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1.
为开发更温和与简便的高纯度植物多糖新型酶法水解提取工艺,该研究以胃蛋白酶（内肽酶）和曲蛋白酶（端肽酶）作为复合酶,建立酶解过程的动力学模型。对上述工艺所提取制备的多糖与45 ℃水提法、90 ℃水提法、胃蛋白酶提取法所制得的莲子多糖进行营养成分分析与结构（单糖组成、红外光谱、热特性、低场核磁和动态热机械）表征。结果显示,单酶（胃蛋白酶）/双酶分段酶解的动力学模型分别为：DH=2.101ln[1+(0.6133(E0/S0)+0.1441)t]和D''H-DH1=2.439ln[1+(3.923(E0/S0)+1.1756)t];双酶法提取的莲子多糖中多酚浓度（（0.42±0.008）mg/mL）和糖醛酸含量（15.65%±0.98%）最高,而以双酶法制得的莲子多糖蛋白质含量（0.73%±0.24%）最低;4种莲子多糖均含有葡萄糖 (Glc)、阿拉伯糖（Arab）、甘露糖（Man）和鼠李糖（Rha）,其中双酶法提取的多糖中半乳糖醛酸（Gal-UA）和Man的含量较多,分别为10.700%和10.752%;4种多糖均为α-型吡喃糖;双酶提取法相比水提法可有效降低莲子多糖中的蛋白质含量和玻璃化温度,提高结合水含量和亲水能力。酶解动力学模型可为莲子多糖纯化机制提供有效参考,尤其是双酶分段酶解法的特异性强、步骤简便,有利于提取和纯化莲子多糖成分,该研究可为动植物非淀粉类多糖的高质量提取和工业化生产提供理论基础。 相似文献
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为解决复杂猪舍环境下猪只堆叠和粘连导致群养猪只攻击行为识别准确率低和有效性差的问题，该研究提出一种改进的YOLOX模型，引入攻击活动比例（PAA）和攻击行为比例（PAB）2个优化指标，对群养猪只的撞击、咬耳和咬尾等典型攻击行为进行识别。首先，为提高模型特征提取能力添加归一化注意力模块获取YOLOX颈部的全局信息；其次，将YOLOX中的IoU损失函数替换为GIoU损失函数，以提升识别精度；最后，为保证模型的实时性将空间金字塔池化结构SPP轻量化为SPPF，增强检测效率。试验结果表明，改进的YOLOX模型平均精度达97.57%，比YOLOX模型提高6.8个百分点。此外，当PAA和PAB阈值分别为0.2和0.4时，识别准确率达98.55%，有效解决因猪只攻击行为动作连续导致单帧图像行为识别可信度低的问题。研究结果表明，改进的YOLOX模型融合PAA和PAB能够实现高精度的猪只攻击行为识别，为群养生猪智能化监测提供有效参考和技术支持。 相似文献
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短期干旱胁迫下棉花气孔表现及光合特征研究 总被引：3，自引：0，他引：3
研究气孔对干旱胁迫的响应有助于了解气孔调节真实行为和提高水分利用效率。本研究以‘国欣9号’为供试棉花品种,在人工气候室利用营养液培养,设置加入PEG-6000浓度为0（对照）、1.5%、3.0%和4.5% 4个处理,处理后1~7 d每隔1 d连续测定其气孔形态、光合和叶绿素荧光指标。结果表明：加入PEG-6000 1 d后,随着处理进程的延长,棉花叶片水势、气孔长度、宽度和开度、净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、胞间CO2浓度（Ci）、最大光化学效率（Fv/Fm）和实际光化学量子产量（Yield）均呈下降趋势,气孔密度和非光化学淬灭系数（NPQ）呈上升趋势;不同处理之间,随着干旱胁迫程度增加,也表现出相似趋势。处理后5 d和7 d,与正常处理相比,1.5%、3.0%和4.5%处理棉花气孔长度、宽度、水势、Pn、Gs、Tr和Ci均差异显著（P<0.05）,气孔长度降低幅度最小（1.17%~2.61%）,Gs降低幅度最大（61.62%~69.09%）,Tr降低幅度为37.62%~67.48%。相关分析表明,棉花气孔长度、宽度和开度之间极显著正相关（P<0.01）,气孔宽度和气孔密度不相关。气孔长度、宽度和开度与Pn和Yield极显著正相关（P<0.01）,与NPQ极显著负相关（P<0.01）,与Gs、Tr和Fv/Fm相关不显著。综上,棉花在PEG-6000诱发干旱后,通过降低气孔开度和增大气孔密度降低净光合速率和气孔导度,叶绿素荧光指标Yield和NPQ比Fv/Fm对干旱更敏感。 相似文献
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农业景观组成对玉米螟天敌数量的影响 总被引：1，自引：0，他引：1
