内蒙古平原灌区高产春玉米(15 t hm-2以上)产量性能及增产途径

针对内蒙古平原灌区春玉米高产(15 t hm^-2以上)群体产量进一步提高难度大,产量挖潜途径不明确的问题,采用产量构成因素分析与产量性能参数分析相互验证的方法,在4年52点次高产(15 t hm^-2以上)群体产量构成因素分析的基础上,设计不同品种密度试验,研究增密对不同品种群体产量性能的影响,明确不同类型玉米品种的增产途径和栽培调控的主攻方向。结果表明,穗数和穗粒数是决定高产(15 t hm^-2以上)群体产量的主要因素。实现15 t hm^-2以上群体的产量结构为：穗数(7.08~9.60)×10⁴穗,穗粒数477~654粒,千粒重324.7~388.7 g,穗粒重168.9~234.0 g。其合理群体结构衡量指标是LAI_max在6.5以上,平均LAI在5左右,收获期LAI在3.5以上。高秆大穗型品种理想的产量结构是：67 500~75 000穗 hm^-2,每穗610~640粒,千粒重380 g左右,单穗粒重220~240 g,产量大于15 t hm^-2;株高适中的中小穗型品种,理想产量结构是： 75 000~97 500穗 hm^-2,每穗520~600粒,千粒重340~355 g,单穗粒重180~220 g,产量在16.5 t hm^-2以上。密度增加促进平均作物生长率(MCGR)和单位面积总籽粒数(TGN)的增加进而提高产量,但增密后平均净同化率(MNAR)降低导致穗粒数显著降低并限制了TGN的提高潜力。通过增密为主的结构性挖潜,使得群体功能的增益大于个体生产性能的降低,实现高产(15 t hm^-2以上),属于“得失性补偿增产”;在优化群体结构的基础上,提高个体生产能力,突破个体库容降低的限制,进行功能性挖潜,实现群体结构和个体功能协同增益的“差异性补偿增产”,是产量进一步提高的重要途径。     

作物耐热生理基础与基因发掘研究进展

热胁迫是农作物生产中的环境限制因子,影响作物生长发育并导致农作物减产与降低农产品品质。作物耐热性生理生化、基因发掘与分子机制研究将为农业生产与耐热新品种培育奠定基础。综述了热胁迫逆境对作物营养生长阶段和生殖生长阶段的影响,重点阐述了开花期与子粒灌浆期等作物产量形成关键时期受热害时作物的生理与发育,介绍了作物主要的4种热响应方式,即膜流动性改变、蛋白质解折叠、细胞骨架解聚和代谢物变化,总结了Hsf热激转录因子的调控与耐热分子机制,并展望了应用生物技术创制作物耐热新种质与遗传改良的可行性。本文为作物耐热性生理基础、基因发掘、分子机制与育种途径等研究提供参考。     

宁夏引黄灌区玉米高产挖潜群体特征分析

为了探明宁夏玉米高产群体特征以及限制高产的因子。以‘郑单958’和‘先玉335’为供试品种,在密度为121215株/hm~2和110205株/hm~2下对产量及产量构成、关键生育时期的群体光合性能、干物质动态变化等特征进行研究。结果表明:群体叶面积指数(LAI)随生育进程呈单峰曲线变化,吐丝前后达到最大值;光合有效辐射量沿冠层垂直向下呈大幅下降,以120~180 cm处(棒三叶位置)透光率的变化最为明显;整个生育期群体干物质积累动态呈S形曲线,成熟期干物质积累最大;2种不同高产挖潜模式均可获得高产;但‘先玉335’挖潜模式群体结构更为理想,后期氮肥供应不足是产量限制因子。因此认为,‘先玉335’在原密度下,后期通过增施N肥,来增加千粒重和穗粒数,是宁夏进一步提高玉米产量的重要途径。     

棉花新品种秋乐5号产量构成因子分析及高产途径

应用秋乐5号区试和生产试验数据．对其产量构成各因子与皮棉产量进行变异性、遗传相关与通径分析，结果表明：总铃数对皮棉产量的贡献最大，其次是单铃重和子指．衣分最小。因此，在大面积推广中实现秋乐5号高产的途径是：提高有效铃数，适当增加铃重，保持子指和衣分的稳定适中，促进各因子间协调发展。     

水肥调控下作物产量构成因子的研究进展

水和肥是影响作物产量与品质的关键因子,水肥的相互作用对作物生长起着制约与促进的作用,叶片面积是作物生长和产量构成的主要生理指标,其叶面积指数可直接反映出作物的生长状况,叶面积指数大小直接与产量密切相关。本文在查阅了水肥调控措施对作物生长特性和产量的影响以及叶面积指数与产量的关系等大量国内外有关文献的基础上,针对作物产量的形成机理,对水肥调控下作物主要生理指标与产量间相互关系的研究现状和进展进行了归纳总结,探讨仍需研究的重点问题,为作物高产和水肥高效利用提供理论支撑。     

