水钾耦合对苜蓿根颈抗氧化特性及越冬率的影响     

孙明雪  张玉霞  丛百明  夏全超  田永雷  张庆昕  张冬梅 《草地学报》2021,29(12):2845-2852

为探究不同水钾耦合处理对科尔沁沙地生境下种植苜蓿（Medicago sativa）抗寒生理特性的影响，以‘骑士T’和‘公农1号’苜蓿品种为试验材料，采用两因素裂区随机区组设计，水分处理为主区：灌水时间间隔分别为4 d，8 d和12 d（用W₁，W₂，W₃表示）；钾肥施用量水平为副区，具体施用量分别为50 kg·hm^-2 K₂O，100 kg·hm^-2 K₂O和150 kg·hm^-2K₂O（用K₁，K₂，K₃表示），并设置不施钾肥为对照（CK），于越冬前期挖取苜蓿根颈材料测定丙二醛（Malondialdehyde，MDA）、可溶性蛋白含量和抗氧化酶活性，翌年测定越冬率。结果表明：在W₃灌水时间间隔处理下，‘骑士T’和‘公农1号’品种苜蓿根颈的过氧化氢酶、过氧化物酶和超氧化物歧化酶活性、越冬率以及可溶性蛋白含量均明显高于W₁和W₂处理，其中以K₂施用量处理下的数值与CK差异最显著（P<0.05），且此施肥量下的MDA含量也显著低于CK（P<0.05）。因此在科尔沁沙地生境下生产苜蓿，灌水时间间隔为12 d、钾肥施用量在100 kg·hm^-2K₂O有利于提高苜蓿抗寒性。  相似文献   

黑龙江省国有林区脆弱异质性家庭对停伐政策的态度及影响因素研究     

杨博琳  王蕾  刘钰佳  李娇  赵宗胤 《安徽农业科学》2017,45(16)

基于2016年黑龙江省重点国有林区348户家庭的微观调查数据,实证分析黑龙江省国有林区脆弱异质性家庭对停伐政策的态度及影响因素。采用因子分析与综合评价法将348户职工家庭分为脆弱性家庭和非脆弱性家庭,描述性分析2组样本家庭对停伐政策的态度及认知情况,利用多元有序logit模型分析脆弱性与非脆弱性家庭对停伐政策态度的影响因素。结果表明:非脆弱性家庭对停伐政策的了解程度及执行情况的评价均高于脆弱性家庭,脆弱性家庭相对非脆弱性家庭对停伐政策的认可度较高,但是应对风险冲击的能力相对较低。脆弱性家庭和非脆弱性家庭对停伐政策的态度受户主特征、家庭特征以及政策认知特征变量的显著影响,但脆弱性家庭变量参数估计绝对值相对更大,因而停伐政策对脆弱性家庭有着更为敏感和强烈的冲击。  相似文献   

不同方法构建磺胺二甲氧嘧啶免疫抗原的比较研究   总被引：3，自引：0，他引：3  

曹盛丰  程美蓉  陈克强  刘永德  杨丽娥 《中国预防兽医学报》2004,26(4):301-303

为探讨合成磺胺二甲氧嘧啶(SDM)免疫抗原的有效途径,采用重氮偶合法和戊二醛法分别合成SDM免疫抗原,并对其结构特征、光谱特征和SDM结合比进行比较.结果表明,在合成SDM-BSA中采用重氮偶合法比戊二醛法好.  相似文献   

黄土低山丘陵及坨甸草原区风蚀规律的研究     

张启昌  徐程阳  魏献民  宋广智  赵宝华 《吉林林学院学报》1992,(2)

本文通过对黄土低山丘陵及坨甸草原区248个风蚀图斑资料的分析,运用线性模型理论,对此地区的风蚀规律进行了研究。获得了下垫面各因素与风蚀量关系的数学模型。找出了影响风蚀的主导因素,并系统阐述了植被覆盖度和土地利用类型对风蚀量大小的影响,且与水蚀规律进行了比较分析。  相似文献   

Spatio-temporal modelling of broad scale heterogeneity in soil moisture content: a basis for an ecologically meaningful classification of soil landscapes     

Gimona  Alessandro  Birnie  Richard V. 《Landscape Ecology》2002,17(1):27-41

We describe the classification of landscapes characterised bymineral soil using a model that calculates soil moisture availability on amonthly basis. Scotland is used as a case study area. The model uses potentialsoil moisture deficit, estimated using broad scale (40 × 40 km)climate patterns, in conjunction with meteorological station measurements toobtain finer scale values of climatic soil moisture deficit. Point estimates ofsoil available water are obtained for soil characteristics using appropriatepedotransfer functions, and geostatistical techniques are used to upscale theresults and interpolate to a 1-km grid. Known heterogeneityin soil physical characteristics is used to provide local corrections to thepotential soil moisture deficit, estimated using the climatic variables above.Temporal profiles of monthly water content are modelled for each1-km location and classified into six classes usingunsupervised cluster analysis. The spatial distribution of these classesreflects regional variations in the availability of moisture and energy, onwhich finer-grained topographic patterns are superimposed. In the case study,the broad scale spatial heterogeneity of heathlands and grasslands on mineralsoils in Scotland is shown to be strongly related to the soil moistureclassification. The results can be used in studies investigating the patternsofdistribution of communities at the landscape and regional scale.This revised version was published online in May 2005 with corrections to the Cover Date.  相似文献   

