浮床植物对养殖池塘水质的影响研究   总被引：2，自引：2，他引：0  

钟全福 《中国农学通报》2015,31(5):70-74

为研究浮床植物对养殖的池塘净化作用,测定了NH₄⁺-N、NO₂^--N、NO₃^--N、PO₄^3--P、TN、TP、COD_Mn等主要水质指标。结果表明,在同样的试验条件下,池塘中各项水质指标按对照组、5%处理组、10%处理组、20%处理组的顺序逐渐降低;其中以20%处理组对NH₄⁺-N、NO₂^--N、NO₃^--N、PO₄^3--P、TN、TP、COD_Mn等主要水质指标去除率最大,分别为42.82%、39.47%、43.8%、64.1%、46.57%、58.75%、7.4%。通过6次空心菜的采收,空心菜的产量可达14.3~17.6 kg/m²;5%处理组、10%处理组、20%处理组通过采收空心菜直接从667 m²养殖池塘中移除TN分别为1643.5、2988.2、5341.3 g,移除TP分别为240.7、437.6、5341.3 g;同时处理组池塘罗非鱼的成活率明显高于对照组,由此可见,主养罗非鱼的养殖池塘中浮床栽培空心菜能够很好的净化水质,降低池塘富营养化。因此,建议20%的空心菜浮床覆盖率在罗非鱼养殖过程中具有一定的应用价值。  相似文献   

模拟降雨对稻田氮素损失修复效果的影响研究     

苗欢  乔云发  李清  苗淑杰 《中国农学通报》2023,(9):85-91

为探索减少稻田氮素流失的有效措施，研究暴雨下不同修复方式对稻田氮素流失的影响。采用盆栽试验和人工模拟降雨的方式，设置2个降雨强度(4、80 mm/h)和3个田面水层深度(2、5、8 cm)，选取秸秆还田和生物炭添加2种修复措施，研究了降雨强度与修复措施对雨后和水稻不同生育期稻田氮素流失的影响。结果表明：在相同降雨量条件下，与对照处理(NPK)相比，模拟4 mm/h降雨后，添加秸秆和生物炭处理田面水中的NH₄⁺-N浓度分别降低了15.1%和59.4%，然而，秸秆和生物炭处理田面水中NO₃^--N浓度略高于对照处理。当短时强降雨(80 mm/h)后，秸秆和生物炭处理田面水中的NH₄⁺-N浓度比对照分别降低55.4%和63.9%,NO₃^--N浓度比对照分别降低了38.7%和48.1%。在2个降雨强度条件下，田面水中NO₃^--N和NH₄⁺  相似文献   

硝态氮与铵态氮配合缓解黄瓜苗期铵毒害作用的研究     

樊娅萍  李静祎  贺苗苗  王倡宪 《中国农学通报》2024,(7):27-32

为明确硝态氮在缓解黄瓜苗期铵毒害的作用及相关机制,采用盆栽试验的方法,以‘津研4号’黄瓜为试验材料,以蛭石为育苗基质,在总氮浓度为15 mmol/L的条件下,苗期分别供给铵态氮与硝态氮,出苗5周后,测定黄瓜生长及生理相关指标。结果表明,在全NH₄⁺-N处理条件下,极易产生铵毒害。全NO₃^--N处理下,幼苗地上部全氮与全磷含量分别为全NH₄⁺-N处理的1.08倍与1.11倍,叶面积、生物量及壮苗指数显著高于全NH₄⁺-N处理;全NH₄⁺-N供给条件下,地上部MDA含量显著高于全NO₃^--N处理,而叶绿素含量却显著低于全NO₃^--N处理,生长明显受抑;在NH₄⁺-N中混入等量NO₃^--N后,抑制作用减...  相似文献   

