条件下的最佳施氮量.结果表明,增加施氮量能够增加膜下滴灌春玉米地上部干物质积累及氮素吸收能力,过量施氮导致干物质及氮素累积降低;玉米产量随着施氮量增加而增加,300 kg/hm²时达到最高产量,此时氮肥农学效率、氮肥利用率以及生理利用率均达到最大.采用二次曲线拟合,计算最佳施氮量为291.80 kg/hm²,此时最高产量为14 964.54 kg/hm².     

氮肥后移对晚收夏玉米产量及氮素吸收利用的影响

采用田间试验研究氮肥后移对晚收夏玉米产量、氮素吸收分配和氮肥利用效率的影响。结果表明,氮肥后移使夏玉米产量和氮素积累量增加,在农民习惯收获和晚收条件下分别较正常施氮增产2.11%～2.91%和7.23%～9.52%。晚收较农民习惯收获增产2.12%～6.42%,氮积累量增加1.10%～3.18%;晚收夏玉米茎和子粒氮积累量增加,而叶和其他器官中积累量减少。氮肥后移提高了夏玉米氮肥利用率和农学效率,晚收条件下氮肥利用率提高了3.52%～6.87%,氮肥农学效率提高了0.82～1.60 kg/kg。氮肥按"30%苗肥+30%大喇叭口肥+40%吐丝肥"方式施用在晚收条件下产量和氮肥利用效率最高。     

秸秆还田与施氮肥对松嫩平原玉米氮素吸收及产量的影响

针对松嫩平原玉米生产特点,设置玉米秸秆不还田、秸秆还田两种条件和3个施氮水平,研究秸秆还田与施氮肥对松嫩平原玉米氮素吸收及产量的影响。结果表明,除收获期玉米植株氮素含量变化规律不明显外,其余时期玉米植株氮素含量、干物质量、氮积累量及产量均随氮肥用量的增加而增加。在玉米3叶期,供试的3个施氮水平下,秸秆还田处理均使玉米氮素含量和吸收积累量降低,至拔节期秸秆还田处理对玉米植株氮素含量的不利影响消失。在不施氮肥条件下,秸秆还田处理提高了拔节期玉米植株氮素的含量;玉米的氮素吸收积累量在不施氮肥条件下仍低于秸秆不还田处理。在玉米收获期,秸秆还田处理增加了玉米子粒的氮素含量与氮素吸收积累量。在3个施氮水平下,秸秆还田处理玉米产量与秸秆不还田处理差异不显著。     

水氮互作对膜下滴灌玉米产量及水氮利用的影响

通过田间裂区试验,研究不同灌水量和施氮量对膜下滴灌玉米生理生长、产量及其构成因素和水、氮利用的影响。结果表明,水氮互作对玉米产量影响差异显著(P0.05)。玉米单株叶面积随着施氮量与灌水量的增加而增大。随着灌水量的增加,玉米耗水量呈上升趋势,玉米水分利用效率呈下降趋势。氮肥农学效率及氮肥偏生产力随着施氮量的增加而减小。当灌水量大于2 700 m~3/hm~2、施氮量大于200 kg/hm~2时,玉米干物质积累和产量不在增加,产量呈下降趋势。在本试验条件下,推荐最佳灌水量为2700 m~3/hm~2,施氮量为200 kg/hm~2。     

氮肥对半干旱区膜下滴灌玉米叶片叶绿素荧光特性及产量的影响

针对吉林省西部半干旱区的生态特点,研究氮素营养水平对膜下滴灌条件玉米净光合速率、叶绿素荧光参数、光合酶活性和产量的影响。结果表明,适宜的氮肥施用量可显著提高叶片光合性能,随着氮肥施用量的逐渐增加,叶片气体交换参数也逐渐升高;当氮肥超过300 kg/hm2时,各项指标开始下降。在荧光诱导动力学参数中,最大光化学效率(Fv/Fm)对种植模式的改变比较敏感,膜下滴灌下各处理平均Fv/Fm均显著高于同期普通生产田对照,随着施氮量的增加Fv/Fm增加;高氮处理穗位叶Fv/Fm无显著差异。施用氮肥均增加了玉米穗位叶PEP和Ru BP羧化酶活性。在膜下滴灌模式下,玉米达到最高产量时的氮肥施用量为200 kg/hm2,与300 kg/hm2时的产量无显著差异;非膜下滴灌玉米获得最高产量时的施氮量为300 kg/hm2。     

