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The Impacts and Causes of Land Fragmentation on Farm Productivity: Case Review of East African Countries
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作者 Joseph Mayindo Mayele Jacob B. Kolleh Joel Emmanuel Saburi 《Open Journal of Ecology》 2024年第5期455-482,共28页
This report provides an overall assessment of land fragmentation problems in East Africa. Many parts of East Africa have become highly fragmented, putting development systems and activities in these areas at risk of c... This report provides an overall assessment of land fragmentation problems in East Africa. Many parts of East Africa have become highly fragmented, putting development systems and activities in these areas at risk of complete collapse. Land fragmentation occurs when land gets converted for agriculture, industrialization, or urbanization, invaded by non-local plants, or enclosed for individual use and by subdividing farmlands into subsequent smaller units called parcels with varying average farm sizes. Fragmentation results from inappropriate agricultural development processes and ineffective land use planning that fails to recognize how farmland is used, and the importance of its interconnected areas. Insecurity of tenure and resource rights are key factors in making this possible. Land fragmentation is one of the key reasons why the ability of most resources in East Africa becomes scarcer, and those remaining become “privatized” by more powerful community members—keen to maintain their access to them. Such individualistic attitudes are new and disadvantage the poorest even further by affecting the traditional customary safety nets and agricultural outputs. Neither the government nor customary governance systems effectively protect resource access for the poorest. This review summary report identifies the key causes, measures, and implications, government interventions, and the common remedies to land fragmentation problems in the East African Countries of Kenya, Uganda, Rwanda, and Tanzania including neighboring Ethiopia, and the Sudan. The findings indicated from 2005 to 2015, the population kept increasing for all the named countries in East Africa with Rwanda and Uganda having a substantial increase in population density. The study review further explores the trend in the performance of agriculture by average farm sizes within the intervals of five years by highlighting their strong linkages and found that the average farm size has declined drastically, especially for Kenya. This can only mean that small farms kept becoming smaller and smaller and that there were more small-scale farmers. The results further depicted that the major and commonly cultivated food crops among the East African countries include maize, sorghum, rice, cassava, sweet potatoes, bananas, Irish potatoes, beans, peas, etc., with maize yields (Mt/ha) in 2003 for Uganda being the highest (1.79 Mt/ha) and the lowest in Rwanda (0.77 Mt/ha) respectively. Therefore, from the review results, recommendations are being made as to how the negative impacts of land fragmentation on agricultural productivity can be reduced or mitigated. One way is by community sensitization and awareness about the importance of land consolidation and its proposition on farm productivity. 展开更多
关键词 Land Fragmentation Land Consolidation farm Productivity INDUSTRIALIZATION Impacts CAUSES Average farm Size population East Africa
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Stand Structure, Diversity and Regeneration Status of Woody Species in Open and Exclosed Dry Woodland Sites around <i>Molapo</i>Farming Areas of the Okavango Delta, Northeastern Botswana 被引量:2
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作者 John Neelo Demel Teketay +1 位作者 Keotshephile Kashe Wellington Masamba 《Open Journal of Forestry》 2015年第4期313-328,共16页
Stand structure, diversity and regeneration status of woody species were investigated in open and exclosed dry woodland sites in Island Safari, Shorobe and Xobe, northeastern Botswana. A total of 105, 111 and 130 quad... Stand structure, diversity and regeneration status of woody species were investigated in open and exclosed dry woodland sites in Island Safari, Shorobe and Xobe, northeastern Botswana. A total of 105, 111 and 130 quadrats, measuring 20 × 20 m each, were laid down along parallel line transects in the three sites, respectively, to collect data. A total of 47 species, representing 16 families and 24 genera, were recorded in the study sites. Of these, 33 species representing 13 families and 20 genera, 41 species representing 15 families and 23 genera and 27 species representing 10 families and 14 genera were encountered in Island Safari, Shorobe and Xobe, respectively. The most diverse family was Fabaceae followed by Combretaceae and Tiliaceae at all the three sites. The most diverse