高比例和多样的非耕作生境带来的农田景观高异质性是维持农业生物多样性的关键,推测提高非耕作生境组成能够促进农田中玉米螟天敌数量和种类增加。为揭示不同非耕作生境组成对玉米螟天敌数量的影响,本文选取东北平原玉米种植典型县——辽宁省昌图县,按照5个非耕作生境比例（0~10%、10%~20%、20%~30%、30%~40%和40%~50%）选取20个直径为600 m的样区。陷阱法采集玉米螟天敌,并用体视显微镜鉴别到科。主成分分析法筛选主要非耕作生境类型,逐步回归模型对非耕作生境组成（比例和类型）与玉米螟天敌数量进行拟合。并采用"赤池信息准则（AIC）"模型筛选,评估不同非耕作生境组成对玉米螟天敌数量的影响。研究结果表明,随着非耕作生境比例增加,玉米螟天敌数量呈先增后减的趋势,非耕作生境比例为20%~30%时天敌数量达最大值。非耕作生境比例20%~30%时,非耕作生境组成与玉米螟天敌数量关系最优模型（AIC=4.24,为最小值）是Y=b0-b1D+b2PC2,最优模型表明PC2（β=3.787,P=0.005）代表以林地为主的非耕作生境组成与玉米螟天敌数量呈显著正相关,景观多样性指数D（β=-3.173,P=0.005）与玉米螟天敌数量呈显著负相关。该比例的非耕作生境组成与玉米螟天敌数量关系的其他模型表明,以草地和村落为主（PC1）的非耕作生境与玉米螟天敌呈显著正相关（β=1.957,P=0.000）。而其他比例下,所有关系模型说明农田周边林地生境和其他作物耕地有利于提高农田中天敌数量。最适宜玉米螟天敌聚集的非耕作生境比例为20%~30%,以林地为主或村落、草地为主的非耕作生境,以及分布有其他作物的耕作生境能够提高玉米螟天敌数量。研究结果可为今后从景观生态角度构建适宜非耕作生境组成来防治玉米螟提供理论依据和方法。 相似文献
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不同供氮水平下玉米大豆间作体系干物质积累和氮素吸收动态模拟 总被引：2，自引：0，他引：2
玉米/大豆间作具有一定的养分利用优势,但是不同供氮水平对玉米/大豆间作体系干物质累积和氮素吸收的调控作用不同。本试验采用田间裂区设计,运用Logistic模型分析,模拟了4个氮水平下玉米/大豆间作作物干物质积累和氮素吸收的动态变化。结果表明,玉米、大豆干物质累积和氮素吸收动态符合Logistic模型,相关系数R2均在0.9以上。在N0（不施氮肥）、N1（180 kg·hm-2）、N2（240 kg·hm-2）和N3（300 kg·hm-2）供氮水平时,间作玉米最大生长速率（Imax-B）分别比单作提高34.2%、46.7%、25.9%和25.1%,而相应的供氮水平下,大豆的Imax-B分别降低27.7%、30.3%、16.5%和23.7%,但整个间作系统的Imax-B平均增加32.1%;玉米和大豆干物质的其他模拟参数与Imax-B规律一致。氮素吸收动态与干物质积累表现出同步的变化特点,在N1水平下,单位面积间作玉米的氮素最大吸收量（K-N）、最大吸收速率（Imax-N）和瞬时吸收速率（r-N）比相应单作分别提高18.4%、48.9%和25.8%,而间作大豆的K-N、Imax-N和r-N值比单作处理分别降低15.9%、29.9%和16.69%,整个间作系统氮素分别提高0.4%、13.7%和7.8%;施氮水平对大豆r-N无显著性影响。间作显著地提高了氮素当量比（LERN>1）,其中N0水平下LERN值最高,随着施氮量的增加,LERN有下降趋势。在本试验条件下,N2供氮水平下玉米/大豆间作体系干物质积累量和氮素吸收量最高,间作优势最明显。 相似文献
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以甘肃白银某污灌区重金属污染农田土壤为研究对象，对影响高精度便携式X荧光光谱（HDXRF）法总镉（CdT）测定精度的主要因素进行了筛选，分别研究了土壤水分、有机质类型与含量、土壤类型对HDXRF法CdT测定的影响，并采用相对误差（RE）、相对标准偏差（RSD）和决定系数（R2）对测定结果的准确度和精密度进行了评价。结果表明：HDXRF法CdT测定的RE≤10%、RSD≤10%、R2>0.99，符合农田土壤环境质量监测技术规范和美国环境保护署标准的准确度和精密度规定。HDXRF法CdT测定结果随着土壤水分含量的增加呈指数衰减趋势，衰减方程为y=0.803e–1.3284x，衰减系数（μω）为–1.328 4，R2为0.984 5。HDXRF法CdT测定结果与有机质含量呈显著的负相关关系（r=–0.955），且腐殖酸（HA）比泥炭（Peat）对测定结果的影响更大，HA与测定结果的校正方程为y=–1.555x +0.780，R2为0.934 4。土壤类型对HDXRF法CdT测定结果存在一定的影响，相对于红壤和水稻土，灰钙土的测定结果与传统实验室分析方法测定结果更接近。总之，虽然HDXRF法CdT测定结果受多种因素影响，但通过校正模型校正，其校正结果的可靠性能够满足Cd污染农田土壤精准调查需求。 相似文献
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不同雨强条件下工程措施对坡地产流产沙影响 总被引：4，自引：1，他引：4