黔西北山区小麦产量构成因素及高产育种途径研究

采用多元回归、多元相关分析法，分析了黔西北山区小麦产量构成因素，结果表明，在三要素中，决定产量的主导因子是穗数，其次是千粒重，最后是穗粒数，在此基础上提出了本区小麦高产育种应走大穗较多穗型求高产的育种途径，为本区小麦产量进一步提高提供了理论指导。     

国审新麦18号丰产稳产性及其产量结构分析

通过对新麦18号国家、河南省中间试验结果分别进行多年多点联合方差分析、作物品种区域试验统计分析系统程序分析,采用DPS统计分析方法,通过不同产量水平下产量构成因素的动态结构分析,以及产量构成因素的通径分析,结果表明：新麦18号丰产性突出,稳产性好,适应性强;500～550 kg/667 m2产量水平时,产量三因素变异系数均较大,但是,通过各种途径均容易达到高产;550～700kg/667 m^2产量水平时,产量三因素变异系数较小,产量三因素对产量的效应依次为千粒重＞穗数＞穗粒数.新麦18号的高产栽培技术途径是：在保证有足够穗数的基础上,主攻千粒重是夺高产的关键.     

作物产量“三合结构”定量表达及高产分析

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。     

玉米弱势粒库特征及其调控机理研究进展

密植条件下玉米弱势粒败育和灌浆受限是玉米产量挖潜的重要限制因子。系统总结了作物弱势粒库特征及其相关生理过程研究进展,探讨了玉米弱势粒败育启动因子、弱势粒灌浆障碍与库容量和库活性关系、弱势粒库特征与激素和多胺水平的关系及外源调控途径,提出了玉米密植群体弱势粒库特征及其主控生理基础研究中存在的问题和思路,为明确玉米密植群体弱势粒库特征及其调控途径提供参考。     

大豆种植密度对玉米/大豆间作系统产量形成的竞争效应分析

旱区作物间作系统是优化作物群体质量、提高产量的一种重要种植方式,从产量构成因子角度探讨作物间作竞争优势机制还鲜见报道。本研究设置3个大豆密度梯度和4个种植比例(玉米与大豆以2∶0、0∶2、2∶2和2∶4间作),分析间作系统的作物竞争指数、产量构成和最终产量的差异性变化,探讨间作群体产量增加的作物竞争机制。结果表明,不同大豆密度和种植比例组合下的间作系统产量提高14%～23%。玉米的实际产量损失大于0,大豆的实际产量损失小于0。间作系统中玉米的穗重、穗长、穗粗、穗粒重、轴重和千粒重均显著高于单作;除结荚长度和主茎节间长度外,间作系统中大豆的单株粒重、单株荚数、单株总粒数、单株有效粒数、主茎节数和百粒重低于单作或与单作间无显著差异。间作系统中玉米的竞争比率大于1,大豆的竞争比率小于1,在3种大豆密度下玉米和大豆的竞争比率分别为2.08、1.84、1.68和0.49、0.56、0.63,表明随着大豆密度的增加,间作中玉米的竞争比率增加的同时大豆的竞争比率降低。玉米的侵占力大于0,大豆的侵占力小于0。玉米产量与轴重、千粒重、穗重、穗粒重、穗长、行粒数呈正相关关系,与秃尖长呈负相关关系。通径分析表明,直接作用中,穗粒重对玉米产量的贡献最大(2.18);间接作用中,轴重、千粒重通过每穗粒重对玉米产量的贡献较大(1.64和1.58)。综上所述,大豆间作玉米有间作优势,间作优势来源于每穗粒重。     

中国粮食增产潜力影响因素分析

为了分析中国粮食增产潜力的影响因素,预测粮食增产潜力,本研究通过对粮食增产潜力影响因素的相关理论分析和数据定量分析可以得出,依靠增加耕地面积提高粮食产量的难度相对较大,提高粮食单产更能提升粮食增产潜力。粮食播种面积的影响因素包括复种指数、土地复垦率等,影响粮食单产的因素主要包括中低产田改造、水资源合理运用、施用化肥、机械化生产、自然灾害、产后损失、物流损失等。最后得出粮食增产因素具有较大程度的提升空间,粮食增产具有较大潜力。     