小球藻对罗非鱼养殖水体水质及细菌群落结构的影响     

秦璐  陈曦  裘丽萍  范立民  宋超  郑尧  孟顺龙  陈家长 《中国农学通报》2021,37(12):112-120

本研究通过向罗非鱼养殖水体中添加小球藻,旨在探究其对养殖水体N、P降解和微生物群落调控的最佳浓度。分别设置对照组(NC)、低浓度组(LC)、中浓度组(MC)和高浓度组(HC),探究不同浓度小球藻对罗非鱼养殖水体中N、P的改善效果,并采用16S rRNA高通量测序技术分析养殖水体细菌群落结构变化。与其他处理组相比,HC组水体N、P营养盐含量降低,对3种形态氮的降解速率NH₄⁺-N>NO₃^--N>NO₂^--N。与NC组相比,MC组和HC组的微生物多样性降低;各处理组变形菌门(Proteobacteria)相对丰度增加,拟杆菌门(Bacteroidetes)相对丰度减少,且HC组拟杆菌门相对丰度最高,群落丰富度与NH₄⁺-N含量显著相关。小球藻可以吸收养殖水体中N、P营养盐,调节水体微生物群落结构,从而改善养殖水体水质状况,为养殖生产实践提供理论依据。  相似文献   

等氮量有机替代对水稻田面水氮素动态变化特征研究     

付斌  胡万里  倪明  李枝武  王炽  陈安强  闫辉  赵新梅  陈兴位  杨树明 《中国农学通报》2024,(11):36-43

为了防控高原湖泊流域稻田氮素径流流失,保护受纳水体生态环境。在洱海流域水旱轮作种植模式下,设置不施肥(CK)、单施化肥(NPK)、有机无机配施(NPKS)、有机肥全量替代(SS) 4个等氮量有机替代处理,研究水稻田面水氮素浓度的动态变化特征,探讨有机肥替代化肥施用对田面水氮素流失的影响。试验结果表明：基肥施用后田面水NH₄⁺-N、NO₃^--N、Org-N和TN浓度迅速升高,在3～7 d内达到峰值,施肥后7 d是防止田面水氮素大量流失的关键风险期。等氮量有机替代种植,田面水中NH₄⁺-N/TN浓度占比为39.01%～54.01%,NO₃^--N/TN浓度占比为11.33%～21.62%,Org-N/TN浓度占比为33.85%～41.94%。化肥氮施用增加田面水NH₄⁺-N/TN浓度占比,有机肥施用增加田面水NO₃^--N/TN和Or...  相似文献   

铵态氮与硝态氮不同配比对苣荬菜产量与品质的影响     

陈芳玲  王倡宪 《中国农学通报》2024,(10):29-34

为明确NH₄⁺-N与NO₃^--N不同配比对苣荬菜产量与品质的影响,采用盆栽试验的方法,以蛭石为栽培基质,在供氮总浓度为15 mmol/L的条件下,设置5个NH₄⁺-N与NO₃^--N配比(100/0、75/25、50/50、2575、0/100),出苗40 d后收获,测定产量及品质相关指标。结果表明,苣荬菜喜硝,其产量随NO₃^--N含量增加而增加,全NH₄⁺-N处理产量最低;同时,50/50处理与25/75处理间产量差异不显著,但前者的叶面积、地上部全氮含量、地上部全磷含量分别是后者的1.21、1.15、1.47倍。此外,50/50处理硝酸盐含量、维生素C含量分别是25/75处理的2.23、1.12倍,适当配合NH₄⁺-N可使硝酸盐含量显著降低至生食水平,并使叶绿素含量提高。研究认为,...  相似文献   

不同形态氮肥对黄瓜生长和营养元素吸收利用的影响     

班甜甜  李晓慧  马超 《分子植物育种》2024,(2):526-534

为了揭示同等氮水平下不同氮肥形态对黄瓜生长和营养元素吸收利用的影响。通过无土盆栽试验,研究6种同量不同形态氮肥处理(100%NH₄⁺-N,50%NO₃^--N+50%NH₄⁺-N,100%NO₃^--N,50%NO₃^--N+50%CO(NH₂)₂,100%CO(NH₂)₂,50%NH₄⁺-N+50%CO(NH₂)₂)对黄瓜生长指标和N、P、K、Ca、Mg、Fe的吸收与分配的影响。结果表明:50%NO₃^--N+50%CO(NH₂)₂处理时,干重、株高、蛋白质含量、氨基酸含量最高,100%NH₄<...  相似文献   

