Rice with fish culture in the semi-deep waters of the Mekong Delta, Vietnam: a socio-economical survey   总被引：1，自引：0，他引：1  

A J Rothuis  D K Nhan  C JJ Richter  F Ollevier 《Aquaculture Research》1998,29(1):47-57

The results of a socio-economical survey of farming systems practising rice culture with introduced fish, rice culture with indigenous fish and rice monoculture in the semi-deep waters of the Mekong Delta, Vietnam, are presented. Rice and fish yields, inputs, and cost-benefits were computed to evaluate the agricultural effects of rice with fish culture. Household size, labour availability and educational level were not significantly different among the three farming systems. Rice-fish farming systems differed mainly from rice monoculture by a higher fertilizer/ water requirement and less pesticide use. The total farm cash and net return did not differ among the farming systems. The main beneficial effects of rice-fish culture are thought to be related to environmental sustainability, system biodiversity, farm diversification and household nutrition.  相似文献   

地膜覆盖栽培对春小麦叶片衰老特性的影响   总被引：9，自引：3，他引：6  

牛俊义  李兴涛盖玥 王鹤龄 《麦类作物学报》2005,25(5):92-95

为了揭示春小麦在地膜栽培条件下是否早衰的问题,采用管栽模拟试验的方法,研究了地膜覆盖和露地栽培条件下春小麦叶片的叶绿素、蛋白质、叶片丙二醛(M DA)含量和细胞质膜相对透性的变化。结果表明,采用地膜覆盖栽培方法,在春小麦生长前期能明显提高叶片叶绿素和蛋白质的含量(日均增加量分别比露地春小麦高31.49%和7.94%),但后期又会加速其降解速率;M DA含量和细胞质膜相对透性均表现为覆膜处理高于露地处理(日均增加量分别比露地春小麦高71.96%~11.78%和2.42%~9.57%)。说明覆膜栽培可使春小麦提前进入正常衰老阶段,但由于其增温、保湿等效应,使春小麦生长量增加,穗粒数和穗粒重比露地春小麦提高22.95%和27.68%,表现出良好的增产效应。  相似文献   

Moderate stocking density does not influence the behavioural and physiological responses of rainbow trout (Oncorhynchus mykiss) in organic aquaculture     

Pierluigi Carbonara  Sbastien Alfonso  Francesco Gai  Laura Gasco  Giovanni Palmegiano  Maria Teresa Spedicato  Walter Zupa  Giuseppe Lembo 《Aquaculture Research》2020,51(7):3007-3016

Welfare in farmed fish got particular attention during the last decades from both governmental and public sides. In aquaculture context, welfare concerns are mainly related to handling procedures, water quality and stoking densities. In Europe, authorities had to clarify the threshold limits of stocking densities to maintain fish good welfare, including for organics aquaculture through the EC regulation 710/2009. However, effects of stocking density on fish welfare are complex and sometimes contradictory. Moreover, there is a lack of knowledge about the impact of density on fish welfare in organic aquaculture. Thus, the aim of the study is to asses welfare state of rainbow trout (Oncorhynchus mykiss) at two initial stocking densities (low density, LD: 12 kg/m³ and high density, HD: 17 kg/m³) fed using organic feed by combining the monitoring of growth performances, behaviour (swimming activity) and physiological indicators (i.e. cortisol, glucose, lactate, hematocrit, red blood cellule count and lysozyme). At the end of experiment, the stocking density reached 21 kg/m³ and 30 kg/m³ for the LD and HD respectively. Overall, growth performances, swimming activity and level of physiological indicators of stress and welfare were similar between HD and LD over the experiment duration. To conclude, we observed no alteration of fish welfare between the two stocking densities monitored. This study suggests that a final stocking density of 30 kg/m³ can be considered for organic aquaculture of rainbow trout respecting welfare.  相似文献   

