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Changes in foliar nitrogen resorption of Phyllostachys edulis with culm development 预览
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作者 Changshun Zhang Chunlan Liu +3 位作者 Wenyuan Zhang Gaodi Xie Shaohui Fan Na Li 《林业研究:英文版》 CAS CSCD 2019年第2期417-427,共11页
Leaf nitrogen resorption is very important to Phyllostachys edulis development because the withdrawn nitrogen can help newly emerging and growing culms.However,few studies have focused on the ontogenetic changes in le... Leaf nitrogen resorption is very important to Phyllostachys edulis development because the withdrawn nitrogen can help newly emerging and growing culms.However,few studies have focused on the ontogenetic changes in leaf nitrogen resorption of P.edulis.Here,we examined the variability in mature leaf nitrogen concentrations(Nm),nitrogen resorption efficiency(NRE)and proficiency(NRP or Ns)and leaf-level nitrogen use efficiency(NUE)of the current-,3rd-and 5th-year culms in P.edulis stands under extensive management.Analyses of variance and correlation indicated that patterns of Nm,NRP,NRE and NUE were markedly affected by culm age and leaf nitrogen status.Nm,Ns and NRE were significant higher in younger(current-year)culms with 1-year lifespan leaves,while NUE was markedly higher in older(3rd-or 5th-year)culms with 2-year lifespan leaves.Significant linear correlations between Nm and NRP,NRE and NUE,Nm and NUE,Ns and NRE were found for each culm age,and Nm was significantly positively correlated to NRE for all culms pooled.Higher proficiency in older culms led to higher NUE and lower NRE,these relationships can be modulated by Nm,which in turn,is restrained by leaf N availability and acquisition.Our results revealed that at the intraspecific level,P.edulis can adjust its leaf NRE,NRP,and leaf-level NUE in concert with culm development.Understanding nitrogen resorption characteristics and NUE of P.edulis can help decision-makers design appropriate deforestation strategies and achieve precise N fertilization for sustainable bamboo forest management. 展开更多
关键词 Phyllostachys EDULIS NITROGEN RESORPTION EFFICIENCY NITROGEN RESORPTION proficiency Nitrogen-use EFFICIENCY Extensive management CULM DEVELOPMENT Precision fertilization
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Nitrogen-cycling microbial community functional potential and enzyme activities in cultured biofilms with response to inorganic nitrogen availability
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作者 Shuangshuang Li Chengrong Peng +3 位作者 Taisheng Chen Chun Wang Liangliang Guo Dunhai Li 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第2期89-99,共11页
Biofilms mediate crucial biochemical processes in aquatic ecosystems. It was hypothesized that eutrophication may promote the growth of biofilms, resulting in larger numbers of functional genes. However, the metabolic... Biofilms mediate crucial biochemical processes in aquatic ecosystems. It was hypothesized that eutrophication may promote the growth of biofilms, resulting in larger numbers of functional genes. However, the metabolic activity and the roles of biofilms in N cycling will be affected by ambient inorganic nitrogen availability, not by the abundance of functional genes. Biofilms were cultured either with replete inorganic nitrogen (N-rep) or without exogenous inorganic nitrogen supply (N-def) in a flow incubator, and the N-cycling gene abundances (nifH, N2 fixation;amoA, ammonia oxidation, archaea and bacteria;nirS and