Drought Effect on Grain Number and Grain Weight at Spike and Spikelet Level in Six‐Row Spring Barley

Water is the primary regulator of yield formation in cereals. The effect of water limitation and its timing on development of yield components were studied in detail at spike and spikelet level in spring barley (Hordeum vulgare L.). An experiment with three watering treatments (control watering, CONT; drought prior to pollination, DR1 and terminal drought, DR2) was set up in a large greenhouse (20 × 30 m). In addition to watering treatments, two NPK fertilizer application rates (0 and 120 kg N ha^?1) were used to investigate the fertilizer effect. The drought effect exceeded the effect of fertilizer application for grain number and single grain weight (SGW). DR1 reduced the number of grains, whereas DR2 reduced both SGW and the number of grains. Resuming the watering at pollination (DR1) restored photosynthesis and enhanced grain filling, resulting in almost similar SGW in DR1 and CONT plants. Spikelets in the upper mid‐section of the spike dominated yield formation in all treatments. This was particularly emphasised in DR1 plants as 58 % of the grain yield was produced in spikelets 3–5, whereas in DR2 and CONT plants it was 39 % and 36 %, respectively. Hence, drought prior pollination strongly reduced yielding capacity (=grain number) in apical and basal spikelets. DR1 and DR2 reduced substantially grain yield and grain N yield resulting in low nitrogen use efficiency.     

Temperature Effects on the Duration of the Spikelet Growth Phase and Spikelet Abortion in Barley

Above optimal temperatures in cereals, when measured in thermal time units (°Cd) can lead to underprediction of developmental events by models, particularly when cereals are sown late in Mediterranean-type environments or grown under subtropical conditions. Our objective was to assess the effects of high temperatures on the length of the spikelet growth phase, the number of spikelet nodes per spike and level of spikelet abortion in spring barley (Hordeum vulgare L.). The spikelet growth phase (from the end of the spikelet initiation phase to anthesis) of three cultivars, 'Bandulla', 'Schooner' and 'Weeah' was subjected to two temperature regimes. In the first of two sowings, the mean daily maximum temperature for one regime was 24 °C (maintained for 6 h daily) and the mean daily minimum was 8 °C (24/8 °C). The second temperature regime was 27/17 °C. Corresponding temperatures for the second sowing, which was subjected to slightly longer photoperiods, were 26/8 °C and 26/17°C, respectively. The duration of the spikelet growth phase was longer for 27/17 °C than for 24/8 °C in the first sowing when measured in calendar time (d). In the second sowing, the duration of the spikelet growth phase was slightly shorter under the higher temperature regime (d). The duration of the spikelet growth phase (in°Cd) was greatly increased by the higher temperature treatment in both sowings. In the first sowing, the percentage of aborted spikelets was greater at HT than at LT for Bandulla and Weeah at both sowing times and the duration of the spikelet growth phase increased with higher night temperatures, suggesting that length of the spikelet growth phase was not the sole factor responsible for the proportion of aborted spikelets.     

氮素养分对青稞营养功能特征及籽粒产量的影响

为确定在不同氮素条件下影响青稞生产力的关键性营养功能特征,以‘藏青2000’为试材,就不同施氮水平对青稞营养功能特征及籽粒产量的影响进行试验研究。结果表明：施氮显著提高了青稞籽粒产量、株高、相对生长率和比叶面积,而降低了单位叶面积根量和叶干物质含量,施氮水平与株高、相对生长率和比叶面积呈正相关关系,与单位叶面积根量和叶干物质含量呈负相关关系。随着施氮强度加大,产量持续提高,但增长速率下降,青稞籽粒产量与施氮水平呈二次曲线关系(y=-171.25x ²+1327.3x+10, R ²=0.958, P小于0.05)。青稞籽粒产量与株高(y=43.026x-2596.6, R ²=0.8994, P小于0.05)、相对生长率(y=7178.7x-150.66, R ²=0.5361, P小于0.05)和比叶面积(y=6.4604x+413.3, R ²=0.4153, P小于0.05)呈显著线性正相关,与叶干物质含量(y=-29.668x+4045.7, R ²=0.4488, P小于0.05)呈线性负相关关系,与单位叶面积根量(y=-2025.4x+2746.4, R ²=0.0579, P大于0.05)无明显相关性。结果表明：青稞的植株高度、相对生长率和比叶面积促进产量增长,叶干物质含量对产量有抑制作用,而单位叶面积根量对产量影响不明显。在本试验条件下,植株高度、相对生长率、比叶面积和叶干物质含量4个功能特征可在物种水平上被认为是影响青稞生产力的标记性特征。     