我国主要动物源性寄生虫病检测技术研究进展   总被引：2，自引：0，他引：2  

盖文燕/王君玮/王娟/曲志娜  黄秀梅  李玉清  洪军 《中国动物检疫》2013,30(12):15-18

  相似文献   

消除水分因素影响的野外原状土壤盐分高光谱建模估测   总被引：4，自引：2，他引：2  

陈红艳  赵庚星  李玉环  李华  盖岳峰 《农业工程学报》2018,34(12):119-125

土壤水分被确定为土壤属性(有机碳、盐分等)光谱预测准确性下降的一个主要原因,该文通过两种方法的对比旨在探索去除土壤水分影响、提高盐分高光谱定量估测精度的方法和技术路线。首先以山东省东营市垦利区为研究区,采用地物光谱仪测定了96个样本的野外原状土和室内风干土光谱,并进行一阶导数变换;接着,对比分析盐分光谱特征及水分的影响;然后分别采用外部参数正交化(external parameter orthogonalization,EPO)和非负矩阵分解(non-negative matrix factorizing,NMF)方法校正和融合野外原状土光谱,去除土壤水分因素的影响,形成野外原状土光谱的校正和融合光谱;最后基于野外原状土光谱、校正和融合光谱,分别采用多元逐步线性回归(multiple step linear regression,MSLR)和偏最小二乘回归(partial least squares regression,PLSR)构建土壤盐分含量的估测模型,并进行验证和比较,分析预测精度变化。结果显示:土壤水分对野外原状土光谱及盐分光谱特征影响较大,需要研究去除;EPO和NMF均可提高土壤盐分野外原位光谱估测精度,比较而言,NMF效果更为显著;EPO结合PLSR或NMF结合MSLR可作为去除水分影响的土壤盐分校准模型的技术路线。  相似文献   

基于熵权物元模型的青海省土地生态安全评价   总被引：1，自引：0，他引：1  

马红莉  盖艾鸿 《中国农学通报》2014,30(2):208-214

为了科学评判生态脆弱区青海省土地资源的生态安全及其变化情况,运用熵权法和P-S-R模型,构建该区域土地生态安全评价指标体系及权重,采用物元理论建立土地生态安全的综合评判模型,并对青海省2000—2010年土地生态安全状况变化情况及空间差异进行了分析。结果表明：青海省土地生态安全的发展趋势大体表现为“较不安全→临界安全”;青海省各市（州、地区）的土地生态安全状况变化情况不尽相同,地区间差异明显;影响青海省土地生态安全水平的主要制约因素包括经济密度、人均耕地面积、林草覆盖率、水土协调度、成灾面积比重和化肥施用量。  相似文献   

Unilateral scrotal pyocele in ram caused by Staphylococcus capitis     

D Lacasta  LM Ferrer  JJ Ramos  A Ortín  AI Vela  MV Latre 《Australian veterinary journal》2009,87(12):484-486

A massive unilateral scrotal pyocele caused by Staphylococcus capitis in a 6‐year‐old ram is reported. Ultrasound examination of the right hemiscrotum showed an irregular hyperechoic mass in an anechoic fluid. A dense exudate was collected from the scrotum for microbiological analysis. Grossly, there was an extensive greenish purulent exudate and a completely atrophied right testis. Coagulase‐negative S. capitis was isolated in pure culture. To the authors' knowledge, this is the first report of genital infection by S. capitis in rams. This microorganism should be included in the differential diagnosis of ovine genital infections.  相似文献   

三峡库区土地利用与土壤质量演化的关系研究--以重庆万州为例   总被引：1，自引：0，他引：1       下载免费PDF全文

张洪  傅瓦利  袁红  王改改 《西南大学学报(自然科学版)》2006,28(2):240-243

在三峡库区有代表性的重庆万州地区选择4种典型利用方式,运用土壤质量演化指数法,研究土地利用方式对三峡库区土壤质量演化的影响。计算结果表明,旱地转变成其他利用方式后,土壤质量均向良性方向演化,而且果园改善最大,菜地次之,撂荒地也有所恢复。  相似文献   

稠油管输起始加热温度熵产最小优化设计     

盖平原 《油气储运》2011,30(7):501-503,472

基于熵产率最小化原理,分析了原油在输送过程中散热损失和摩擦阻力引起的熵产情况,优化了熵产率最小所对应的管输起始加热温度。研究结果表明:最小熵产率与输送流量、起始温度和管道管径有关,输量对熵产率有一定的影响,输量越高,输送单位质量原油的熵产率越低,但随输量的增加,熵产率降低的幅度逐渐减少;只有适当的起始加热温度才能保证单位质量原油输送单位距离所产生的熵产率最小;对应最小熵产率的原油起始温度随管径的增大而降低。最小熵产率优化设计方法克服了热经济设计方法需要材料价格、施工费用等参数难于准确选取和所得结果与当前物价及贷款利率有关的缺点。  相似文献   

油炸条件对鸡胸肉剪切力的影响     

李改  赵改名  李苗云  柳艳霞  黄现青  张秋会  郝玉娜 《江苏农业学报》2011,27(3)

将鸡胸肉在70℃、85℃、100℃、125℃、150℃、165℃和180℃的棕榈油中分别炸制3.0 min、4.5 min和6.0 min,分析其剪切力、可溶性含氮物和水分含量及感官指标的变化。结果表明：油炸使肉块色泽加深、风味增加,各项指标随油炸温度和油炸时间变化而改变;随着油炸温度升高,鸡肉的剪切力呈先上升后下降的趋势,而可溶性总氮和水分含量呈总体下降趋势;随着炸制时间延长,鸡肉的剪切力整体呈上升的趋势,而水分含量和可溶性总氮整体呈下降趋势。150℃油炸4.5 min或者165℃油炸3.0 min出品率较高;而180℃油炸3.0 min,则可溶性含氮物含量较高,质地较嫩。  相似文献