nirK, denitrification) and enzyme activities (nitrogenase and nitrate reductase) were analyzed. The results showed that, comparing the N-def and N-rep biofilms, the former contained lower nifH gene abundance, but higher nitrogenase activity (NA), while the latter contained higher nifH gene abundance, but lower NA. Different patterns of NA diel variations corresponded to the dynamic microbial community composition and different stages of biofilm colonization. Ammonia oxidizing bacteria (AOB), detected only in N-def biofilms, were responsible for nitrification in biofilms. N-rep biofilms contained high nirS and nirK gene abundance and high denitrification enzyme activity, but N-def biofilms contained significantly lower denitrification gene abundance and activity. In general, the strong N2 fixation in N-def biofilms and strong denitrification in N-rep biofilms assured the balance of aquatic ecosystems. The results suggested that evaluation of the functional processes of N cycling should not only focus on genetic potential, but also on the physiological activity of biofilms. 展开更多
关键词 CULTURED biofilms NITROGEN AVAILABILITY Nitrogen-cycling enzymes Nitrogen-cycling genes
草甸白浆土稻秆氮利用效率及氮素调控对水稻产量的影响 预览
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作者 王秋菊 焦峰 +3 位作者 刘峰 迟凤琴 姜辉 李鹏绯 《农业工程学报》 EI CAS CSCD 北大核心 2019年第11期86-94,共9页
为明确三江平原草甸白浆土水稻秸秆还田条件下如何进行施肥,以期为秸秆全量还田条件下水稻氮肥的优化施用提供理论依据和技术指导。该文在白浆土上进行了秸秆氮利用试验、秸秆还田氮素优化施用试验、及氮素调控时期的试验研究。结果表明... 为明确三江平原草甸白浆土水稻秸秆还田条件下如何进行施肥,以期为秸秆全量还田条件下水稻氮肥的优化施用提供理论依据和技术指导。该文在白浆土上进行了秸秆氮利用试验、秸秆还田氮素优化施用试验、及氮素调控时期的试验研究。结果表明:通过15N同位素示踪确定,秸秆氮对水稻植株氮素累积量贡献率为6.49%~7.48%,对茎叶氮素累积量的贡献率为3.26%~4.16%,对籽粒贡献率为8.67%~9.74%;秸秆氮素当年总利用率为6.51%~7.65%;调节碳/氮比有利于提高秸秆氮素利用率。大田试验证实秸秆还田条件下施氮量连续3a比常规施氮量减少10%,排水性好的田块有增产效果,3a平均增产6.17%,减氮20%以上产量低而且年际间不稳,减氮时期适合均衡减氮和基肥减氮,蘖肥和穗肥减氮减产极显著;排水性不良田不适合减氮,减氮导致减产。不同土壤秸秆还田后氮素调控有差异,要因地制宜根据土壤条件制定相应的氮素管理措施。 展开更多
关键词 土壤 秸秆 白浆土 秸秆还田 15N标记 氮利用率 氮素调控 产量
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Estimating total leaf nitrogen concentration in winter wheat by canopy hyperspectral data and nitrogen vertical distribution 预览
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作者 DUAN Dan-dan ZHAO Chun-jiang +6 位作者 LI Zhen-hai YANG Gui-jun ZHAO Yu QIAO Xiao-jun ZHANG Yun-he ZHANG Lai-xi YANG Wu-de 《农业科学学报:英文版》 SCIE CAS CSCD 2019年第7期1562-1570,共9页
The use of remote sensing to monitor nitrogen(N) in crops is important for obtaining both economic benefit and ecological value because it helps to improve the efficiency of fertilization and reduces the ecological an... The use of remote sensing to monitor nitrogen(N) in crops is important for obtaining both economic benefit and ecological value because it helps to improve the efficiency of fertilization and reduces the ecological and environmental burden.In this study,we model the total leaf N concentration(TLNC) in winter wheat constructed from hyperspectral data by considering the vertical N distribution(VND).The field hyperspectral data of winter wheat acquired during the 2013–2014 growing season were used to construct and validate the model.The results show that:(1) the vertical distribution law of LNC was distinct,presenting a quadratic polynomial tendency from the top layer to the bottom layer.(2) The effective layer for remote sensing detection varied at different growth stages.The entire canopy,the three upper layers,the three upper layers,and the top layer are the effective layers at the jointing stage,flag leaf stage,flowering stages,and filling stage,respectively.(3) The TLNC model considering the VND has high predicting accuracy and stability.For models based on the greenness index(GI),mND705(modified normalized difference 705),and normalized difference vegetation index(NDVI),the values for the determining coefficient(R2),and normalized root mean square error(nRMSE) are 0.61 and 8.84%,0.59 and 8.89%,and 0.53 and 9.37%,respectively.Therefore,the LNC model with VND provides an accurate and non-destructive method to monitor N levels in the field. 展开更多