牛粪生物质炭基肥对青稞生长、产量及氮素利用的影响

为探讨不同配比的生物质炭基肥料对青稞生长、产量和氮素利用的影响。以牛粪为研究对象,在限氧条件下经高温热解炭化制成生物炭,将生物质炭与一定比例的化学肥料混合,制成生物质炭基肥料。研究表明,随着碳化的进行,牛粪中的全氮和有机质（有机碳）含量降低,材料的碳氮比也随之降低,而全磷、全钾的含量升高;增施牛粪生物炭,青稞叶片中叶绿素含量升高,促进作物对肥料中养分的利用,进而利于青稞生长,草木灰与化肥配施的叶片叶绿素含量最高;不同处理籽粒产量之间的差异达到极显著;化肥施入量减少至70%,牛粪生物炭施入量30%时,籽粒产量最高,达到4830.75 kg/hm²,高于有机肥、草木灰与化肥配施和羊粪的处理（较对照增产13.88%）;22500 kg/hm²羊粪处理的秸秆产量最高;同等氮输入条件下,减少化肥施用量,增加生物炭,可以提高氮素利用效率。     

施肥对春青稞干物质积累、分配及产量的影响

为研究施肥对青稞干物质积累、分配及产量的调节作用,以‘藏青27’、‘QTB13’和‘QTB25’为试验材料,比较分析不同施肥处理下干物质积累、分配及产量的变化规律。结果表明：增加施肥量促进青稞分蘖期—成熟期的干物质积累及开花期和成熟期干物质向营养器官和籽粒的分配,提高了花前营养器官贮藏同化物转运量及对籽粒贡献率,降低了花后同化物输入籽粒量对籽粒贡献率。‘QTB13’和‘QTB25’在F₂条件下,更有利于干物质积累及向营养器官和穗部的分配,花后同化物输入籽粒量最大,产量也最大。‘藏青27’在F₃条件下,更有利于干物质积累及向营养器官和穗部的分配,花后同化物输入籽粒量和对籽粒贡献率最大,产量也最大。说明合理施肥有利于青稞干物质积累分配及产量提高。     

施氮水平对啤酒大麦植株氮素吸收与利用及籽粒蛋白质积累和产量的影响

2004—2006年连续两个生长季,以苏啤3和单2两个啤酒大麦品种为材料,探讨施纯氮0、75、150、225和300 kg hm^-2条件下,啤酒大麦氮素积累和转运、氮素利用及籽粒产量和蛋白质积累的特性。在0~225 kg hm^-2施氮量范围内,啤酒大麦花前植株氮素积累量和转运量均随施氮水平的提高呈上升趋势,但施氮量提高至300 kg hm^-2后,提高幅度变小;而花前氮素转运效率及其对籽粒氮的贡献率则均随施氮水平提高呈单峰曲线变化。籽粒谷氨酰胺合成酶和谷-丙转氨酶活性也随着施氮水平的提高而上升,促进蛋白质积累,提高籽粒蛋白质含量,而当施氮量低于197 kg hm^-2时籽粒蛋白质含量才低于12%,符合啤酒大麦酿造要求。经回归分析,在施氮量为241 kg hm^-2时产量最高。此外,氮肥回收效率以225 kg hm^-2施氮处理为最高,氮素生理利用效率和氮收获指数随施氮量增加而显著降低。综合考虑各项指标,建议在类似本试验条件的啤酒大麦生产区,施氮量以150~197 kg hm^-2为宜。     