不同施氮方式对夏玉米产量、氮素吸收与利用的影响

大田条件下以不施氮处理为对照(CK),设置农民传统施肥(FP)、水肥一体化(WF)以及水肥一体化减氮20%(WF-N)4种水氮管理模式,研究氮肥用量及施氮方式对玉米产量形成、氮素吸收及其利用效率的影响。结果表明,同等施氮量下,与FP处理相比,WF处理的子粒产量、穗粒数、千粒重和完熟期植株干物质积累量分别增加9.57%、7.45%、2.41%和9.14%;完熟期植株氮素积累量增加8.77%,氮肥偏生产力(PFPN)、氮肥农学效率(AEN)、氮肥利用率(NUE)分别增加9.57%、45.28%、28.65%。减氮20%条件下,水肥一体化施氮处理的玉米产量及产量构成、完熟期植株干物质积累量与FP处理间无显著差异,其PFPN、AEN、NUE较FP处理分别增加24.34%、21.87%和21.38%。     

玉米秸秆还田与实地氮肥管理对水稻产量与米质的影响

 以中熟粳稻扬粳4038为材料,在大田试验条件下研究了玉米秸秆还田与实地氮肥管理对水稻产量和稻米品质的影响。三年（2009—2011）试验结果表明: 1）玉米秸秆还田能提高稻田土壤全氮和有机质含量; 2）在不施氮条件下,玉米秸秆还田处理较对照产量提高了18.9%~32.0%; 3）在实地氮肥管理模式下,玉米秸秆还田处理较对照施氮量下降了7.4%~16.7%,但产量提高了0.5%~11.0%,氮肥偏生产力提高了18.0%~31.7%; 4）在不施氮或实地氮肥管理条件下,玉米秸秆还田均较对照显著提高了整精米率、最高黏度和崩解值,降低了垩白粒率、垩白度、最终黏度和消减值;玉米秸秆还田对水稻的出糙率、精米率、直链淀粉含量和胶稠度无显著影响。在不施氮条件下,与对照相比,玉米秸秆还田提高了籽粒中蛋白质含量。上述结果表明,玉米秸秆还田有利于培肥土壤,采用实地氮肥管理将有助于进一步降低水稻施氮量,提高产量和改善米质。     

氮高效玉米基因型氮素生产效率研究

通过田间试验,在高氮和低氮条件下对不同氮效率的27个玉米自交系氮素生产效率进行研究。结果表明,高氮和低氮下,高产氮高效型自交系在吐丝期氮素干物质生产效率最高,分别为53.69、58.69 g/g,高产氮高效型自交系在吐丝期干物质量高于低产氮低效型自交系。施氮肥后氮素子粒生产效率和氮素干物质生产效率均有下降趋势。高氮和低氮下高产氮高效型自交系在生育后期植株氮积累量高于低产氮低效型自交系,低氮下二者差异显著,高产氮高效型自交系比低产氮低效型自交系高5.88%,氮积累量的差异主要来自于吐丝后氮的积累。高产氮高效型植株生育后期根系吸收能力强,子粒氮素利用效率高,施氮肥后高产氮高效型植株生育后期氮吸收积累能力增强。     

部分春性和半冬性小麦品种氮效率差异分析

为了解小麦冬春性与氮素利用的关系,在大田条件下,以江苏省主栽的15个小麦品种为材料,比较了半冬性和春性小麦的氮效率差异。结果表明,相同施氮条件下,半冬性小麦的平均氮肥吸收效率(NUEa)和氮肥生产效率(NGPE)分别比春性小麦高12.19%和9.64%,差异均达显著水平。其中,NUEa和NGPE最高的半冬性小麦品种均为济麦22,春性小麦两个指标最高的品种均为扬麦15。半冬性小麦的平均氮肥表观利用率(NUR)、氮肥农学效率(NAE)、氮素生理效率(NPE)及氮收获指数亦高于春性小麦,但差异均不显著。半冬性或春性类型小麦中各指标都存在氮高效和氮低效的品种,且品种间差异均极显著;不同品种氮效率高或低的机制不同,使得对氮肥的吸收、利用、转运的能力存在差异,生产中应根据不同品种氮效率机制特点采用不同的施肥应对策略。     