关键词 NITROGEN concentration HYPERSPECTRAL vertical NITROGEN distribution winter WHEAT
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氮钾肥配施对辽东南地区玉米生长及氮素积累的影响 预览
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作者 樊叶 樊琳琳 +3 位作者 薛兵东 王秀凤 付俊 张丽丽 《河北农业大学学报》 CAS CSCD 北大核心 2019年第1期8-13,共6页
试验针对辽东南地区气候特点,设置二因素裂区试验,研究不同氮、钾肥配施对玉米生长特性及养分吸收规律的影响。结果表明:氮肥可有效延长叶片的功能期,减缓吐丝期至灌浆期LAI的下降幅度,下降幅度依次为N300(2.69%)<N180(16.13%)<N9... 试验针对辽东南地区气候特点,设置二因素裂区试验,研究不同氮、钾肥配施对玉米生长特性及养分吸收规律的影响。结果表明:氮肥可有效延长叶片的功能期,减缓吐丝期至灌浆期LAI的下降幅度,下降幅度依次为N300(2.69%)<N180(16.13%)<N90(28.62%)<N0(46.84%);植株氮素积累的2个主要阶段分别在大喇叭口期至吐丝期和吐丝期至灌浆期,N300、N180、N90和N0从大喇叭口期至灌浆期的氮素积累量分别占整个生育期氮素积累量的65%、63%、51%和60%;氮、钾肥对玉米产量、吐丝期和灌浆期的LAI及灌浆期和成熟期的氮素积累量有显著的互作效应;在辽东南地区,氮、钾肥通过促进玉米植株营养生长,提高群体的LAI和叶片叶绿素含量,增强群体光合能力的同时,还通过促进植株对氮、钾元素的吸收与利用,提高植株的氮素积累能力,从而实现玉米高产。 展开更多
关键词 玉米 氮肥 钾肥 氮素积累 辽东南地区
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基于便携式作物生长监测诊断仪的江西双季稻氮肥调控研究 预览
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作者 李艳大 舒时富 +5 位作者 陈立才 叶春 黄俊宝 孙滨峰 王康军 曹中盛 《农业工程学报》 EI CAS CSCD 北大核心 2019年第2期100-106,共7页
建立基于便携式作物生长监测诊断仪的江西双季稻氮肥调控模型,利用模型推荐穗肥追氮量,实现江西双季稻氮肥追施的精确管理。基于不同株型品种和氮肥处理的田间试验资料,构建了双季稻叶面积指数光谱监测模型,利用拔节期的差值植被指数实... 建立基于便携式作物生长监测诊断仪的江西双季稻氮肥调控模型,利用模型推荐穗肥追氮量,实现江西双季稻氮肥追施的精确管理。基于不同株型品种和氮肥处理的田间试验资料,构建了双季稻叶面积指数光谱监测模型,利用拔节期的差值植被指数实时估测叶面积指数,进而结合江西双季稻高产栽培经验和建立的氮肥调控模型,对双季稻穗肥追氮量进行实时推荐,并和当地农户施肥方案和产量进行比较。双季稻关键生育期(分蘖期、拔节期、孕穗期、抽穗期和灌浆期)的冠层差值植被指数DVI(810,720)与叶面积指数均呈显著正相关,线性函数拟合效果优于其他函数。利用独立试验资料对所建模型进行了检验,单生育期的模型预测效果优于全生育期模型;其中,拔节期的光谱监测模型表现最佳,早稻和晚稻叶面积指数的光谱监测模型的R2分别为0.8806和0.8788,模型预测早稻和晚稻叶面积指数的均方根误差、相对均方根误差、相关系数分别为0.30和0.25、7.28%和6.18%、0.9232和0.9269。氮肥调控模型推荐施肥应用表明,紧凑型品种的穗肥用量高于松散型品种;与农户方案相比,氮肥调控模型推荐施肥的调控方案在产量不降低的情况下减少氮肥用量6.58kg/hm^2,提高氮肥农学利用率0.82个百分点、净收益103元/hm^2和产投比0.9,而产量比农户方案略高或持平。与传统非定量农户施肥法相比,基于便携式作物生长监测诊断仪的双季稻氮肥调控方法可在保证产量的情况下,减少施氮量,提高氮肥农学利用率,获得更高经济效益,在江西双季稻生产中具有推广应用价值。 展开更多
关键词 肥料 作物 便携式作物生长监测诊断仪 双季稻 差值植被指数 氮肥调控 叶面积指数 产量
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Isotope analysis of nitrate pollution sources in groundwater of Dong'e geohydrological unit 预览
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作者 LI Yang KANG Feng-Xin ZOU An-de 《地下水科学与工程:英文版》 2019年第2期145-154,共10页
As nitrate pollution in groundwater has become increasingly serious in recent years, nitrogen isotope was adopted in this paper to define its sources in a typical agricultural area of Dong5e hydrogeological unit. The ... As nitrate pollution in groundwater has become increasingly serious in recent years, nitrogen isotope was adopted in this paper to define its sources in a typical agricultural area of Dong5e hydrogeological unit. The results show that: Higher content of NO3^- detected in shallow groundwater is 27.77 mg/L on average and δ^15N content ranges from 7.8‰ to 12 ‰, indicating that shallow groundwater is mainly contaminated by sewage or feces. In contrast, less NO3^- in deep groundwater (karst water) has an average value of 12.81 mg/L and δ^15N content is between 7.2‰ and 14.3‰, which is closely related to human disturbance as mentioned above. In addition, considering relatively low groundwater quality at some monitoring sites, reasonable fertilization is a better choice in the study area to reduce nitrate source in groundwater. 展开更多