双季稻区长期不同施肥管理对大麦干物质积累及产量的影响

为探明双季稻区不同施肥制度对大麦干物质积累及产量的影响, 以 ‘通 0306’ 和 ‘蒙啤麦 1号’ 为材料, 采用田间小区试验方法, 系统比较研究了 30%有机肥+70%化肥、 60%有机肥+40%化肥和无肥 3种施肥制度对大麦干物质积累及产量的影响。结果表明, 大麦主要生育期, 单株根系、 茎干物质和地上部分干重均表现为 60%有机肥＞30%有机肥＞无肥; 分蘖期至成熟期, 各处理间大麦单株根系和茎干重差异均达显著水平。叶、 穗均表现为 60%有机肥＞30%有机肥＞无肥, 60%有机肥和 30%有机肥处理均显著高于对照。分蘖期到成熟期, 根系干重占总干物质量的比例为无肥＞30%有机肥＞60%有机肥, 穗干重比例为 30%有机肥＞60%有机肥＞无肥; 拔节期到成熟期, 茎的比例均以 60%有机肥处理最高; 叶干物质比例在成熟期为无肥＞60%有机肥＞30%有机肥。大麦主要生育期, 30%有机肥和 60%有机肥处理大麦叶片 SPAD值均显著高于无肥处理; 成熟期, 各处理间差异达显著水平。大麦各生育期, 各处理大麦单株叶面积表现为 60%有机肥＞30%有机肥＞无肥。各施肥处理大麦产量表现为 60%有机肥＞30%有机肥＞无肥, 分别比无肥增产 717.45~721.15 kg/hm²和 756.45~782.05 kg/hm²。说明不同施肥制度大麦干物质积累和产量有各自特征, 有机肥与化肥配施处理植株干物质总量大而且分配合理, 有利于改善产量构成因素, 增加大麦产量。     

氮肥运筹对江淮麦区饲料大麦籽粒产量与品质的影响

为给江淮麦区饲料大麦生产氮肥合理施用提供参考,于2012－2014年连续2年以盐丰1号和扬饲麦1号2个饲料大麦品种为试验材料,研究了不同氮肥用量与运筹比例对大麦籽粒产量与品质的影响。结果表明,氮肥用量增加使2个品种的产量随之增加,施氮量从A1（90 kg／hm2）增至A2（210 kg／hm2）时,盐丰1号、扬饲麦1号平均产量分别增加16．4％,31．6％,施氮量从A2增至A3（330 kg／hm2）时,处理间产量差异不显著;相同施氮量不同运筹比例对2个品种产量影响不明显;对于籽粒品质,施氮量从A1增至A2时,盐丰1号与扬饲麦1号籽粒蛋白质含量增幅分别为8．6％～10．2％和8．8％～10．8％,施氮量从A2增至A3时,籽粒蛋白质含量也有增加,但未达显著水平;施氮量的增加使2个品种籽粒淀粉含量略有下降,但降幅不明显;相同施氮量不同运筹比例对2个品种籽粒品质影响不显著。氮肥处理下产量与农艺性状相关分析表明,用氮肥来调控大麦产量可能主要是通过调控穗粒数与穗数来实现增产。综合考虑,建议在江淮麦区生产上大麦氮肥施用方案为,总施氮量为210 kg／hm2,氮肥运筹比例为基肥∶拔节肥∶穗肥以5∶2∶3或6∶2∶2为宜。     