2种微生物菌剂对蔬菜花卉秸秆高温堆肥过程中氮变化的影响   总被引：1，自引：0，他引：1  

徐春钰  张仕颖  夏运生  潘丽媛  段红平  张乃明 《中国农学通报》2016,32(24):136-140

为寻求蔬菜花卉秸秆简单、有效的利用方法,减少滇池流域农业面源污染。通过堆肥试验研究了蔬菜花卉秸秆接种微生物菌剂农冠和微元后,在翻堆和不翻堆2种处理方式下,高温堆肥过程中温度、全氮(T-N)、水溶性NH₄ -N和水溶性NO₃^--N含量随时间的变化规律。结果表明：不翻堆的3个处理由于缺氧,发酵速率低,短期内不易腐熟。翻堆处理中,纯物料对照样品升温过程缓慢,高温分解阶段持续时间短, T-N损失大,堆肥品质差;添加微生物菌剂农冠后,与纯物料对照相比,提前3天进入高温分解阶段,高温分解持续时间延长4天,T-N含量损失比对照低10.9%,水溶性NH₄ -N比对照降低24.7%,水溶性NO₃^--N则比对照增加14.0%;添加微生物菌剂微元后,与纯物料对照相比,提前5天进入高温分解阶段,高温分解持续时间延长6天,T-N含量损失比对照低24.1%,水溶性NH₄ -N比对照降低29.3%,水溶性NO₃^--N则比对照增加24.2%。接种微生物菌剂可促进水溶性NH₄ -N向水溶性NO₃^--N转化,降低堆肥容重,其中添加微元综合效果更理想。在翻堆条件下接种微生物菌剂微元可加快蔬菜花卉秸秆堆肥化进程,提高堆肥产品品质,且方法简单易行,适合在全流域进行广泛推广。  相似文献   

不同氮素形态配比对饲料桑幼苗叶片叶绿素荧光特性和能量分配的影响   总被引：1，自引：0，他引：1  

许楠  钟海秀  沙威  伍一宁  张会慧  孙广玉 《中国农学通报》2015,31(26):18-25

为研究饲料桑‘青龙’幼苗叶片光合电子传递和分配对NH₄⁺-N和NO₃^--N不同形态氮配比的响应,以不同氮素形态配比为处理手段,通过测定饲料桑‘青龙’幼苗叶片的净光合速率响应曲线、以及荧光参数来测算光合电子传递速率和分配去向。结果表明,正常大气CO₂浓度[380 μmol/(m²·s)]处理下,饲料桑‘青龙’幼苗叶片较多的激发能以热量的形式耗散,n(NH₄⁺-N):n(NO₃^--N)为75:25至50:50时可使更多的激发能向光化学反应方向的分配,降低光合能量的热耗散速率,NO₃^--N浓度增加使激发能以热量的形式耗散增加;n(NH₄⁺-N):n(NO₃^--N)为100:0时饲料桑‘青龙’幼苗叶片参与光呼吸的非环式电子流速率(J₀)最高,随着n(NH₄⁺-N):n(NO₃^--N)为75:25时饲料桑‘青龙’幼苗叶片参与碳同化的非环式电子流速率J_c也升至最高。n(NH₄⁺-N):n(NO₃^--N)为50:50时激发能分配不平衡性系数(β/α-1)下降至最低,激发能分配系数达到平衡。荧光量子产额和热耗散的量子产额(Ф_f,D) n(NH₄⁺-N):n(NO₃^--N)为50:50至25:75范围时用于光化学反应的量子产额(Ф_PSⅡ)所占比例最高,依赖于类囊体膜两侧质子梯度和叶黄素循环的量子产额(Ф_NPQ)所占比例最低。该结果为探讨饲料桑‘青龙’幼苗光合作用电子流流向和激发能分配对不同氮素形态配比的响应规律,为饲料桑栽培中进行合理的苗期氮肥实施提供基础数据。  相似文献   