关键词 NITROGEN ISOTOPE GROUNDWATER NITROGEN POLLUTION source AGRICULTURAL area
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9个主要南方人工林树种叶片化学计量学特征研究 预览
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作者 王家妍 魏国余 +2 位作者 韦铄星 莫雅芳 蒋燚 《广东农业科学》 CAS 2019年第5期48-53,共6页
【目的】通过研究9个主要南方人工林树种叶片N、P、K化学计量学特征,丰富主要人工林树种化学计量学基础数据,为我国南方地区林木种植和管护提供决策依据。【方法】野外平均木叶片采集,室内进行化学测定分析N、P、K含量。【结果】9个树... 【目的】通过研究9个主要南方人工林树种叶片N、P、K化学计量学特征,丰富主要人工林树种化学计量学基础数据,为我国南方地区林木种植和管护提供决策依据。【方法】野外平均木叶片采集,室内进行化学测定分析N、P、K含量。【结果】9个树种叶片的N、P、K含量均值分别为13.90、1.39、8.70 mg/g,不同树种间的N、P、K含量存在极显著差异,厚荚相思N、P、K含量高于其他树种, 9个树种叶片的N∶P、N∶K和K∶P变化范围为7.79~17.79、1.15~2.16、0.07~0.25。不同树种N和P含量呈极显著正相关关系,存在协同作用。不同生活型树种叶片N和P元素含量存在极显著差异,表现为阔叶树种N和P含量明显大于针叶林。【结论】9个主要南方人工林树种生长主要受到N元素限制,在林分后期管理上应加强养分管理、增施氮肥。 展开更多
关键词 氮磷比 化学计量学 阔叶树种 针叶树种
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碳氮添加对雨养农田土壤全氮、有机碳及其组分的影响 预览
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作者 江晶 武均 +2 位作者 张仁陟 董博 蔡立群 《水土保持学报》 CSCD 北大核心 2019年第3期215-220,227共7页
为探明碳氮添加4年后,土壤全氮、有机碳及其组分(可溶性有机碳、微生物量碳、轻组和重组有机碳)的变化特征,依托布设于甘肃省定西市安定区李家堡镇的不同碳源配施氮素田间定位试验,涉及秸秆、生物质炭、氮素3个因素,秸秆设置为不施、施... 为探明碳氮添加4年后,土壤全氮、有机碳及其组分(可溶性有机碳、微生物量碳、轻组和重组有机碳)的变化特征,依托布设于甘肃省定西市安定区李家堡镇的不同碳源配施氮素田间定位试验,涉及秸秆、生物质炭、氮素3个因素,秸秆设置为不施、施用秸秆2水平;生物质炭为不施和施用生物质炭2个水平;氮素设置为不施氮、施纯氮50 kg/hm~2、施纯氮100 kg/hm~2 3个水平,共9个处理。结果表明:不同处理下土壤全氮、有机碳及其组分的含量均随土层的加深而降低。添加生物质炭对土壤全氮、有机碳及其组分均具有不同程度的提升效应。添加秸秆对土壤全氮、有机碳和可溶性有机碳、微生物量碳、轻组有机碳均具有显著提升效应,仅在0-5 cm土层对重组有机碳有显著提高。添加氮素可显著提升土壤全氮、有机碳和可溶性有机碳、微生物量碳、轻组有机碳含量。较其他处理,添加生物质炭对土壤全氮、有机碳和重组有机碳的提升效应最高,添加秸秆对可溶性有机碳、微生物量碳、轻组有机碳的提升效果最优。从提升土壤质量的角度出发,推荐秸秆配施氮素模式,该模式下土壤碳素有效性高、易于被微生物利用,有利于作物生长。从提高土壤固碳角度考虑,推荐生物质炭配施氮素模式,该模式有利于碳的封存。 展开更多
关键词 生物质炭 秸秆 氮素 全氮 有机碳组分
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Nitrogen additions inhibit nitrification in acidic soils in a subtropical pine plantation:effects of soil pH and compositional shifts in microbial groups 预览
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作者 Liang Kou Xinyu Zhang +3 位作者 Huimin Wang Hao Yang Wei Zhao Shenggong Li 《林业研究:英文版》 CAS CSCD 2019年第2期669-678,共10页
Plantation forests play a pivotal role in carbon sequestration in terrestrial ecosystems,but enhanced nitrogen(N)deposition in these forests may affect plantation productivity by altering soil N cycling.Hence,understa... Plantation forests play a pivotal role in carbon sequestration in terrestrial ecosystems,but enhanced nitrogen(N)deposition in these forests may affect plantation productivity by altering soil N cycling.Hence,understanding how simulated N deposition affects the rate and direction of soil N transformation is critically important in predicting responses of plantation productivity in the context of N loading.This study reports the effects of N addition rate(0,40,and 120 kg N ha^-1 a^-1)and form(NH4Cl vs.NaNO3)on net N mineralization and nitrification estimated by in situ soil core incubation and on-soil microbial biomass determined by the phospholipid fatty acid(PLFA)method in a subtropical pine plantation.N additions had no influences on net N mineralization throughout the year.Net nitrification rate was significantly reduced by additions of both NH4Cl(71.5)and NaNO3(47.1%)during the active growing season,with the stronger inhibitory effect at high N rates.Soil pH was markedly decreased by 0.16 units by NH4Cl additions.N inputs significantly decreased the ratio of fungal-to-bacterial PLFAs on average by 0.28(49.1%)in November.Under NH4Cl additions,nitrification was positively related with fungal biomass and soil pH.Under NaNO3 additions,nitrification was positively related with all microbial groups except for bacterial biomass.We conclude that simulated N deposition inhibited net nitrification in the acidic soils of a subtropical plantation forest in China,primarily due to accelerated soil acidification and compositional shifts in microbial functional groups.These findings may facilitate a better mechanistic understanding of soil N cycling in the context of N loading. 展开更多