‘Fingerprints’ of four crop models as affected by soil input data aggregation

The spatial variability of soil properties is an important driver of yield variability at both field and regional scale. Thus, when using crop growth simulation models, the choice of spatial resolution of soil input data might be key in order to accurately reproduce observed yield variability. In this study we used four crop models (SIMPLACE<LINTUL-SLIM>, DSSAT-CSM, EPIC and DAISY) differing in the detail of modeling above-ground biomass and yield as well as of modeling soil water dynamics, water uptake and drought effects on plants to simulate winter wheat in two (agro-climatologically and geo-morphologically) contrasting regions of the federal state of North-Rhine-Westphalia (Germany) for the period from 1995 to 2008. Three spatial resolutions of soil input data were taken into consideration, corresponding to the following map scales: 1:50 000, 1:300 000 and 1:1 000 000. The four crop models were run for water-limited production conditions and model results were evaluated in the form of frequency distributions, depicted by bean-plots.In both regions, soil data aggregation had very small influence on the shape and range of frequency distributions of simulated yield and simulated total growing season evapotranspiration for all models. Further analysis revealed that the small influence of spatial resolution of soil input data might be related to: (a) the high precipitation amount in the region which partly masked differences in soil characteristics for water holding capacity, (b) the loss of variability in hydraulic soil properties due to the methods applied to calculate water retention properties of the used soil profiles, and (c) the method of soil data aggregation.No characteristic “fingerprint” between sites, years and resolutions could be found for any of the models. Our results support earlier recommendation to evaluate model results on the basis of frequency distributions since these offer quick and better insight into the distribution of simulation results as compared to summary statistics only. Finally, our results support conclusions from other studies about the usefulness of considering a multi-model approach to quantify the uncertainty in simulated yields introduced by the crop growth simulation approach when exploring the effects of scaling for regional yield impact assessments.     

Estimating the environmental footprint of barley with improved nitrogen uptake efficiency—a Swedish scenario study

Plant breeding is a powerful tool for improving nitrogen (N) uptake efficiency and thus reducing the environmental impact relating to crop production. This study evaluated the environmental impact of current barley production systems in two Swedish agricultural areas (South and East) compared with scenarios with improved N uptake efficiency at two levels, in which the fraction of mineral N available for daily crop uptake was increased by 50 and 100%. Life cycle assessment (LCA) methodology was used to quantify energy use, global warming potential (GWP) and acidification and eutrophication potentials along the production chain for spring barley with differing N uptake efficiency, but similar N application rate. The functional unit, to which all energy use and emissions were related, was 1 Mg barley grain. Energy use, GWP and acidification proved to be higher for the East production system, mainly due to lower yield, while eutrophication was higher for South. The two impacts most affected by improved N uptake efficiency were eutrophication and GWP, with GWP decreasing due to a combination of higher yield, soil carbon sequestration and lower indirect emissions of N₂O due to lower N leaching. Accounting for land savings due to increased yield, reducing the pressure to transform land elsewhere, would further lower the carbon footprint. Potential eutrophication per Mg grain was reduced by 15% in the production system with the highest N uptake efficiency in southern Sweden. Crops with improved N uptake efficiency can thus be an important complementary measure for reducing N losses to water, provided that the N application rate does not increase. However, incentives for farmers to maintain or even lower the N application rate might be required. Using simulation modelling is a promising approach for assessment of expected effects of improved crop varieties when no long-term experimental data are available. However, advanced crop models are required to better reflect the effect of plant breeding on e.g. expected yield. Future model development should involve expertise in plant breeding, plant physiology and dynamic crop and soil modelling.     

Identifying plant architectural traits associated with yield under intercropping: Implications of genotype-cropping system interactions

Increased yields of some crops have resulted from indirect selection of plant architectural traits related to yield. This study examines the potential relationship between plant architecture and yield for a legume grown under intercropping, Field experiments were conducted in 1991 to examine the response of two cowpea (Vigna unguiculata (L.) Walp.) genotypes with contrasting plant habits to sole crop and intercrop with pearl millet (Pennisetum americanum (L.) Leeke), and to identify cowpea traits associated with yield under intercropping. The cultivur with a bush-type habit was higher-yielding in sole crop, whereas the cultivar with a spreading habit was higher-yielding in intercrop. For F₂ cowpea populations, pod number was most highly correlated with seed yield in intercrop. The number of branches and nodes, particularly in areas with increased access to light, and increased internode length were also important in intercrop. Selection for improved yield in sole crop may not necessarily lead to improved yield in intercrop, and different plant traits may be more appropriate for cultivars intended for use in inter-crop than for those intended for use in sole crop.     

Compensation-Induced Yield Gains in Mixtures of Common Bean (Phaseolus vulgaris L.)