氮及氮素形态对烤烟叶片叶绿素光合荧光参数的影响     

黄丹  杨富文  刘琳  王月  贺国强  王洪瑞  孙广玉  敖红 《作物杂志》2021,37(1):150-494

为探明氮及氮素形态对烤烟叶片光合能力的影响,对烟草（Nicotiana tabacum L.）品种龙江911和龙江0520在无N（CK）、硝态氮（NO₃^--N）、铵态氮（NH₄⁺-N）及硝铵混合氮（NO₃^--N:NH₄⁺-N=1:1）处理下叶片气体交换参数及荧光动力学曲线的变化规律进行了研究。结果表明：施氮处理组的净光合速率（P_n）、气孔导度（G_s）及蒸腾速率（T_r）均高于CK,且随着时间的延长,升高幅度加大,差异达显著水平（P<0.05）。施氮总体上提高了2个烤烟品种F_v/F_m和光合性能指数（PI_abs）,说明氮促进了烤烟幼苗叶片光合系统Ⅱ（PSⅡ）反应中心的活性;同时施氮降低了V_J和V_I水平。对3种不同氮素形态下的荧光参数进行比较,发现NH₄⁺-N处理的荧光参数F_v/F_m和PI_abs偏低,而V_J和V_I偏高,说明NH₄⁺-N提高PSⅡ光合性能的能力相对较弱。综合光合气体交换参数和叶绿素荧光参数可知,NO₃^--N处理的龙江911和NO₃^--N:NH₄⁺-N（1:1）处理的龙江0520表现出更好的光合性能。  相似文献   

浮床栽培鱼腥草对吉富罗非鱼养殖池塘水质的影响   总被引：8，自引：5，他引：3  

郑尧  邴旭文  范立民  裘丽萍  宋超  孟顺龙  胡庚东  吴伟  徐跑  陈家长 《中国农学通报》2016,32(14):26-31

为研究浮床栽培鱼腥草(0、5%、10%和15%种植面积)对吉富罗非鱼养殖池塘的水质净化作用,测定了NH_4+~-N、NO_3~--N、NO_2~--N、TN、TP、CODMn等主要水质指标。结果表明,在同样的试验条件下,7—8月份鱼腥草处理组NO_3~--N下降,与此同时带来了NH_4~+-N(除5%处理组)和NO_2~--N的上升。9月份浮床栽培鱼腥草对5种水质指标的平均去除率在3%~38%之间。5%鱼腥草种植面积适合进行中试。通过鱼腥草的采收,5%鱼腥草处理组叶、根茎的产量分别可达112.4、1619.2 kg/hm~2,且可从养殖水体带走0.38 g/m~2的总氮,0.06 g/m~2的磷元素;同时收获鱼总重和所测生物学指标(除体重)显著高于对照和其他处理组,且对成活率和饵料系数无多大影响。  相似文献   

Time Course of Nitrogen in Soil Solution and Nitrogen Uptake in Maize Plants as affected by Form and Application Time of Fertilizer Nitrogen     

B. Buerkert    D. Horlacher  H. Marschner 《Journal of Agronomy and Crop Science》1995,174(5):325-336

Field experiments with silage maize were conducted in 1987 and 1988 on a loess-derived Luvisol in southwest Germany. Four nitrogen fertilizer treatments were compared: application of preplanting NH₄ N (plus a nitrification inhibitor, dicyandiamide as Didin) and preplanting NO₃-N, split application of NO₃-N (preplanting and side dressed 45 days after planting) and a control without nitrogen fertilizer in 1987 and with 64 kg N ha^?1 as calcium ammonium nitrate in 1988. The total amounts of soil mineral nitrogen (N_min+ fertilizer N) were 200 kg N ha^?1 in 1987 and 240 kg N ha^?1 in 1988. Suction cups and tensiometer were installed at five depths and samples were taken in regular intervals. Nitrate concentrations in the suction solution steeply increased at 15 cm and 45 cm soil depth 3-4 weeks after fertilizer application (1987 up to 160mgNl^?1; 1988 up to 170mgN l^?1) and steeply decreased up to 75 cm depth with the onset of intensive N uptake at shooting. Ammonium concentrations in the suction solution were very low (0-0.16 mg N l^?1). Compared to preplanting NCyN application, preplanting NH₄-N and split NO₃-N application decreased nitrate concentrations in the suction solution in spring 1987. In 1988, however, nitrate concentrations in the suction solution of preplanting NH₄-N and split NO₃-N application plots did not fall below 50mgNl^?1 at 15 cm depth during the growing season. Nitrate concentrations of split NO₃-N application increased again in autumn 1988 and hence doubled the calculated N losses by leaching during the winter months compared to preplanting N applications. At shooting, plants of the preplanting NH₄-N treatment had lower nitrate concentrations in leaf sheaths compared to plants of preplanting NO₃-N application. Total N uptake of maize between shooting and early grain filling of preplanting NH₄-N and split NO₃ -N application tended to be higher compared to preplanting NO₃-N application, reflecting the higher N availability in the soil later in the season. However, final dry matter yields and N uptake were not significantly affected by N form or time of N application. Since N losses by nitrate leaching between N application and onset of N uptake by plants were negligible on the experimental site, preplanting NH₄-N application and split NO₃-N application showed no agronomic advantages. High amounts of side dressed NO₃-N may increase nitrate leaching during the winter months, especially in years with delayed rainfall after application.  相似文献   