关键词 ACIDIFICATION Atmospheric NITROGEN deposition MICROBIAL functional group NITRIFICATION Soil NITROGEN transformation
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Comprehensive analysis of nitrogen distributions and ammonia nitrogen release fluxes in the sediments of Baiyangdian Lake, China
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作者 Yaoyao Zhu Xin Jin +2 位作者 Wenzhong Tang Xin Meng Baoqing Shan 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第2期319-328,共10页
The condition of Baiyangdian Lake (BYDL) will improve as the Xiongan New Area evolves and fulfills its role of easing overcrowding and supporting economic growth. Water and sediment samples from BYDL were analyzed to ... The condition of Baiyangdian Lake (BYDL) will improve as the Xiongan New Area evolves and fulfills its role of easing overcrowding and supporting economic growth. Water and sediment samples from BYDL were analyzed to provide information on nitrogen (N) contamination in BYDL. The mean ammonium N (NH4^+-N), nitrate N, and total N concentrations in the water samples were 0.36, 0.12, and 2.22mg/L, respectively, and the ranges were 0.003–8.38, 0.06–0.30, and 1.25–10.34mg/L, respectively. The N concentrations in water gradually increased from the north to the south of BYDL. Sediment at 90% of the sampling sites was in or above the moderately contaminated class (1000–2000mg/kg) defined in US Environmental Protection Agency total N pollution standards. Positive NH4^+-N fluxes were found for 28 of the 34 sediment core samples, so the potential for NH4+-N being released from sediment was relatively high. The NH4^+-N fluxes were 5.35–48.76mg/m^2/day, and the mean and maximum fluxes were 8.71 and 48.76mg/m^2/day, respectively. Benthic organisms will be affected more by NH4^+-N and NH3·H2O in the surface sediment pore water (mean concentrations 4.93 and 0.13mg/L, respectively) than by the other forms of N. 展开更多
关键词 NITROGEN AMMONIA NITROGEN Baiyangdian LAKE FLUX SEDIMENT
氮、钾运筹对设施番茄产量、果实硝酸盐含量及土壤硝态氮含量的影响 预览
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作者 董环 娄春荣 +2 位作者 王秀娟 赵颖 何志刚 《江苏农业学报》 CSCD 北大核心 2019年第2期378-383,共6页
施肥影响设施蔬菜的产量、质量安全和土壤环境,因此,开展设施番茄氮肥和钾肥配合施用方案的研究,对区域设施农业优质、高效、健康发展具有重要意义。本研究以番茄新品种辽粉185为试验材料,采用氮、钾2因素4水平完全随机设计,探讨氮、钾... 施肥影响设施蔬菜的产量、质量安全和土壤环境,因此,开展设施番茄氮肥和钾肥配合施用方案的研究,对区域设施农业优质、高效、健康发展具有重要意义。本研究以番茄新品种辽粉185为试验材料,采用氮、钾2因素4水平完全随机设计,探讨氮、钾配合施用对设施番茄产量、果实硝酸盐含量及土壤硝态氮含量的影响。结果表明,果实硝酸盐含量随氮和钾施入水平的提升而增加,土壤硝态氮含量随氮施入水平的提升而增加,随钾施入水平的提升而降低。氮、钾施入水平对番茄产量的影响均为先促进后抑制,通过回归模型获得番茄最高产量的氮、钾推荐施肥量分别为323.6kg/hm^2和377.0kg/hm^2。采用TOPSIS(Technique for order preference by similarity to an ideal solution)法进行综合评价,获得的结果表明,氮是影响番茄产量、质量安全和环境的重要因素,氮投入142.9~285.7kg/hm^2可作为区域设施番茄栽培决策施肥的参考区间。 展开更多
关键词 设施番茄 产量 果实硝酸盐 土壤硝态氮
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基于无人机多光谱影像的夏玉米叶片氮含量遥感估测 预览
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作者 魏鹏飞 徐新刚 +7 位作者 李中元 杨贵军 李振海 冯海宽 陈帼 范玲玲 王玉龙 刘帅兵 《农业工程学报》 EI CAS CSCD 北大核心 2019年第8期126-133,I0001共9页