流固耦合方法对气携旋流分离的数值模拟     

李鑫  魏燕杰  李国一 《绿色科技》2015,(4):279-283

指出了气携式液液旋流器是港区小型化、船载化洗舱、压仓含油废水预处理的关键设备.采用流固耦合数值模拟方法再现压缩机进气、油水旋流与设备本体的整体气浮—旋流—分离耦合计算模型 ,对其核心部件微孔旋流套管的构型、孔径、内外压差及腔内流场分布进行了三维数值模拟 ,得到了微孔旋流腔内汽、水、油三相的流场分布 ,合理确定了注气腔气—水平衡分压、溢流比和微孔孔径 ,并模拟了压缩机、潜水泵正常工况下进气、进水、出水、油污溢流的流量、流速波动范围 ,为该设备的一体化构型设计和加工选材提供了参考数据.  相似文献   

水肥耦合对小麦/玉米带田产量及构成因素的影响   总被引：5，自引：0，他引：5  

杨蕊菊  马忠明 《西北农业学报》2015,24(1):54-59

采用"3414"最优回归设计方案,于2007-2008年在甘肃省农业科学院张掖节水试验站,开展不同水肥耦合处理小麦/玉米带田产量效应研究。结果表明,不同水肥耦合模式对小麦/玉米带田产量的影响较大,其差异达极显著水平。其中,氮肥对产量的贡献最大,水分次之,磷肥最小,氮肥对带田混合产量的绝对贡献率达79.4%,而水分对带田混合产量的绝对贡献率达为52.9%;水肥耦合效应为:水氮耦合水磷耦合氮磷耦合;获得高产量12 952.5~13 880.0kg/hm2的施氮量为420~630kg/hm2、灌水量为5 550~6 750m3/hm2、施磷量为120kg/hm2。相关分析表明,施氮量和灌水量与间作玉米的穗粒数、千粒质量、穗粒质量、株高均呈极显著正相关,施氮量与间作小麦的穗粒质量、穗粒数呈极显著正相关。  相似文献   

Performance of DSSAT-Nwheat across a wide range of current and future growing conditions     

《European Journal of Agronomy》2016

Crop models are widely used in agricultural impact studies. However, many studies have reported large uncertainties from single-model-based simulation analyses, suggesting the need for multi-model simulation capabilities. In this study, the APSIM-Nwheat model was integrated into the Decision Support System for Agro-technology (DSSAT), which already includes two wheat models, to create multi-model simulation capabilities for wheat cropping systems analysis. The new model in DSSAT (DSSAT-Nwheat) was evaluated using more than 1000 observations from field experiments of 65 treatments, which included a wide range of nitrogen fertilizer applications, water supply (irrigation and rainout shelter), planting dates, elevated atmospheric CO₂ concentrations, temperature variations, cultivars, and soil types in diverse climatic regions that represented the main wheat growing areas of the world.DSSAT-Nwheat reproduced the observed grain yields well with an overall root mean square deviation (RMSD) of 0.89 t/ha (13%). Nitrogen applications, water supply, and planting dates had large effects on observed biomass and grain yields, and the model reproduced these crop responses well. Crop total biomass and nitrogen uptake were reproduced well despite relatively poor simulations of observed leaf area measurements during the growing season. The low sensitivity of biomass simulations to poor simulations of leaf area index (LAI) were due to little changes in intercepted solar radiation at LAI >3 and water and nitrogen stress often limiting photosynthesis and growth rather than light interception at low LAI.The responses of DSSAT-Nwheat to temperature variations and elevated atmospheric CO₂ concentrations were close to observed responses. When compared with the two other DSSAT-wheat models (CERES and CROPSIM), these responses were similar, except for the responses to hot environments, due to different approaches in modeling heat stress effects.The comprehensive evaluation of the DSSAT-Nwheat model with field measurements, including a comparison with two other DSSAT-wheat models, created a multi-model simulation platform that allows the quantification of model uncertainties in wheat impact assessments.  相似文献   

几种利用乳中尿素氮浓度估测尿氮排泄量模型的评价     

李鹏 《中国奶牛》2011,(22):11-14

本文利用34组国内外报道的荷斯坦牛乳中尿素氮浓度和尿氮排泄量的实测数据，对目前提出的部分利用MUN估测尿氮排泄量的模型进行了比较。结果表明，Zhai（2005）提出的模型[UN（g/d）：10．1×MUN（mg／dL）＋47.3]预测效果较好（P〉0．05）。划分MUN浓度范围分别建立模型可能会提高预测的准确度。此外，根据34组数据做简单回归：UN（g/d）=12．78×MUN（mg/d1）＋28．15（n=34，R2=0．59）。  相似文献   

人居环境视角下居民垃圾分类意愿实证研究及政策建议——基于河南省郑州、洛阳、商丘和漯河四地市的调研     

李凤琴  韩灵梅  李静  王菲  王贞 《绿色科技》2021,(4)

基于河南省人居环境现状,分别对郑州、洛阳、商丘和漯河四地市进行了实地调研,通过建立二元Logistic模型,分析了影响居民垃圾分类意愿高低的因素。结果表明:文化程度、经济发展、政策支持对提高居民垃圾分类意愿具有较强的正相关影响,而居民人居环境满意度对提高垃圾分类意愿具有负相关影响;女性相比男性的垃圾分类意愿更高,城市居民相比农村居民的垃圾分类意愿更高。基于此结论,从政府和社会两个方面分别提出了相关建议,以供参考。  相似文献