genus was Acacia, followed by Combretum and Grewia. The diversity of woody species in the study sites were 2.18, 2.15 and 1.5 in Shorobe, Island Safari and Xobe, respectively, while their corresponding evenness values were 0.6, 0.6 and 0.5, respectively. The mean densities of the woody species encountered in Island Safari, Shorobe and Xobe were 2629, 4271 and 2745 individuals ha&#451, respectively. The five densest species were Colophospermum mopane, Dichrostachys cinerea, Acacia tortilis, Philenoptera violacea and Terminalia prunioides in Island Safari, C. mopane, A. tortilis, A. erioloba, P. violacea and D. cinerea in Shorobe and Acacia mellifera, A. tortilis, P. nelsii, A. luederitzii and A. erubescens in Xobe. The highest important value index values were exhibited by C. mopane, D. cinerea, A. tortilis, P. violacea and T. prunioides in Island Safari, C. mopane, A. erioloba, A. tortilis, P. violacea and C. imberbe in Shorobe, and A. mellifera, A. tortilis, P. nelsii and A. luederitzii in Xobe. The alarming result was the fact that 71%, 80% and 85% of the woody species recorded in Island Safari, Shorobe and Xobe, respectively, exhibited hampered regeneration and, thus, unhealthy population structures. Therefore, there is an urgent need to address the observed unhealthy population structures of the woody species through investigation of the major causes of their hampered regeneration, and also designing measures that will facilitate natural and artificial regeneration of these species at the three study sites. 展开更多
关键词 Anthropogenic Disturbance Area EXCLOSURE Deforestation Density DIVERSITY Flood Recession (Molapo) farming Important Value Index population Structure REGENERATION
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Excessive 5-year weight gain predicts metabolic syndrome development in healthy middle-aged adults 被引量:1
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作者 Jong-Dar Chen Pau-Chung Chen 《World Journal of Diabetes》 SCIE CAS 2011年第1期8-15,共8页
AIM:To quantitatively examine the impacts of an easyto-measure parameter-weight gain-on metabolic syndrome development among middle-aged adults. METHODS:We conducted a five-year interval observational study.A total of... AIM:To quantitatively examine the impacts of an easyto-measure parameter-weight gain-on metabolic syndrome development among middle-aged adults. METHODS:We conducted a five-year interval observational study.A total of 1384 middle-aged adults not meeting metabolic syndrome(MetS)criteria at the initial screening were included in our analysis.Baseline data such as MetS-components and lifestyle factors were collected in 2002.Body weight and MetS-components were measured in both 2002 and 2007.Participants were classified according to proximal quartiles of weight gain(WG)in percentages(%WG≤1%,1%< %WG≤5%,5%<%WG≤10%and%WG>10%, defined as:control,mild-WG,moderate-WG and severe-WG groups,respectively)at the end of the follow-up. Multivariate models were used to assess the association between MetS outcome and excessive WG in the total population,as well as in both genders. RESULTS:In total,175(12.6%)participants fulfilled MetS criteria within five years.In comparison to the control group,mild-WG adults had an insignificant risk for MetS development while adults having moderate-WG had a 3.0-fold increased risk for progression to MetS [95%confidence interval(CI),1.8-5.1],and this risk was increased 5.4-fold(95%CI,3.0-9.7)in subjects having severe-WG.For females having moderate-and severe-WG,the risk for developing MetS was 3.6(95% CI,1.03-12.4)and 5.5(95%CI,1.4-21.4),respectively. For males having moderate-and severe-WG,the odds ratio for MetS outcome was respectively 3.0(95%CI, 1.6-5.5)and 5.2(95%CI,2.6-10.2). CONCLUSION:For early-middle-aged healthy adults with a five-year weight gain over 5%,the severity of weight gain is related to the risk for developing metabolic syndrome. 展开更多
关键词 EXCESS weight gain Metabolic syndrome middle-ageD adults FOLLOW-UP WORKER population
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Genetic Variation Dissection of Rice Blast Resistance Using an Indica Population 被引量:1
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作者 ZHANG Mengchen WEI Zhonghua +12 位作者 YUAN Xiaoping WANG Caihong WANG Shan NIU Xiaojun XU Xin XU Qun FENG Yue YU Hanyong WANG Yiping ZHU Zhiwei ZHAI Rongrong YANG Yaolong WEI Xinghua 《Rice science》 SCIE CSCD 2020年第4期255-258,共4页
Rice blast disease,caused by fungus pathogen Magnaporthe oryzae,is one of the most destructive diseases that impact rice farming.In the worldwide,rice harvests lose 10%to 30%of the total production because of blast in... Rice blast disease,caused by fungus pathogen Magnaporthe oryzae,is one of the most destructive diseases that impact rice farming.In the worldwide,rice harvests lose 10%to 30%of the total production because of blast infection,which is estimated to be enough for feeding 60 million people(Skamnioti and Gurr,2009). 展开更多