利用无人机平台搭载多光谱相机组成的遥感监测系统在农业上已取得了一些成果,但利用无人机多光谱影像开展作物氮素估测研究少有尝试。基于此,该文利用国家精准农业基地2017年夏玉米3个关键生育期无人机多光谱影像和田间实测叶片氮含量数... 利用无人机平台搭载多光谱相机组成的遥感监测系统在农业上已取得了一些成果,但利用无人机多光谱影像开展作物氮素估测研究少有尝试。基于此,该文利用国家精准农业基地2017年夏玉米3个关键生育期无人机多光谱影像和田间实测叶片氮含量数据,开展夏玉米叶片氮素含量的无人机遥感估测研究。对该研究选用的15个光谱变量,通过相关性分析解析光谱变量与LNC的相关关系,筛选出对玉米叶片氮素含量敏感的光谱变量;应用后向逐步回归方法分析不同变量指数下估测精度变化,最终确定不同生育期夏玉米LNC估测的光谱变量,实现对夏玉米叶片氮含量的较高精度监测。研究发现:1)在3个生育时期,GRE和GNDVI与LNC都有很强的相关性,表明绿波段可以很好地进行夏玉米生物理化参数的反演;2)在喇叭口期和灌浆期,OSAVI、SAVI与LNC具有高度相关性,证明在夏玉米生长前期和后期选择控制土壤因素的光谱变量可以提高对氮素估测的能力。在筛选最优光谱变量建模过程中发现,喇叭口期选取5个光谱变量(GNDVI、GRE、OSAVI、REG、SAVI)建模效果最好,估测模型的R~2、RMSE和nRMSE分别为0.63、27.63%、11.62%;抽雄吐丝期选取6个光谱变量(REG、GRE、GNDVI、MNLI、RED、NDVI)建模效果最好,估测模型的R~2、RMSE和n RMSE分别为0.64、20.50%、7.80%;灌浆期选取5个光谱变量(GRE、GNDVI、RED、NDVI、OSAVI)建模效果最好,估测模型的R~2、RMSE和n RMSE分别为0.56、31.12%、12.71%;在不同生育期选取最优光谱变量进行夏玉米LNC估测具有很好的效果。应用无人机多光谱遥感影像数据可以很好地监测田块尺度夏玉米LNC的空间分布,可为玉米田间氮素精准管理提供空间决策服务信息支持。 展开更多
关键词 无人机 遥感 多光谱 叶片氮含量 逐步回归 夏玉米
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施氮量对小麦旗叶光合特性、SPAD值、籽粒产量及碳氮代谢的影响 预览
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作者 葛君 姜晓君 《天津农业科学》 CAS 2019年第3期1-4,共4页
为探讨氮素对小麦生长、产量及品质的最佳效应,以周麦22为试材,设置0,105,175,245,315kg·hm^-25个氮素水平,研究不同氮素用量对小麦旗叶光合特性、叶绿素含量(SPAD值)、施氮量与SPAD值相关关系、碳氮代谢相关酶活性、籽粒产量和蛋... 为探讨氮素对小麦生长、产量及品质的最佳效应,以周麦22为试材,设置0,105,175,245,315kg·hm^-25个氮素水平,研究不同氮素用量对小麦旗叶光合特性、叶绿素含量(SPAD值)、施氮量与SPAD值相关关系、碳氮代谢相关酶活性、籽粒产量和蛋白质含量的影响。结果表明:不同氮素用量对小麦光合特性、SPAD值、碳氮代谢相关酶活性、籽粒产量和蛋白质含量影响显著。在0~245kg·hm^-2范围内,光合速率、SPAD值随氮素用量的增加而增加,至245kg·hm^-2时值最大,较对照分别增加142.51%和3.05%,与对照差异极显著(P<0.01);315kg·hm^-2时上述指标均下降。蒸腾速率和气孔导度变化规律一致,在N175时值最大,较对照分别提高了165.91%和89.16%。处理间胞间CO2浓度与光合速率呈负相关关系。拔节期SPAD值与氮素用量具有显著正相关关系,决定系数为0.816,相关系数为0.783。籽粒产量和磷酸蔗糖合成酶活性随氮素用量的增加表现为先升高后降低的单峰变化规律,在245kg·hm^-2时值最大,较对照分别增加了28.19%和31.71%,与对照差异极显著(P<0.01);籽粒蛋白质含量与硝酸还原酶含量变化规律类似,均随氮素用量的增加而提高,至315kg·hm^-2时值最大。但综合光合速率、SPAD值、产量和品质等指标,以245kg·hm^-2作为周麦22在豫东地区的最佳氮肥用量。 展开更多
关键词 氮素 光合特性 SPAD值 产量 碳氮代谢
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Timing and splitting of nitrogen fertilizer supply to increase crop yield and efficiency of nitrogen utilization in a wheat–peanut relay intercropping system in China 预览
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作者 Zhaoxin Liu Fang Gao +9 位作者 Yan Liu Jianqun Yang Xiaoyu Zhen Xinxin Li Ying Li Jihao Zhao Jinrong Li Bichang Qian Dongqing Yang Xiangdong Li 《作物学报:英文版》 CAS CSCD 2019年第1期101-112,共12页
Agronomically optimizing the timing and rates of nitrogen(N) fertilizer application can increase crop yield and decrease N loss to the environment. Wheat(Triticum aestivum L.)–peanut(Arachis hypogaea L.) relay interc... Agronomically optimizing the timing and rates of nitrogen(N) fertilizer application can increase crop yield and decrease N loss to the environment. Wheat(Triticum aestivum L.)–peanut(Arachis hypogaea L.) relay intercropping systems are a mainstay of economic and food security in China. We performed a field experiment to investigate the effects of N fertilizer on N recovery efficiency, crop yield, and N loss rate in wheat–peanut relay intercropping systems in the Huang-Huai-Hai Plain, China during 2015–2017. The N was applied on the day before sowing, the jointing stage(G30) or the booting stage(G40) of winter wheat, and the anthesis stage(R1) of peanut in the following percentage splits: 50-50-0-0(N1), 35-35-0-30(N2), and 35-0-35-30(N3), using 300 kg N ha-1, with 0 kg N ha-1(N0) as control. 