氮肥施用量对不同紫甘薯品种产量和氮素效率的影响

选取紫甘薯品种浙紫1号、宁紫2号和紫菁2号,设置3个施氮处理,即0 (N0)、75 (N1)和150 (N2) kg hm^–2纯氮,于2013-2014年2个生长季在青岛农业大学现代农业科技示范园进行大田试验,研究不同氮肥用量对块根产量、干物质累积速率、氮素累积量及氮素效率的影响。结果表明,施用氮肥不同程度地降低了浙紫1号和紫菁2号的薯块产量,其中,浙紫1号的N1、N2处理分别较N0处理降低12.64%和13.32%,紫菁2号分别降低3.94%和29.06%;宁紫2号N1处理产量略高于N0处理,两年分别较N0处理提高8.5%和3.4%,而N2处理块根产量显著低于N0处理。茎蔓生物量和氮素累积量随着施氮量的增加而增加,而收获指数、氮素收获指数和氮素利用效率逐渐降低。第1年N1、N2处理的茎蔓干物质累积量分别较N0处理提高2.7%~20%和12.3%~36.4%,第2年分别提高12.6%~51.9%和28.7%~85.5%。相关分析表明,块根产量与氮素效率各指标均呈显著或极显著正相关;而茎蔓生物量与收获指数、氮素收获指数及氮肥利用效率均呈极显著负相关(r = –0.615^**, –0.704^**, –0.663^**)。肥沃土壤上施用氮肥会造成浙紫1号和紫菁2号的茎蔓旺长,光合产物向薯块转运比例降低,导致源库比例不协调,块根产量下降。宁紫2号对氮肥的需求相对较高,施用氮肥75 kg hm^–2时鲜薯产量提高,而施氮量过高时薯块产量降低。因此,紫甘薯在含氮量较高的肥沃土壤上种植时,对氮肥的需求量较低,茎蔓和薯块的协调生长是提高块根产量和氮素利用效率的保障。     

秸秆还田配施化学氮肥对冬小麦氮效率和产量的影响

2006—2007年生长季, 通过田间定位试验, 研究了秸秆还田配施化学氮肥对冬小麦产量干物质积累、氮效率和产量的影响。结果表明, 与单施氮肥相比, 秸秆还田配施氮肥的冬小麦全生育期干物质积累总量较高, 干物质积累量及其占全生育期干物质积累量的百分比抽穗前阶段较低, 而抽穗到成熟阶段则较高。秸秆还田配施纯氮90、180、270和360 kg hm^-2比单施同量氮肥分别增产7.1%、8.4%、11.1%和10.2%, 其中秸秆还田配施纯氮270 kg hm^-2的产量最高, 显著高于其他各处理。秸秆还田配施氮肥比单施氮肥提高冬小麦的氮效率, 氮肥表观利用率、氮素生产效率和氮肥农学效率分别提高3.3%~9.2%、0.7~4.0和2.7~7.3 kg kg^-1。     

播期和施氮量对冬小麦氮代谢及子粒蛋白质含量的影响

为了阐明播期变化与施氮量对冬小麦氮代谢及蛋白质的影响,采用裂区设计,研究播期和施氮量对冬小麦花后茎叶氮含量、积累量和子粒蛋白质含量的影响。结果表明,适度晚播可以提高冬小麦茎、叶的氮含量、氮素积累量和子粒蛋白质含量。与不施氮肥相比,施用氮肥可以显著增加冬小麦不同生育时期地上部氮素累积量,且随着施氮量的提高,茎、叶的氮积累量也表现为先升高后降低的趋势。在同一播期条件下,子粒蛋白质含量以施氮150和225kg/hm ²的处理最高,说明适宜的施氮量能改善子粒品质。分析播期与施氮量对子粒蛋白质含量的作用程度可知,施氮量是引起冬小麦子粒蛋白质含量变化的主要因素,作用程度占66.85%。在本试验条件下,兼顾冬小麦花后茎叶氮素代谢及产量,实现高子粒蛋白质含量的推荐播期是10月11日,施氮量为150kg/hm ²。研究结果可为山西省冬小麦调优栽培提供理论和技术支持。     