基于试验站不同坡地措施（坡耕地和坡改梯）2016年和2017年的逐日降水、产流产沙数据，研究不同坡地措施和雨强下产流产沙规律特征，定量揭示坡改梯和坡耕地对产流产沙的影响。结果表明：（1）7月平均雨强I、最大雨强I30及坡地产流量最大，8月最大雨强I60与坡地产沙量最大，表明坡地产流产沙高峰期与雨强高峰期一致。（2）春夏两季产流、产沙量与I、I30和I60相关性显著（超过95%置信度检验）。其中坡耕地产流产沙量与I、I30、I60的相关系数整体高于坡改梯。春夏季坡耕地产沙量分别是坡改梯的3.91，7.85倍。（3）降雨主要集中在I（1~3 mm/h）、I30（3~29 mm/h）、I60（2~27 mm/h）之间，且坡地产流产沙量与最大雨强I30、最大雨强I60在95%置信度水平呈现显著正相关。当I30达到29.0 mm/h、I60达到26.6 mm/h时，坡地产流产沙达到最大，坡耕地产流产沙峰值是坡改梯的2.43，7.52倍以上，并且坡耕地全年产流产沙变异系数总体高于坡改梯，因此坡改梯工程在一定程度上防治了水土流失，使产流产沙变化减小。 相似文献
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为探讨磁化水灌溉处理在促进植物生长、提高植株重金属耐受性方面的作用机制,本研究采用随机区组试验设计,研究了镉胁迫（0 μmol·L-1、50 μmol·L-1、100 μmol·L-1）下磁化水灌溉处理对1 a生欧美杨''I-107''光合特性、叶绿素荧光动力学参数及生长特性的影响。结果表明：1）镉胁迫会显著降低植株高生长和根茎叶干物质量;低浓度（50 μmol·L-1）镉处理促进根系直径及体积增大（P<0.05）,高浓度（100 μmol·L-1）则会抑制根系各形态参数;镉胁迫下欧美杨叶绿素b和类胡萝卜素含量分别降低12.50%、43.24%和19.27%、46.37%（P<0.05）,净光合速率（Pn）、蒸腾速率（Tr）、胞间二氧化碳（Ci）分别降低13.68%和33.68%、8.07%和27.81%、5.00%和14.99%（P<0.05）,同时,PSⅡ潜在活性（Fv/Fm）、最大光化学速率（Fv/Fo）、光合性能指数（PIabs）和量子产额（φEo）均有不同程度降低。2）磁化水灌溉提高镉胁迫植株高生长及根茎叶干物质量,增加植株根系长度及表面积;同时,叶绿素a、叶绿素b和类胡萝卜素含量在0 μmol·L-1和100 μmol·L-1镉胁迫下分别提高16.99%、40.20%,8.67%、39.10%和17.32%、50.52%（P<0.05）;Gs、Ci及WUE显著升高,Tr则降低24.20%、23.33%、12.06%（P<0.05）;另外,Fv/Fm、Fv/Fo、PIabs显著升高（P<0.05）。综上所述,磁化水灌溉处理有助于提高镉胁迫下欧美杨幼苗光合色素含量,维持光合机构功能,增强光合碳同化速率,减轻镉胁迫对植株生长发育的抑制。 相似文献
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土壤饱和导水率（Ks）是反映土壤入渗性能与土壤持水能力的重要参数，为探究流域尺度下土壤Ks的空间分布特征及影响因素，更好地掌握土壤水文过程与调节机理，选取晋西北黄土丘陵区朱家川流域横向梯度（上游、中游、下游）不同土地利用方式下的土壤（70个样点）为研究对象，采用定水头法测定土壤Ks，并获取样点地形因子和其他土壤理化性质，通过建立土壤Ks偏最小二乘回归模型（PLSR），分析影响土壤Ks空间分布格局的主要因素。结果表明：（1）除土壤容重和砂粒含量为弱变异外，区域土壤理化性质其余因子均为中等变异；土壤Ks在横向梯度下表现为上游 > 中游 > 下游；（2）不同土地利用方式下土壤Ks差异显著（P<0.05），由高到低顺序为林地 > 农地 > 草地；（3）林地（VIP=1.997）与草地（VIP=1.710）利用方式、土壤容重（VIP=1.548）、土壤有机质（VIP=1.323）、大团聚体（VIP=1.266）、粉粒含量（VIP=1.062）和黏粒含量（VIP=1.049）是土壤Ks变化的主要因素，林地利用方式影响程度最大。土地利用、土壤性质、地形因子均是影响黄土丘陵区土壤Ks空间分布的主要因素，是用来模拟预测土壤Ks空间分布的重要因子。 相似文献
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甘肃省淤地坝工程的溃坝风险评价模型 总被引：2，自引：2，他引：0
[目的] 运用淤地坝工程溃坝风险评价模型,确定淤地坝工程发生溃决可能性的大小,为淤地坝运行管理提供技术支撑。[方法] 通过调研和对溃坝风险问题的梳理,形成淤地坝工程溃坝风险评价指标体系,运用层次分析法确定指标权重,构建了甘肃省淤地坝工程溃坝风险评价模型。[结果] 该模型包含水文风险（B1）、运行风险（B2）、管理风险（B3）、工程风险（B4）4个风险类型模块（其权重分别为0.12,0.13,0.12,0.63）及其下的16个具体评价指标;水面/泥面距拦泥坝高的距离（D1）、剩余淤积库容（D4）、有无3个管理负责人（D7）、坝体变形（D12）分别是4个风险类型模块的最大权重评价指标;对各指标的评分标准作了规定,依据综合风险得分将输出的风险等级和预警等级各划分为3级。[结论] 淤地坝工程溃坝风险评价模型由输入、分析和输出3个模块组成,层次清晰,架构明确。评估模型的构建可对汛期淤地坝工程风险的评价提供实时预警数据。 相似文献
11.
【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。 相似文献
12.