15N-labeled(20.14 atom %) urea was used to trace the fate of N in microplots. The yields of wheat and peanut increased by 12.4% and 15.4% under the N2 and N3 treatments, relative to those under the N1 treatment. The 15N recovery efficiencies( 15NRE) were 64.9% and 58.1% for treatments N2 and N3, significantly greater than that for the N1 treatment(45.3%). The potential N loss rates for the treatments N2 and N3 were23.7% and 7.0%, significantly lower than that for treatment N1(30.1%). Withholding N supply until the booting stage(N3) did not reduce the wheat grain yield; however, it increased the N content derived from 15N-labeled urea in peanuts, promoted the distribution of 15N to pods, and ultimately increased pod yields in comparison with those obtained by topdressing N at jointing stage(N2). In comparison with N2, the N uptake and N recovery efficiency(NRE) of N3 was increased by 12.0% and 24.1%,respectively, while the apparent N loss decreased by 16.7%. In conclusion, applying N fertilizer with three splits and delaying topdressing fertilization until G40 of winter wheat increased total grain yields and NRE and reduced N loss. This practice could be an environment-friendly N management strategy for wheat–peanut rel 展开更多
关键词 NITROGEN management Wheat–peanut RELAY INTERCROPPING system Crop yield NITROGEN recovery EFFICIENCY Apparent N loss
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Thermodynamic study on welding wire design of high nitrogen austenitic stainless steel 预览
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作者 明珠 王克鸿 +2 位作者 屈天鹏 王伟 冯胜强 《中国焊接:英文版》 EI CAS 2019年第1期49-55,共7页
Based on thermodynamic calculations, the effect of pressure and alloying elements on the nitrogen content, solidification mode, and welding characteristics were investigated in this study. By increasing the partial pr... Based on thermodynamic calculations, the effect of pressure and alloying elements on the nitrogen content, solidification mode, and welding characteristics were investigated in this study. By increasing the partial pressure of N 2 , the nitrogen content in the weld pool increased dramatically, and the γ zone was enlarged. The nitrogen content increased as alloying elements such as Cr and Mn were added to the molten steel. The δ zone with high temperature treatment was compressed by adding Ni. These alloying elements play important roles in the formation of the single γ region at the temperature of 298 K. With proper Mn addition, the phase area of γ was extended and became more stable, and the “ferrite trap” was also avoided. Two kinds of welding wires with different nitrogen contents were developed and corresponding MIG welding experiments were performed. As the nitrogen content in wire was higher than that in the base metal, severe blowhole defects and mixture microstructure of δ and γ developed. 展开更多
关键词 high NITROGEN steel NITROGEN LOSS THERMODYNAMICS CALCULATION WIRE DESIGN
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Review on photocatalytic and electrocatalytic artificial nitrogen fixation for ammonia synthesis at mild conditions: Advances,challenges and perspectives
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作者 Xiaolan Xue Renpeng Chen +5 位作者 Changzeng Yan Peiyang Zhao Yi Hu Wenjun Zhang Songyuan Yang Zhong Jin 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第6期1229-1249,共21页