Effects of Fungicide on Grain Yield of Barley Grown in Different Cropping Systems

The effect of fungicides and their combination on yield of barley under different nitrogen, slurry and tillage treatments was investigated at Hohenschulen Experimental Station near Kiel, Germany in 1991–97. Various fungicide treatments (no fungicide, and treatment with stem, leaf and ear fungicides and combinations of these), two nitrogen levels (120 and 240 kg N ha⁻¹), two tillage systems (minimum and conventional tillage) and four slurry applications (no application, and autumn, spring and autumn plus spring applications) were used. On average, fungicide application increased barley yield by 1.1 t ha⁻¹. The fungicide treatments could be classified into four types: (1) fungicides against stem diseases, which slightly increased yield by 0.25 t ha⁻¹, very similar to the results for the untreated control; (2) leaf fungicides and ear fungicides applied separately, and fungicides against a combination of stem and leaf diseases, which increased yield by 1.0 t ha⁻¹ on average; (3) fungicides against a combination of ear and stem diseases, which increased the yield by 1.22 t ha⁻¹, and (4) fungicides against a combination of leaf and ear diseases and a combination of stem, leaf and ear diseases, which increased yield by 1.59 t ha⁻¹ on average. The effects of fungicide on the yield were modified by crop husbandry. It can be concluded that application of fungicides against a combination of leaf and ear diseases could increase barley yield and reduce yield variation.     

每穴苗数和施氮量对双季机插稻产量及氮肥利用效率的影响

以常规早稻品种中嘉早17和杂交晚稻品种五优308为材料,针对双季机插稻生产中存在的前期发不起、中期控不住、后期穗小苗弱影响双季机插稻产量及氮肥利用效率的问题,通过大田试验研究施氮量和每穴苗数对双季机插稻产量及氮肥利用效率的影响。结果表明,氮肥用量和每穴苗数对双季机插稻产量及氮肥利用效率有显著影响。机插早晚稻均以中氮高苗组合（早稻N12D5,晚稻N13D4）产量最高,早稻为8.12t/hm ²,晚稻为9.62t/hm ²,但与低氮高苗组合(早稻N10D5,晚稻N11D4)产量差异不显著。氮肥吸收利用率早晚稻均随施氮量的增加呈先上升后下降的趋势,随每穴苗数的增加而升高。其中早稻氮素吸收利用率以N10D5处理最高,晚稻虽以N13D4处理最高,但与N11D4处理间差异不显著。干物质积累量所表现出的趋势基本和产量一致。在不影响产量的前提下,适当增加单株苗数,可使早稻比当前习惯施氮量减少16.7%,晚稻可减少15.4%。早稻氮素利用率提高10.66%,晚稻提升1.99%。由此可见,合理地增加每穴苗数和降低施氮量既可以获得足够的单位面积有效穗数实现高产,又可以提高氮素利用效率。     

施肥量和穴内插秧密度对寒地粳稻产量和品质性状的影响

以中熟超高产粳稻品种龙稻5号、晚熟超高产粳稻品种松粳9号和优质晚熟品种五优稻1号为试验材料,研究了施肥量和穴内插秧密度对寒地粳稻产量和品质的影响。结果表明,施氮量的增加可以提高高产品种的产量,但导致了优质品种贪青晚熟,降低了优质品种的产量;施氮量的增加可以显著提高蛋白质含量、糙米率和精米率,但也显著降低了稻米的直链淀粉含量和味度值。穴内插秧密度对产量的影响表现为先增加后降低趋势,对稻米品质的影响表现程度不一。施肥量和穴内插秧密度的互作对超高产粳稻品种的产量和品质有影响,对优质品种的蛋白质有影响。从高产和优质的协调考虑,龙稻5号以施纯氮194.90kg/hm²、2棵/穴为宜,松粳9号以施纯氮194.90kg/hm²、4棵/穴为宜,五优稻1号以施纯氮119.94kg/hm²、4棵/穴为宜。     