Kyle Devey Michael Mucalo Gordon Rajendram Joseph Lane 《Communications in Soil Science and Plant Analysis》2015,46(4):72-80
Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing. 相似文献
13.
《中国生态农业学报》2014,(8)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
14.
Aleš Lebeda Ivana Doležalová Eva Křístková Barbora Mieslerová 《Genetic Resources and Crop Evolution》2001,48(2):153-164
Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions. 相似文献
15.
M.A. Callaham Jr. J.M. BlairT.C. Todd D.J. KitchenM.R. Whiles 《Soil biology & biochemistry》2003,35(8):1079-1093
The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils. 相似文献
16.
Thomas Larsen Jesper Luxhøi Jakob Magid Lars Stoumann Jensen Paul Henning Krogh 《Biology and Fertility of Soils》2007,44(1):59-68
We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization
and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition
with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the
decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots
with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass,
soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration,
N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially
(<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation
in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils,
indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but
the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation
for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community
performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea. 相似文献
17.
《中国生态农业学报》2014,(7)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
18.
《中国生态农业学报》2014,(6)
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology, 相似文献
19.
Grete Skrede Berit Karoline Martinsen Anne-Berit Wold Stein-Erik Birkeland Kjersti Aaby 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):193-208
Abstract A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species. 相似文献
20.
《Communications in Soil Science and Plant Analysis》2012,43(7):865-877
Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L?1 nitric acid (HNO3) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L?1 ammonium acetate (NH4OAc) and 1.0 mol L?1 HNO3 extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils. 相似文献