东北和西北春玉米氮磷钾养分吸收、积累特点比较

通过东北(吉林公主岭,JL-GZL)和西北(新疆伊犁71团,XJ-71)两个生态条件差异明显的大田试验,比较不同生态区春玉米植株养分吸收、积累差异。研究表明,西北试点的春玉米子粒产量、干物质积累量、氮磷钾等养分积累量均高于东北试点,其中,子粒产量、干物质积累量达极显著水平,叶片、茎秆、子粒氮、磷、钾养分积累量均达显著水平。东北春玉米叶片、茎秆氮含量较西北春玉米高,叶片、茎秆磷含量无显著差异,叶片、茎秆钾含量在整个生育期低于西北春玉米。西北春玉米每吸收1 kg氮所产生的子粒、干物质分别较东北春玉米高7.75%、7.11%,每吸收1 kg钾所产生的子粒、干物质分别较东北春玉米低9.12%、9.71%,每吸收1 kg磷所产生的子粒、干物质两个生态区无显著差异。氮磷钾收获指数与养分利用效率的变化趋势相同,西北试点氮收获指数高于东北试点,钾收获指数低于东北试点,磷收获指数无显著差异。     

Intraspecific Variation in Nitrogen Uptake and Nitrogen Utilization Efficiency in Wheat (Triticum aestivum L.)

Twenty wheat ( Triticum aestivum L.) varieties differing in plant height were grown in soil culture and evaluated for differences in nitrogen uptake and nitrogen utilization efficiency (NUE) at limited (40 kg N ha⁻¹) and normal (120 kg N ha⁻¹) nitrogen supply. Nitrogen uptake showed 1.4- and 1.5-fold varietal variation at harvest for limited and normal N supply, respectively. NUE for dry matter production (NE1) exhibited 1.28- and 1.38-fold genotypic variation while NUE for grain production (NE2) varied by 1.25- and 1.21-fold at limited and normal N supply, respectively. Tall varieties were found to have higher N uptake and NUE for dry matter production, while dwarf cultivars had greater NUE for grain production. Nitrogen uptake was found to be strongly positively associated with dry matter production (r=0.85 and r =0.77 at limited and normal N supply, respectively), indicating an important effect of growth rate on N uptake. NUE for biomass production, as well as for grain production, was reduced as the supply of nitrogen was increased.     

Effect of Neem Leaf (Azadirachta indica L.) on Growth and Yield of Low Land Rice

The farmers of tropical Asia are applying neem leaves to rice fields as green manure traditionally. Neem cake blending of urea is recommended for inhibition of nitrification and increasing nitrogen use efficiency. Field experiment conducted at the Tamil Nadu Agricultural University, Coimbatore, India, during kharif and rabi seasons in 1984–85 with a short duration (105 days) rice cv. IR 50 showed that application of fresh neem leaf at 5 t/ha or dry neem leaf 1.25 t/ha with urea resulted in higher N recovery per cent and N response ratio and gave increased grain yield compared to the yield obtained due to the application of urea alone. Besides increasing the grain yield, neem leaf application could save about 50 per cent N application and give greater net returns to the farmer.     

控释肥料的大蒜肥效研究

对控释肥料(CRFs)的大蒜肥效进行了田间试验,结果表明:控释肥料与普通肥料(OFs)相比,在肥料施用量低和中等时具有提高肥效、增加产量的作用,大蒜的生物量分别增加80.5%和51.1%,蒜苔和蒜头产量分别增加180%、100%、和69.2%、29.3%,而高用量时产量反而降低;在比普通肥料(300kg/hm2)减少一半用量的情况下,控释肥料(150kg/hm2)处理的大蒜生物量、蒜苔和蒜头产量分别增加15.6%、61.5%和11.6%。经过大蒜的整个生长季,控释肥料处理的根际土壤有效养分仍能维持较高的水平,控释肥料能显著提高大蒜体内的氮磷钾含量及肥料的养分利用率。     