Influence of Variable Amounts of Irrigation Water and Nitrogen Fertilizer on Growth, Yield and Water Use of Grain Sorghum

Sorghum hybrid CSH-6 was grown in fields in Delhi, India between July–November 1986 in order to study the effect of nitrogen nutrition and irrigation on dry matter accumulation, grain yield and water use. The treatments included 40 Kg Nha⁻¹ combined with two irrigations (30 DAS, 60 DAS), one irrigation (60 DAS) and no irrigation respectively. Rainfall during the crop season was only 17 cm. The unirrigated plants were considerably water stressed and exhibited very low leaf water potential, less leaf area, delayed anthesis, longer crop duration but shorter grain filling duration. The ears showed sterility and yield was only 0.41 t ha⁻¹ without nitrogen fertilization. Addition of nitrogen fertilizer had no significant effect on yield in unirrigated plants. A single irrigation 60 DAS increased yield due to increase in both grain number and grain weight per ear in fertilized and unfertilized crop respectively. Two irrigations in the unfertilized crop increased the yield to 2.2 t ha⁻¹ while similar treatment in the fertilized crop did not increase the yield significantly. Irrigation increased the WUE for grain yield. The results indicate that nitrogen stress and water stress reduced grain yield primarily through grain number rather than grain weight. Irrigation relieved both water stress and nutrient stress. Nitrogen nutrition was not beneficial under severe water stress conditions but was considerably helpful under mild stress. Biomass, grain yield and harvest index show significant correlation with preanthesis water use.     

The Effects of Ethephon, Chlormequat Chloride and Mixtures of Ethephon and Chlormequat Chloride Applied at the Beginning of Stem Elongation on Spike-Bearing Shoots and other Yield Components of Spring Barley (Hordeum vulgare L.)

Effects of chlormequat chloride (CCC), ethephon and mixtures of CCC and ethephon, applied at Zadoks growth stage (ZGS) 30 (the beginning of stem elongation) on the number of spike-bearing shoots and their contribution to grain yields of four spring barley ( Hordeum vulgare L.) cultivars were studied in 1987 and 1988 at McGill University, Quebec, Canada. The results varied between years and among cultivars. The mixtures of CCC and ethephon or ethephon alone, produced significant increases in the number of spikes m⁻² in cultivars Joly and Laurier , in both years, and in Leger only in 1988. Ethephon and ethephon containing mixtures reduced the yields of Joly and Leger in 1988. In both years CCC had no effect on spikes m⁻² for all cultivars. Increases in spikes m⁻² were accompanied by decreases in 1000-grain weight, and/or grains per spike, which offset or more than offset potential benefits from increased spikes m⁻². These results indicate that under continental climatic conditions such as those prevalent in Quebec, Canada, application of PGRs to spring barley at ZGS 30 does not increase grain yield through an increased number of spikes m⁻².     

几个高寒早熟青稞品种在浪卡子县的试种研究初探

为了解几个早熟青稞品种在高寒半农半牧区的生态适应性。以‘浪卡子当地品种’为对照,‘喜拉23’、‘藏青17’、‘藏青690’、‘隆子黑青稞’、‘T28’共6个青稞品种在浪卡子县进行试种,相同的播种和田间管理,对青稞生长情况、产量和品质进行分析。结果表明：（1）6个青稞品种在浪卡子县均能正常成熟,6个品种平均株高60.50~91.09 cm,除‘T28’外其他4个青稞品种株高均高于‘浪卡子当地品种’青稞,其中‘喜拉23’平均株高91.09 cm,较当地品种的68.00 cm高23.09 cm,增高33.96%;（2）秸秆生物量：‘喜拉23’(9239.50 kg/hm²)>‘隆子黑青稞’(7135.75 kg/hm²)>‘藏青17’(6301.33 kg/hm²)>‘藏青690’(5678.00 kg/hm²)>‘T28’(5318.17 kg/hm²)>‘浪卡子当地品种’(4357.67 kg/hm²);（3）籽粒产量：‘藏青17’>‘喜拉23’>‘藏青690’>‘隆子黑青稞’>‘浪卡子当地品种’>‘T28’,‘藏青17’的籽粒产量较‘浪卡子当地品种’增产52.42%,其次为‘喜拉23’籽粒产量较‘浪卡子当地品种’增产50.05%。‘喜拉23’、‘藏青17’、‘隆子黑青稞’能适应浪卡子县的生态环境,且取得较稳定的生物产量和籽粒产量。     