不同基因型玉米氮素吸收利用效率研究进展

玉米氮效率的评价方法与指标不尽一致,导致对玉米基因型不同的分类结果。玉米氮效率研究主要集中于根系对氮素的吸收、叶片对氮素的还原同化、氮素在植株体内的积累和分配以及地上部生长势与氮效率的关系方面。以子粒为主要收获对象的玉米,穗、子粒发育状况对玉米产量起着关键作用,有关穗、子粒发育对玉米氮效率贡献率的大小、不同氮效率基因型玉米穗、子粒发育的差异以及内在生理生化机制研究较少。对不同氮效率基因型玉米子粒发育与氮效率之间关系、子粒发育尤其是顶部子粒的早期发育(决定穗粒数的形成)对氮素的反应、氮高效品种顶部子粒的早期发育是否优于氮低效型、氮素对不同氮效率基因型玉米子粒发育的影响机制等问题有待进一步研究。     

不同玉米自交系氮效率的分析

试验在4个氮处理水平上对8个玉米自交系的氮效率进行了研究。结果表明,玉米自交系在产量、生物量和氮累积量上存在显著的差异。据氮效率分析,黄C属低氮、高氮处理下产量均较高的双高效型,340属低氮高效型自交系,00冬属高氮高效型自交系,C8605属低氮、高氮处理下产量均较低的双低效型自交系。通径分析表明,在3个施氮处理中氮吸收效率对氮效率的作用均大于氮利用效率对氮效率的作用,且低氮下吸收效率对氮效率的作用大,高氮下利用效率对氮效率的作用大。     

不同氮肥模式对夏玉米产量、蛋白质品质和氮素利用特性的影响

以高产玉米品种郑单958和先玉335为供试材料,在大田生产条件下设置4个施氮水平,研究不同氮肥模式对两个高产玉米品种子粒产量、蛋白质产量及氮素利用特性的影响。结果表明,两个玉米品种子粒产量随施氮量的增加显著增加,均以240 kg/hm~2处理最高,先玉335子粒产量显著高于郑单958;两个玉米品种子粒蛋白质含量及其产量随施氮量的增加显著增加,先玉335的蛋白质含量及其产量均高于郑单958;两个玉米品种氮素利用效率、氮肥生产效率和氮肥农学利用效率随施氮量的增加而显著降低,均以180 kg/hm2处理最高,先玉335的氮素利用效率、氮肥生产效率和氮肥农学利用效率均高于郑单958。综合分析认为,两个玉米品种均以240 kg/hm~2处理可以同步协调实现较高的子粒产量、蛋白质含量和氮素利用效率,获得产量、品质和高氮素利用效率的协调统一。     

A comprehensive study of plant density consequences on nitrogen uptake dynamics of maize plants from vegetative to reproductive stages

Nitrogen (N) use efficiency (NUE), defined as grain produced per unit of fertilizer N applied, is difficult to predict for specific maize (Zea mays L.) genotypes and environments because of possible significant interactions between different management practices (e.g., plant density and N fertilization rate or timing). The main research objective of this study was to utilize a quantitative framework to better understand the physiological mechanisms that govern N dynamics in maize plants at varying plant densities and N rates. Paired near-isogenic hybrids [i.e., with/without transgenic corn rootworm (Diabrotica sp.) resistance] were grown at two locations to investigate the individual and interacting effects of plant density (low—54,000; medium—79,000; and high—104,000 pl ha⁻¹) and sidedress N fertilization rate (low—0; medium—165; and high—330 kg N ha⁻¹) on maize NUE and associated physiological responses. Total aboveground biomass (per unit area basis) was fractionated and both dry matter and N uptake were measured at four developmental stages (V14, R1, R3 and R6). Both plant density and N rate affected growth parameters and grain yield in this study, but hybrid effects were negligible. As expected, total aboveground biomass and N content were highly correlated at the V14 stage. However, biomass gain was not the only factor driving vegetative N uptake, for although N-fertilized maize exhibited higher shoot N concentrations than N-unfertilized maize, the former and latter had similar total aboveground biomass at V14. At the R1 stage, both plant density and N rate strongly impacted the ratio of total aboveground N content to green leaf area index (LAI), with the ratio declining with increases in plant density and decreases in N rate. Higher plant densities substantially increased pre-silking N uptake, but had relatively minor impact on post-silking N uptake for hybrids at both locations. Treatment differences for grain yield were more strongly associated with differences in R6 total biomass than in harvest index (HI) (for which values never exceeded 0.54). Total aboveground biomass accumulated between R1 and R6 rose with increasing plant density and N rate, a phenomenon that was positively associated with greater crop growth rate (CGR) and nitrogen uptake rate (NUR) during the critical period bracketing silking. Average NUE was similar at both locations. Higher plant densities increased NUE for both medium and high N rates, but only when plant density positively influenced both the N recovery efficiency (NRE) and N internal efficiency (NIE) of maize plants. Thus plant density-driven increases in N uptake by shoot and/or ear components were not enough, by themselves, to increase NUE.     