灌溉水盐度和施氮量对棉花产量和水氮利用的影响

淡水资源不足和盐渍化是干旱半干旱地区农业生产的重要限制因素,因此提高水、 肥利用效率和作物产量,减少根区盐分积累和地下水污染风险是这些地区水分养分优化管理的重要目标。通过田间试验研究了滴灌条件下灌溉水盐度和施氮量对棉花产量和水、 氮利用率的影响。试验设置灌溉水盐度和施氮量两个因素,灌溉水盐度（电导率,EC）设3个水平,为0.35（淡水）、 4.61（微咸水）和 8.04（咸水）dS/m,分别用SF、 SM和SH表示;施氮（N）量设4个水平,为0、 240、 360和480 kg/hm2,分别以N0、 N1、 N2和N3表示。研究结果表明,棉花干物质重、 氮素吸收量和氮肥利用率受灌溉水盐度、 施氮量及二者交互作用的影响显著。咸水灌溉处理（SH）棉花干物质重、 氮素吸收量、 产量和氮肥表观利用率均显著降低,而微咸水灌溉（SM）对棉花氮素吸收量和氮肥表观利用率影响不大,但干物质重和产量有所降低。施氮肥可显著促进棉花生长,增加干物质重、 氮素吸收量和产量,但随着灌溉水盐度的增加,其促进效应明显受到抑制。微咸水和咸水灌溉会导致水分渗漏增加、 蒸散量降低,增施氮肥则可显著降低水分渗漏、 增加蒸散量。微咸水灌溉水分利用率最高,其次是淡水灌溉,咸水灌溉最低;增施氮肥则可显著提高水分利用率。因此滴灌条件下,高盐度的咸水不宜用于灌溉。而短期的微咸水灌溉不会对棉花产量和水、 氮利用率产生严重的负面影响;同时,合理的配施氮肥也有助于促进棉花生长,提高棉花产量和水分利用率。     

不同基因型油菜氮素利用效率的差异及其与农艺性状和氮素营养性状的关系

通过田间试验对50个甘蓝型油菜基因型进行氮利用效率筛选,并将不同氮利用效率基因型在施氮（N 180 kg/hm2）和不施氮（N 0 kg/hm2）条件下的农艺性状和氮营养性状作了比较研究。结果表明,50个油菜基因型的氮利用效率具有显著差异,最大相差2.5倍（施氮）和1.7倍（不施氮）。油菜的农艺性状及氮素营养性状指标均表现出一定的基因型变异,其中第一个有效分枝高度变异系数最大,超过 50%,而籽粒含氮量的变异系数最小,只有 6% 左右。不论供氮水平高低,氮高效基因型的每角粒数,籽粒生物量,籽粒占地上部生物量的比例以及籽粒氮占地上部总氮的比例均高于氮低效基因型,第一个有效分枝高度则显著低于氮低效基因型。另外,油菜氮素利用效率与各器官含氮量、 茎叶氮素累积量、 果荚氮素累积量、 茎叶氮占地上部氮的比例和果荚氮占地上部氮的比例呈显著或极显著负相关,而不同氮效率基因型的地上部总生物量和地上部氮素累积总量则无显著差异。不同氮利用效率基因型的农艺性状和氮营养性状对氮肥的敏感性有显著差异。     

EFFECTS OF PERENNIAL PEANUT AND COMMON BERMUDAGRASS ON NITROGEN AND WATER UPTAKE OF YOUNG CITRUS TREES

A greenhouse experiment was conducted using a Soil-N Uptake Monitoring (SUM) system to determine nitrogen (N) and water uptake dynamics of citrus (CIT), perennial peanut (PP) (Arachis glabrata Benth), and common bermudagrass (BG) (Cynodon dactylon L.) over time. We also assessed the competition for water and N uptake between citrus and groundcover species and compared citrus N uptake measured using the SUM system with the ¹⁵N method. Nitrogen uptake followed cyclic patterns and was greatest for bermudagrass-based systems, while values were similar for PP and citrus systems. Competition for N uptake did occur during the summer months between citrus and BG, while no obvious competition for N uptake occurred between citrus and PP. Water uptake was greatest for the mixed systems and BG monoculture. Citrus, PP, and BG competed for water during the spring and summer seasons. None of the groundcovers significantly affected overall citrus tree growth. Nitrogen use efficiency was greatest for mixed systems and bermudagrass.     