增密减氮对不同类型水稻品种颖花形成的影响

为了明确增密减氮栽培对不同类型水稻品种颖花形成（分化与退化）的影响以及颖花形成与产量的关系,在大田条件下采用裂-裂区试验设计,以籼粳杂交稻（甬优4949）、超级杂交籼稻（扬两优6号）和常规籼稻（黄华占）为供试材料,设置正常氮肥（180kg/hm²）和减氮（90kg/hm²）2个施氮水平,正常密度（30cm×15cm）和增密（20cm×15cm）2个移栽密度处理。结果表明,减氮轻微降低了3个品种的二次枝梗数、颖花分化数和颖花现存数,但差异均不显著;而增密显著降低了颖花分化数和颖花现存数。一次枝梗数、二次枝梗数和幼穗分化期干物质积累对颖花分化数贡献较大。就颖花生产效率而言,增密减氮能有效增加氮素、积温和辐射颖花生产效率,有利于单位面积总颖花数的提高。与扬两优6号和黄华占相比,甬优4949在增密减氮栽培下具有较高的幼穗分化期干物质积累量、颖花生产效率和颖花分化数,从而形成了大的库容,获得了高的产量。     

Yield Responsiveness in Two- and Six-Rowed Barley Grown in Contrasting Nitrogen Environments

Two‐ and six‐rowed barley with different intrinsic ability to produce tillers and kernels per ear, would differ in responsiveness to nitrogen availability with environmental improvements. Two field experiments were carried out to elucidate how nitrogen supply (N₄₀ and N₁₅₀) affects yield and its components in two‐ and six‐rowed barley. High nitrogen increased aboveground dry matter at anthesis, by improving cumulative solar radiation intercepted by the crop, determining an increased dry‐matter production at maturity without changes in harvest index. In both barley types, variations in grain yield were explained by changes in kernels per unit land area rather than by differences in the average kernel weight. However, changes in the number of kernels were due to variations in the number of ears per m² in two‐rowed barley and the number of kernels per ear in six‐rowed barley. Ears per unit area showed a greater responsiveness in two‐ than in six‐rowed barley due to a higher nitrogen supply treatment, associated with their intrinsic higher tillering capacity, while the number of kernels per ear was more responsive in six‐ than in two‐rowed types. The fact that responses to nitrogen by the number of kernels per unit land area in two‐ and six‐rowed barley is better explained by different yield sub‐components, allows the speculation that the critical period for yield determination would differ between barley types.     

施氮对春玉米产量和经济效益的影响

采用随机区组设计试验,研究施氮对春玉米产量和经济效益的影响。结果表明,不同施氮量对春玉米经济性状、产量和经济效益的影响不同,各处理间产量差异极显著,以施氮量150kg/hm²的处理表现最佳;玉米产量和经济效益随施氮量的增加呈现先增加后降低的趋势;氮肥的农学效率随施氮量增加而降低。单位面积玉米产量和施氮量具有显著的回归关系,最高产量施氮量是:N161.9kg/hm²,最高产量为8351.9kg/hm²;最佳产量施氮量为:N144.7kg/hm²,最佳产量8324.1kg/hm²。