Over the course of two planting seasons field trials were conducted at the CIAT farm in Palmira (Colombia). The experiments included nine tropical bean lines grown in pure stands and seven mixtures obtained by combining these lines on the basis of equal proportions in seed number.
In the case of several pure lines, inferior seed quality led to low germination and uneven population densities, especially in the first planting season. Analogously, missing plants also occurred with the corresponding mixtures. A significant and positive relationship between mixing induced yield gains and patchiness in mixtures was found, indicating that intergenotypic compensation was a major determinant for mixture effects on yield. In common bean as a tropical subsistence crop seed quality is known to be erratic. It is concluded that compensation effects in mixtures of common bean may be expected to be of practical importance regarding the improvement of yield stability over seasons.     

Stickstoffdüngung und chemischer Pflanzenschutz in einem Dauerfeldversuch und die Ertragsgesetze von Liebig, L.iebscher, WOLLNY und MITSCHERLICH

Nitrogen fertilization and chemical plant protection in a long-term field experiment and the yield response laws of L iebig , L iebscher , W ollny and M itscherlich
An interpretation of L iebig 's "law of the minimum", L iebscher 's and W ollny 's "law of the optimum" and M itscherlich 's "law of constant activity" for two growth factors is presented. With three-quadrant diagrams (crop yield vs. N fertilization, crop yield vs. N uptake, N uptake vs. N fertilization) a long-term field experiment in Göttingen (Ackerbau-Systemversuch) is analyzed. This experiment started 1981 with the following treatments: 1. crop rotation (a: short rotation, sugar-beet, winter-wheat, winter-barley/vetch-green-manure; b: long rotation, sugar-beet, winter-wheat, winter-barley, lucerne, maize, faba beans); 2. chemical plant protection (a: with; b: without); 3. mineral nitrogen fertilization procedure (a: N-fixed, cumulative effects; b: N-rotating, one year's effects of different N fertilization); 4. mineral nitrogen fertilization (a: nil; b: suboptimal; c: optimal; d: hyper-optimal doses).
Without chemical plant protection resource use efficiency of applied nitrogen decreased according to L iebscher 's and W ollny 's "law of the optimum". In most cases this "law of the optimum" was applicable to the empirical data. L iebig 's "law of the minimum" and M itscherlich 's "law of constant activity" are exceptional cases, whereas L iebscher 's and W ollny 's "law of the optimum" has more general validity. For maximal resource use efficiency the growth factors have to be combined in optimal amounts.     

Rice Yield Gap due to Iron Toxicity in West Africa

Iron toxicity is a widespread nutrient disorder in lowland rice, notably in West Africa. It occurs in irrigated or rain-fed rice crops when the soil contains excessive amounts of iron. Associated with leaf discoloration symptoms (bronzing), this excessive iron uptake causes poor growth and tillering and leads to severe yield reductions. Field experiments were carried out in West Africa from 1994 to 1998 at two sites with high iron toxicity and one non-toxic site to assess the effects of iron toxicity on rice cropping and evaluate the tolerance of promising rice cultivars available in West Africa. To estimate yield losses caused by iron toxicity, the yield potential was simulated using the ORYZA-S rice growth and yield model. Based on the potential yield, the yield loss in an iron-toxic site is the combination of the yield gap caused by unknown site factors and the yield gap caused by iron toxicity. Compared to the referential yield obtained in a non-iron-toxic site, iron toxicity reduced rice yields by 16–78 % (mean 43 %). The extent of the yield loss depended on rice cultivar, iron toxicity intensity and crop management strategy (water control and mineral fertilisation). A strong correlation obtained between yield and the iron toxicity score, based on visual symptoms indicated an approx. 400 kg ha⁻¹ yield loss for each visual score point increase. The high genetic variability in iron toxicity tolerance and close correlation between leaf symptom score and grain yield between rice genotypes provide a good basis for breeding varieties that can produce higher yields under iron-toxic conditions.     

作物高光效之管见

光合作用提供了作物产量形成的物质基础。目前作物的叶面积指数和经济系数已难以继续增加,若想进一步提高作物产量就必须提高生物量,提高作物光能利用率成为关键。作物高光效是一个内涵和外延非常广的概念,涉及作物生命活动的全过程,与众多学科相联系,不同学科有着不同的理解。作者根据现有的研究进展,结合从事作物生理、育种和栽培的实践,从光合作用的主要过程及关键调控位点、作物光能利用率、高光效作物的生理基础与形态特征和高光效作物的筛选与鉴定对"作物高光效"进行了概述,以期为今后的作物"高光效"研究提供一点有益的思考与借鉴。