Identification of traits to improve the nitrogen-use efficiency of wheat genotypes

Nitrogen (N) fertilizer represents a significant cost for the grower and may also have environmental impacts through nitrate leaching and N₂O (a greenhouse gas) emissions associated with denitrification. The objectives of this study were to analyze the genetic variability in N-use efficiency (grain dry matter (DM) yield per unit N available from soil and fertilizer; NUE) in winter wheat and identify traits for improved NUE for application in breeding. Fourteen UK and French cultivars and two French advanced breeding lines were tested in a 2 year/four site network comprising different locations in France and in the UK. Detailed growth analysis was conducted at anthesis and harvest in experiments including DM and N partitioning. Senescence of either the flag leaf or the whole leaf canopy was assessed from a visual score every 3-4 days from anthesis to complete canopy senescence. The senescence score was fitted against thermal time using a five parameters monomolecular-logistic equation allowing the estimation of the timing of the onset and the rate of post-anthesis senescence. In each experiment, grain yield was reduced under low N (LN), with an average reduction of 2.2 t ha⁻¹ (29%). Significant N × genotype level interaction was observed for NUE. Crop N uptake at harvest on average was reduced from 227 kg N ha⁻¹ under high N (HN) to 109 kg N ha⁻¹ under LN conditions while N-utilization efficiency (grain DM yield per unit crop N uptake at harvest; NUtE) increased from 34.0 to 52.1 kg DM kg⁻¹ N. Overall genetic variability in NUE under LN related mainly to differences in NUtE rather than N-uptake efficiency (crop N uptake at harvest per unit N available from soil and fertilizer; NUpE). However, at one site there was also a positive correlation between NUpE and NUE at LN in both years. Moreover, across the 2 year/four site network, the N × genotype effect for NUpE partly explained the N × genotype effect for grain yield and NUE. Averaging across the 16 genotypes, the timing of onset of senescence explained 86% of the variation in NUtE amongst site-season-N treatment combinations. The linear regression of onset of senescence on NutE amongst genoytpes was not significant under HN, but at three of the four sites was significant under LN explaining 32-70% of the phenotypic variation amongst genotypes in NutE. Onset of senescence amongst genotypes was negatively correlated with the efficiency with which above-ground N at anthesis was remobilized to the grain under LN. It is concluded that delaying the onset of post-anthesis senescence may be an important trait for increasing grain yield of wheat grown under low N supply.     

基于计算机视觉和土壤Nmin的棉田氮素养分管理系统的建立与验证

[目的]报道一种基于计算机视觉和土壤(Nmin)的棉花氮素营养诊断和氮肥追肥推荐软件FertiExp系统的建立及其示范应用.[方法]通过棉花需氮量吸收模型、棉花吸氮量计算机视觉识别模型和土壤无机氮供应估算模型建立了FertiEXP软件系统.[结果]小区试验结果表明:采用FertiEXP进行氮肥追肥管理,氮肥利用率由37.85;提高到了56.02;,相对提高48.0;,产量基本持平.FetiEXP氮肥土壤中的残留量比常规管理减少100 kg/hm<'2>以上,氮素的表观损失率也大幅度降低.大田示范结果表明,采用FertiEXP推荐施肥,可以优化肥料在作物全生育期的分配比例,施N量降低6.7;～14.6;,而产量提高5.8;～7.5;.[结论]采用FertiEXP推荐施肥经济效益十分显著.     

水稻拔节期叶片碳氮代谢基因型差异及与氮素利用效率的关系

 采用土培盆栽试验,以3个氮素利用效率(NUE)有显著差异的水稻基因型秀恢2号(低NUE)、R83 12(中NUE)和五优244(高NUE)为材料,研究了拔节期叶片碳氮代谢的基因型差异及其与氮素高效利用的关系。结果表明,拔节期不同基因型水稻的叶片蔗糖和可溶性糖含量、淀粉/可溶性糖含量比和淀粉/蔗糖含量比存在极显著差异,前两者为五优244 > R83 12 >秀恢2号,后两者则相反;而淀粉和蔗糖/可溶性糖含量比各基因型差异不显著。不同基因型水稻的叶片全氮含量(TNC)、蛋白氮含量(PNC)、 PNC/TNC、Rubisco含量(RC)/PNC和RC/TNC存在极显著或显著差异,前两者为五优244 < R83 12 <秀恢2号, 后三者则相反;RC无基因型差异。五优244叶片的叶绿素a含量、类胡萝卜素含量、PSⅡ潜在活性、羧化效率、碳酸酐酶、酸性转化酶和蔗糖磷酸合成酶活性极显著或显著高于其他基因型;其叶片的硝酸还原酶、谷氨酰胺合成酶、谷氨酸合成酶和谷氨酸脱氢酶活性也极显著高于其他基因型。统计分析表明,高NUE水稻叶片具有较高的可溶性糖和蔗糖含量及较大的RC/TNC和RC/PNC,其生理基础是其叶片的高谷氨酰胺合成酶活性和PSⅡ潜在活性。