The ammonia synthesis from nitrogen and water under ambient conditions is one of the most inviting but challenging reaction routes.Although nitrogen is abundant in the atmosphere and the ammonia synthesis reaction is ... The ammonia synthesis from nitrogen and water under ambient conditions is one of the most inviting but challenging reaction routes.Although nitrogen is abundant in the atmosphere and the ammonia synthesis reaction is exothermic on the thermodynamics,the conversion of N2 to ammonia is actually hard to proceed owing to the chemical inertness and stability of N2 molecules.In industry,ammonia synthesis is carried out by the Haber-Bosch process under harsh conditions (300-500 ℃,20-30 MPa) associated with the requirement of substantial energy input and the enormous emission of greenhouse gases (e.g.,CO2).Recently,a growing number of studies on photo(electro)catalytic and electrocatalytic nitrogen reduction reaction (NRR) in aqueous solution have attracted extensive attention,which holds great promise for nitrogen fixation under room temperature and atmospheric pressure.However,the very low efficiency and ambiguous mechanism still remain as the major hurdles for the development of photochemical and electrochemical NRR systems.Here we provide an overview of the latest progresses,remaining challenges and future prospects in photocatalytic and electrocatalytic nitrogen fixation.Moreover,this review offers a helpful guidance for the reasonable design of photocatalysts and electrocatalysts towards NRR by combining theory predictions and experiment results.We hope this review can stimulate more research interests in the relatively understudied but highly promising research field of NRR. 展开更多
关键词 heterogeneous CATALYSIS NITROGEN FIXATION AMMONIA synthesis PHOTOCATALYTIC ELECTROCATALYTIC NITROGEN reduction
水稻秸秆还田年限对稻麦轮作田土壤碳氮固存的影响 预览
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作者 崔思远 朱新开 +3 位作者 张莀茜 曹光乔 陈新华 沈有柏 《农业工程学报》 EI CAS CSCD 北大核心 2019年第7期115-121,共7页
为明确连续秸秆还田对农田土壤碳氮固存的影响,该文于扬州大学试验场展开研究。田间试验布置于2010年,设置秸秆不还田(NR),秸秆还田1a(SR1),秸秆还田2a(SR2),秸秆还田3a(SR3),秸秆还田4a(SR4),秸秆还田5a(SR5),秸秆还田6a(SR6),秸秆还田... 为明确连续秸秆还田对农田土壤碳氮固存的影响,该文于扬州大学试验场展开研究。田间试验布置于2010年,设置秸秆不还田(NR),秸秆还田1a(SR1),秸秆还田2a(SR2),秸秆还田3a(SR3),秸秆还田4a(SR4),秸秆还田5a(SR5),秸秆还田6a(SR6),秸秆还田7a(SR7),秸秆还田8a(SR8)9个处理。于2018年小麦收获后取样,测定分析了土壤容重、有机碳和全氮含量,计算碳氮比、层化率、土壤有机碳和全氮储量(等质量法)。结果表明,随着秸秆还田年限的增加,各土层有机碳和全氮含量逐渐提高,但增幅逐渐减小。0~5cm土层土壤碳氮比在短期内(≤3a)随着秸秆还田年限增加而显著提高,但是对其他土层和年限的无显著影响。随着秸秆还田年限增加,表层0~5cm与其他层次有机碳和碳氮比层化率先增长后下降,全氮层化率则先下降后上升。秸秆还田处理0~20cm土壤有机碳和全氮储量分别较NR提高6.23%~27.85%和6.04%~25.66%,各土层碳氮储量均随着秸秆还田年限的增加而提高,但是当还田年限>6a其增幅明显降低。综上所述,秸秆还田具有良好的碳氮固存效应,但是当秸秆还田年限>6a,土壤碳氮固存量的增幅明显降低,可适当减少还田量。 展开更多
关键词 土壤 有机碳 碳氮比 层化率 有机碳储量 全氮储量
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开花期短期缺氮处理提高黄瓜维生素C含量的机理研究 预览
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作者 李云云 李强 +3 位作者 柴琳 刘鹏 余宏军 蒋卫杰 《农业工程学报》 EI CAS CSCD 北大核心 2019年第5期134-140,共7页
AsA,也被称为维生素C,是植物中丰富的抗氧化剂。已有研究发现,在短期缺氮处理下,黄瓜中AsA含量提高。但是具体的调控机制并不明确。该研究中,以开花结果期的水培黄瓜植株为研究对象,分别探究短期缺氮处理对黄瓜果实和叶片中H2O2,MDA,As... AsA,也被称为维生素C,是植物中丰富的抗氧化剂。已有研究发现,在短期缺氮处理下,黄瓜中AsA含量提高。但是具体的调控机制并不明确。该研究中,以开花结果期的水培黄瓜植株为研究对象,分别探究短期缺氮处理对黄瓜果实和叶片中H2O2,MDA,AsA含量的影响,以及相关酶活性和AsA-GSH相关基因表达量的影响,据此研究短期缺氮条件下黄瓜AsA含量提高的机理。结果表明:与对照相比,在短期缺氮处理下,第7天果实中MDA和H2O2分别增加了1倍和0.8倍;处理1(T1,开花期营养液中无氮)果实中SOD酶活性,POD酶活性和CAT酶活性在第7天分别增加了60%,21%和74%;在处理第5天,果实和叶片中的T-AsA含量分别增加了70%和17%。短期缺氮处理下,T1叶片中APX-1,APX-3,APX-4,APX-5,AO-4,GR-1和GR-2等基因的表达水平在第1天显着上调;在T1果实中,AO-1,MDHAR-1,MDAHR-3,GR-2和APX-5等基因的的转录表达在第1天高于对照。T1果实中APX活性在第5天增加了51.6%;处理1叶片和果实中MDHAR酶活性在第3天分别增加了59.6%和24.8%;处理1果实中DHAR活性在第3天增加了109%。由此可知,花期短期的缺氮处理促进了黄瓜果实和叶片中T-AsA的积累和AsA-GSH循环途径相关酶活性的提高,同时AsA-GSH循环途径中的部分基因表达量上调。 展开更多
关键词 机理 基因表达 抗坏血酸 短期缺氮处理 黄瓜 AsA-GSH循环
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作物氮素快速营养诊断及其在甜菜上的应用前景 预览
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作者 梁晓慧 史树德 《北方农业学报》 2019年第1期49-56,共8页
文章从传统诊断和无损诊断两方面概括总结了几种常用的氮素营养诊断方法的优缺点,重点阐述了数字图像处理技术在作物氮素营养诊断方面的发展状况及其在甜菜生产上的应用前景,旨在为实现甜菜生产过程中氮素高效管理和准确施肥提供理论依据。
关键词 氮素 无损诊断 甜菜
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