珠三角地区密养淡水鱼塘水体叶绿素a及水环境动态研究   总被引：1，自引：0，他引：1  

刘乾甫  赖子尼  王超  高原  杨婉玲  王广军 《中国农学通报》2015,31(2):138-145

于2012年5月—12月调查了珠三角地区主养笋壳鱼(Oxyeleotris marmoratus)、草鱼 (Ctenopharyngodon idellus)、加州鲈(Micropterus salmoides)和乌鳢(Channa argus)四个品种池塘水体中的叶绿素a(Chl a)含量和水环境因子动态变化。通过方差分析和多重比较方法研究池塘间水质因子的差异,使用逐步回归方法分析池塘中Chl a含量变化的影响因子,使用自组织神经网络(SOM)分析方法探讨池塘水质状况。研究结果显示：池塘水体TN、TP和化学耗氧量(Chemical Oxygen Demand,COD_Mn)变化范围分别为1.52~22.76 mg/L、0.20~4.82 mg/L和3.71~50.76 mg/L,呈现出严重富营养化和有机污染状况;池塘间Chl a含量差异显著（P<0.05）,从高到低顺序为：草鱼（均值）>乌鳢>加州鲈>笋壳鱼,各池塘Chl a含量的影响因子差异较大;乌鳢池塘中盐度（Sal）、电导率(Cond)、总可溶性固体(TDS)、TP、PO₄^3--P、TN、NO₃^--N和COD_Mn等因子显著高于其他品种(P<0.05);整个采样期池塘水质状况可分为5大类,并呈现出一定的时序和空间特征,池塘水质优劣顺序为笋壳鱼>加州鲈>草鱼>乌鳢。  相似文献   

施氮对墨西哥玉米植株硝态氮累积及产量的影响   总被引：14，自引：0，他引：14  

王永军  王空军  董树亭  胡昌浩  张吉旺  刘鹏 《作物学报》2006,32(3):345-350

采用微区试验研究了2个施氮水平（中氮,300 kg/hm²;高氮,600 kg/hm²）下2种施肥方式（一次基施和平均3次分施）对墨西哥玉米（Euchlaena mexicana）植株硝态氮（NO₃^--N）累积及产量的影响。结果表明,墨西哥玉米叶片中NO₃^--N含量以新生叶较高,全展叶较低,老叶居中;茎鞘和根系的NO₃^--N含量在不同收获期表现为第一收获期低于叶片,第二期仅比新生叶低,第三期则高于叶片。随着收获次数增加,NO₃^--N含量在叶片中呈降低趋势,在茎鞘和根系中先降后升。高氮水平和分次施肥是造成同一类型叶片NO₃^--N累积的主要原因;高氮分次施肥处理（N_2-3）第二期收获的新生叶NO₃^--N含量最高,为92.66 μg/g,这一数值尚未达动物摄食的潜在致毒剂量。氮素用量增加,其生产效率降低,但高氮（600 kg/hm²）一次性基施处理的干物质产量和粗蛋白质产量均显著高于其他处理。综上所述,较高的氮肥用量一次性基施能够实现墨西哥玉米的高产且不会影响其产品安全性。  相似文献   