Application of Molecular Markers in Breeding for Nitrogen Use Efficiency

Summary

Nitrogen use efficiency (NUE) is defined as dry matter yield produced per unit of N supplied and available in the soil. NUE is approximately 33% for cereal production worldwide. Increased cereal NUE must accompany increased yield needed to feed the growing world population. Consequently, continued efforts are needed to include plant selection under low N input which is not often considered a priority by plant breeders. Molecular markers have accelerated plant breeding in a number of areas including biotic (disease and insect) resistance and abiotic (drought, low nitrogen fertilization and frost) tolerance. Marker-based technology has already provided scientists with a powerful approach for identifying and mapping quantitative trait loci (QTL) and would lead to the development of a better understanding of genetic phenomena. Two main NUE studies have been discussed. The first study identified QTL for NUE in maize involved the grain yield and secondary morphological traits of interest, such as plant height, ear leaf area, ears per plant and kernels per ear. This was compared with second study of QTL for yield and its components with genes encoding cytolistic gult-amine synthestase and leaf N0₃ ^- content. These secondary traits were correlated with yield and demonstrated segregation with high heritability under low nitrogen conditions. Marker assisted selection (MAS) should be able to offer significant advantages in cases where phenotypic screening is particularly expensive or difficult, including breeding projects involving multiple genes, recessive genes, late expression of the trait of interest, seasonal considerations, or geographical considerations. In addition to reducing costs of conventional breeding, MAS also has the potential to generate time savings. Possibly, the greatest contribution of QTL mapping to plant breeding will be the basic understanding of the genetic architecture of quantitative traits, thereby relating specific genetic loci with the biological mechanisms associated with desirable phenotypes.     

玉米秸秆还田条件下冬灌时间与施氮方式对冬小麦生长发育及水肥利用效率的影响

为给玉米秸秆还田条件下冬小麦的水氮运筹提供依据,以小麦品种临优2069为材料,研究了山西省小麦-玉米一年两熟区玉米秸秆还田条件下冬灌时间和施氮方式对冬小麦生长发育及水氮利用效率的影响。结果表明,随着冬前灌水时间的推迟,小麦总茎数、单株分蘖数、成穗数、产量、籽粒水分生产率、氮肥表观利用率均呈先升高后降低趋势,以11月25日冬灌的最高。在施氮量相同条件下,氮肥一次性底施(N10∶0)的拔节期总茎数、成穗数、产量、籽粒水分生产率和氮素吸收量、表观利用率高于氮肥70%底施+30%拔节期追施(N7∶3)处理,冬前总茎数、单株分蘖数则相反。冬前灌水时间提前和氮肥一次性底施有利于提高小麦前期单株干重;冬前灌水时间推迟和后期追氮则有利于灌浆期穗部和总干物质的积累。因此,山西省小麦-玉米一年两熟区,秸秆还田条件下氮肥采取一次性底施,并于11月25日冬灌,可实现冬小麦的高产高效栽培。     

苗期甘蔗氮高效基因型评价指标的筛选

本研究通过低氮压力选择,筛选出甘蔗氮高效种质,分析影响甘蔗氮高效的重要指标,为甘蔗氮高效育种及栽培提供理论依据。以58份甘蔗种质资源为材料,在苗期采用正常供氮（2 mmol/L N）和低氮（0.2 mmol/L N）处理,分析甘蔗植株形态、干重及氮素在各器官中累积分配的特征。通过主成分分析方法筛选影响甘蔗氮高效利用的重要指标,通过聚类分析对58份种质进行聚类。结果表明,低氮（0.2 mmol/L N）处理可以明显从植物形态区分不同种质的氮利用差异,58份种质低氮条件下的干重范围为0.64~14.75 g/株,氮累积量为5.53~63.00 mg/株,氮利用率范围为115.40~279.30 g/g。对低氮压力下甘蔗干重及氮累积等25个指标进行主成分分析后,提取出4个主要成分,总贡献率为92.35%。通过高、低氮条件下与氮利用效率有关的氮转移系数及基因潜力等19个指标分析后提取出5个主成分,总贡献率为82.21%。影响甘蔗氮高效的重要指标有甘蔗的干重（全株、叶、根）、氮累积量（全株、叶、茎）、氮利用率（全株、叶）、叶的相对氮利用率、茎的基因潜力、茎的相对干物质量和茎的相对氮累积量。经聚类分析后初步将58份甘蔗种质分为氮高效基因型、偏氮高效基因型、偏氮低效基因型和氮低效基因型。     