甜菜亚硝酸还原酶基因(NiR)的克隆与表达分析   总被引：1，自引：0，他引：1  

石晓艳  曾彦达  李世龙  王玉波  马凤鸣  刁志伟 《作物学报》2011,37(8):1406-1414

以甜菜品种甜研7号叶片的cDNA为模板,采用RT-PCR和3′/5′RACE技术,获得了编码亚硝酸还原酶基因(NiR)的cDNA全序列2 014 bp, 包含有1 830 bp的开放阅读框,编码599个氨基酸。所推导的氨基酸序列与菠菜及拟南芥NiR编码的氨基酸序列均具93%的同源性。生物信息学分析表明,甜菜NiR具有完整的NiR蛋白结构,含血红素蛋白β-化合物区域和4Fe-4S区域, 并利用分析软件预测其三维结构。实时荧光定量结果显示,在以0、10、20、30、40、50、80和160 mmol L^–1 NO₃^–-N处理72 h的试验中,50 mmol L^–1处理可使甜菜NiR的表达量达到最大;以0、2、4、8、16、32、64和128 mmol L^–1 NH₄⁺-N处理48 h的试验表明,8 mmol L^–1和64 mmol L^–1处理条件下甜菜NiR表达量相对较高。硝态氮和铵态氮不同配比处理48 h的试验中,NO₃^–-N和NH₄⁺-N比例为80:20可使甜菜NiR的表达量达到最大;在氮素诱导的基础上,蛋白抑制剂放线菌酮处理9 h,随着处理浓度的增大,NiR的表达量逐渐下降;不同浓度NO₂^–处理的试验中,40 mmol L^–1处理下NiR的表达量最大。  相似文献   

Diagenesis in subrecent marine sediments in the Eastern Scheldt,Southwest Netherlands     

《Netherlands Journal of Sea Research》1988,22(3):253-265

The diagenesis in fine-grained sediments from a 300 to 400-years-old Dunkirk deposit, exposed on the intertidal flat, was studied at a site in the Eastern Scheldt. A new in situ pore water sampling technique that allowed repeated sampling at exactly the same place was used to monitor the seasonal fluctuations in interstitial water composition.Concentrations of organic carbon (1.5 to 2%), nitrogen (C/N = 19), phosphorus (500 μg·g⁻¹) and manganese (250 μg·g⁻¹) in the subrecent anoxic sediments were low, probably because they had already been depleted during earlier stages of diagenesis. Rates of organic carbon mineralization by sulphate reduction (0.1 Mole·m⁻²·y⁻¹) and rates of nutrient regeneration were 1 to 2 orders of magnitude lower than in recent fine-grained sediments elsewhere in the Eastern Scheldt.Pore water NH₄⁺ and ΣPO₄ concentrations were controlled by mineralization, uptake by Zostera noltii and sediment-seawater exchange. During the summer the uptake exceeded the mineralization rate at 0 to 5 cm. Mineralization and diffusional processes dominated the changes in the NH₄⁺ and ΣPO₄ profiles in the other seasons.Dissolved manganese and iron concentrations showed a typical subsurface maximum at 0 to 3 cm, and low (<5 μMole) concentrations below this depth. Dissolved iron concentrations were probably controlled by the solubility of iron sulphides, and manganese probably by the solubility of Mn, Ca-carbonate.  相似文献   

Rice–weed competition in response to nitrogen form under high and low transpirational demand     

Duy Hoang Vu  Sabine Stuerz  Folkard Asch 《Journal of Agronomy and Crop Science》2023,209(1):27-40

Implementation of water-saving irrigation practices in lowland rice results in increased availability of nitrate (NO₃⁻) in the soil and favours germination of upland weeds. Since plant species show a specific preference for either ammonium (NH₄⁺) or NO₃⁻ as nitrogen (N) source, changes in both soil NO₃⁻ concentration and weed flora may affect the competition between rice and weeds. Further, the transpirational demand of the atmosphere might affect growth and competitiveness of lowland (wetland) and upland (dryland) weeds differently due to their adaptation to different ecological environments. Therefore, the study aimed to evaluate the effects of N source on growth, N uptake and competition between rice and common upland and lowland weeds under high and low vapour pressure deficit (VPD). Two rice (Oryza sativa) varieties (NU838 and KD18) differing in growth characteristics and two weed species (Echinochloa crus-galli and Solanum nigrum) differing in their natural habitat were selected and grown hydroponically as monoculture or mixed culture at low or high VPD. N was supplied as 75%/25% or 25%/75% NH₄⁺/NO₃⁻. N uptake rates were measured in the first week, whereas dry matter (DM), N concentration in the plant, total N uptake and the activities of nitrate reductase and glutamine synthetase in the fresh leaves were determined two weeks after the onset of treatments. Independent of N source, both rice varieties and E. crus-galli took up a larger share of NH₄⁺, whereas S. nigrum took up a larger share of NO₃⁻. N uptake of rice and E. crus-galli was hardly affected by N source, whereas high NO₃⁻ led to significantly higher N uptake rates and total N uptake of S. nigrum. NU838 showed a higher competitiveness against weeds than KD18. In competition, high NO₃⁻ decreased the competitiveness of E. crus-galli against NU838 but increased the competitiveness of S. nigrum against NU838. High VPD did not affect DM but increased N uptake of S. nigrum, leading to increased competitiveness of the weed at high transpirational demand. Competitiveness for N uptake appears to be an important trait as the relative N concentration in mixed plant communities was correlated with the activity of N-assimilating enzymes and leaf growth, with a stronger response in rice than in weeds. Our results support the hypothesis that increased availability of NO₃⁻ in aerobic rice soils may be advantageous for the competitiveness of upland weeds, especially at high VPD, whereas it may be disadvantageous for common lowland weeds.  相似文献   