氮肥运筹对夏玉米氮素利用及土壤无机氮时空变异的影响

研究不同施氮量及基肥追肥比例对土壤无机氮时空分布及玉米氮肥利用效率的影响。结果表明,不同施氮量和基追比显著影响土壤剖面硝态氮含量。各施氮处理不同生育期0～60 cm土层硝态氮含量均显著高于不施氮肥处理,且随施氮量的增加土壤中硝态氮含量增加。夏玉米生长季土壤铵态氮含量较低,且时空变化不明显。玉米氮素农学效率（NAE）、氮素利用效率（NUE）随施氮量的增加显著降低;氮素表观回收率（NRE）有相同的变化趋势,但差异不显著;氮素收获指数（NHI）随施氮量的增加显著增大。相同施氮水平下,“50%基肥+50%大喇叭口肥基追比”的NAE、NUE、NHI和玉米产量显著高于其他处理。因此,在玉米生产中应避免播种时一次性大量施用氮肥,增加后期施氮比例可显著提高氮肥利用效率和玉米产量。     

Effects of sowing date and nitrogen fertilizer on forage yield,nitrogen‐ and water‐use efficiency and nutritive value of an annual triple‐crop complementary forage rotation

Complementary forage rotation (CFR) systems based on non‐limiting inputs of fertilizer nitrogen (N) (～600 kg N ha^?1) are perceived as uneconomic. An experiment was carried out in Australia to investigate the effects of rates and timing of N fertilizer and sowing date on yield, nutrient‐use efficiency and nutritive value of a triple‐crop (maize, forage rape, field peas) CFR system. Treatments were early‐ and late‐sown maize grown with 0 or 135 kg fertilizer N ha^?1 pre‐sowing (N1) and 0, 79 or 158 kg N ha^?1 post‐sowing (N2). Forage rape was sown with 0 or 230 kg N ha^?1 (N3) and field peas without N. Application of fertilizer N at N1, N2 and N3 increased CFR yield from 28·5 to 48·8 t dry matter (DM) ha^?1 and irrigation water‐use efficiency (IWUE) from 3·4 to 6·1 t DM per megalitre. Increase in yield and IWUE of CFR occurs at the expense of nitrogen‐use efficiency (NUE) as applications of N at N1, N2 and N3 decreased NUE of CFR from 524 to 91 kg DM kg^?1 N. Nutritive value, particularly metabolizable energy content of all forages, was similar among N treatments, and interactions between treatments were minimal. Results indicate that increase in NUE of CFR may occur at the expense of reduced yield, but increased IWUE need not compromise the yield of this CFR system.     

Characterizing nitrogen use efficiency in natural and agricultural ecosystems to improve the performance of cereal crops in low-input and organic agricultural systems

Low-input and organic farming systems have notable differences in nitrogen (N) sources, cycling and management strategies compared to conventional systems with high inputs of synthetic N fertilizer. In low-input and organic systems, there is greater reliance on complex rotations including annual and perennial crops, organic N sources, and internal N cycling that more closely mimic natural systems. These differences in farming system practices fundamentally affect N availability and N use efficiency (NUE) and could impact crop traits and breeding strategies required to optimize NUE. We assess genetic and environmental factors that could assist breeders in improving crop performance in low-input and organic farming systems by examining NUE in natural and agricultural ecosystems. Crop plants have often been bred for high N productivity, while plants adapted to low N ecosystems often have lower productivity and higher levels of internal N conservation. Breeders can potentially combine N productivity and N conservation through the use of elite and wild germplasm. Beneficial genetic traits include the ability to maintain photosynthesis and N uptake under N stress and the ability to extract soil N at low concentrations, perhaps through beneficial associations with soil microorganisms. In addition, breeding for specific adaptation to climactic and management practices so that crop uptake patterns match N availability patterns, while minimizing pathways of N loss, will be critical to improving NUE.