不同氮素用量对黄瓜幼苗生长及养分吸收的影响     

司东霞  李海云  吕福堂  褚鹏飞  吕新春 《中国农学通报》2016,32(19):46-50

为确定黄瓜幼苗对氮素用量及氮素形态的响应特性以指导育苗期间合理施肥,以硝酸铵磷（NO3--N:NH4+-N为0.9:1.0）为供试肥料,研究同时提供NO3--N和NH4+-N的情况下,不同氮素用量对黄瓜幼苗生长及养分吸收的影响。结果表明：与不施氮对照相比,氮素施用可显著增加植株叶面积和株高,但各施氮处理之间差异不明显（50~200 mg N/株）;植株幼苗茎粗和地上部干物质累积量不同处理间差异不显著;施用氮素黄瓜幼苗根系的根长、根表面积和干物质累积量降低（尤其氮用量100 mg/株）,根系直径在0.5~1.3 mm和1.8~2.6 mm范围内的根长下降明显。氮素用量显著影响了地上部氮、磷、钾的浓度及吸收量,对根系的磷、钾浓度和氮、磷、钾的吸收量影响较小;综合地上部和根系的生长状况,氮素用量在50 mg/株及150 mg/株时,黄瓜幼苗的生长健壮。  相似文献   

Turnover and fate of 15N-labelled cattle slurry ammonium-N applied in the autumn to winter wheat     

《European Journal of Agronomy》2000,12(1):23-35

The fate of ¹⁵NH₄-N labelled cattle slurry applied before sowing in September of a winter wheat crop was studied on a loamy sand soil. The aim was to quantify immobilization of slurry NH₄-N into microbial biomass, the speed at which nitrate derived from the slurry NH₄-N was transported down the soil profile, and the utilization of slurry NH₄-N by the winter wheat crop. Cattle slurry was applied at a rate corresponding to 75 kg NH₄-N ha⁻¹ , with very little loss by volatilization (<4%) due to rapid incorporation by ploughing. The slurry amendment resulted in a doubling of soil surface CO₂ flux, an index of microbial activity, over non-amended soil within the first c. 2 weeks, but ceased again after c. 4 weeks, due to depletion of the easily degradable substances, e.g. volatile fatty acids, in the slurry. Nitrification of the applied NH₄-N was fast and complete by 3 weeks from application, and at this time, the maximum immobilization of slurry NH₄-N into the microbial biomass (23% of applied ¹⁵NH₄-N) was also observed, although no significant increase in total microbial biomass was observed. Rapid turnover of the microbial biomass quickly diluted the assimilated ¹⁵N, with only 6% of applied ¹⁵NH₄-N remaining in the microbial biomass by next spring. Downwards transport of nitrate was rapid in spite of lower than normal precipitation, and slurry-derived ¹⁵NO₃-N appeared in ceramic suction cups installed at 60 cm depth already 2 months after slurry application. Due to the unusually low winter precipitation in the experimental year, wheat yields were high, and the recovery of N in above-ground plant biomass derived from slurry NH₄-N at harvest reached 32%. An additional 45% of the applied slurry NH₄-N could be found in the soil to a depth of 100 cm (mostly in organic form in the plough layer), indicating that 23% had been lost by leaching or in gaseous form. It was concluded that although significant immobilization of slurry NH₄-N did occur, this was not sufficient to prevent leaching of slurry-derived N over the winter and that the relatively high recovery of slurry-derived N in the wheat crop was due partly to lower than normal winter percolation and partly to a relatively high rooting depth on this particular site.  相似文献