关键词 population enough farming
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Sensory Analyses and Nutritional Qualities of Hand-Made Breads with Organic Grown Wheat Bread Populations
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作者 Camille Vindras-Fouillet Olivier Ranke +3 位作者 Jean-Pierre Anglade Bruno Taupier-Letage Chable Véronique Isabelle Goldringer 《Food and Nutrition Sciences》 2014年第19期1860-1874,共15页
Population varieties can meet the needs of organic farming as they are composed of diverse genotypes and have nutritional and sensory characteristics of interest. Their intra-specific genetic variability helps to adap... Population varieties can meet the needs of organic farming as they are composed of diverse genotypes and have nutritional and sensory characteristics of interest. Their intra-specific genetic variability helps to adapt to the diversity of soil and climate conditions, management practices and needs. Moreover, an integrated organic bread sector has emerged willing to use more wheat populations. To explore sensory and nutritional potential of bread wheat populations, hedonic tests, sensory profile and nutritional analyses were implemented on eight wheat population varieties and one modern variety. Hedonic tests revealed consensus among consumer when ranking according to specific sensory characteristics and showed preferences for red wheat breads. Descriptive sensory test showed significant differences between genotypes on 6 out of 11 descriptors and confirmed the sensory specificity of red wheat accessions. Nutritional analyses showed differences especially on minerals content. Sensory differences between breads from different genotypes can be perceived both by trained and untrained panels as suggested by results. Moreover, red accessions showed specific sensory characteristics which are well-perceived by the two panels. Breeding effort should be maintained for high diverse genotypes with improved sensory and nutritional qualities adapted to organic farming conditions. Indicators like kernel colour should be sought to help integrate such criteria. 展开更多
关键词 ORGANIC farming SENSORY ANALYSIS BREAD Wheat population Varieties NUTRITIONAL ANALYSIS
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Do Birds Return to Agricultural Landscapes through Adoption of Natural Farming Practices? A Comparison of Natural Farming vs. Chemical Farming in Andhra Pradesh
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作者 Zakir Hussain Bhavana Boppana +2 位作者 Himabindu Anisetti Reshma Soma Sushmita Gangisetty 《Agricultural Sciences》 2022年第3期358-377,共20页
The global decline in farmland bird populations in India is often ignored. The overuse of agrochemicals in farming is the root cause of all these catastrophic results. There is ample evidence in the literature that tr... The global decline in farmland bird populations in India is often ignored. The overuse of agrochemicals in farming is the root cause of all these catastrophic results. There is ample evidence in the literature that transitioning to agroecological practices may reverse this trend. We anticipated that the bird population visiting natural farming-Andhra Pradesh Community managed Natural Farming (APCNF), a novel farming approach popular in India, will increase. The study used nested design to compare the number of bird visitations in natural farming versus chemical farming to determine whether natural farming can enhance the bird numbers and diversity. Furthermore, we analyzed the bird species visits to natural and chemical farms in different agroecological zones in Andhra Pradesh, the southernmost state of India. We used the point count survey approach to count the birds on comparable farms. MANOVA and non-parametric analysis are used to examine the findings. The bird species were ranked using a Likert scale. The results show that the average bird population visiting natural vs. chemical farms varies significantly at the 0.05 level of significance, and the bird species visiting both natural farming fields and chemical farms varies between geographies and time interval. 展开更多
关键词 Bird population Natural farming versus Chemical farming Andhra Pradesh India
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计及尾流的风电场智能等效建模及偏航优化控制
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作者 蔡玮 胡阳 刘吉臻 《动力工程学报》 CAS CSCD 北大核心 2024年第7期1051-1059,共9页
大型风电场中存在的尾流干扰会降低风电场整体输出功率,因此需要对风电场建立等效模型,并通过优化尾流分布来提升风电场整体功率输出能力。在所提出的新型风电场偏航优化框架中,提出了一种利用参数监督学习和正则化技术改进的径向基函... 大型风电场中存在的尾流干扰会降低风电场整体输出功率,因此需要对风电场建立等效模型,并通过优化尾流分布来提升风电场整体功率输出能力。在所提出的新型风电场偏航优化框架中,提出了一种利用参数监督学习和正则化技术改进的径向基函数神经网络算法,并建立了面向多自由度偏航控制的风电场功率转换智能等效模型。在该模型的基础上,定义了以风电机组偏航角为决策变量的场级最大输出功率优化问题,提出了一种改进的精英多种群遗传算法并进行优化求解,得到各机组偏航角优化值以减少机组间尾流干扰。利用实际风电场布局和风况数据进行了仿真测试。结果表明:所建立的风电场功率转换智能等效模型与其实际特性吻合良好,在特定风况下,偏航优化控制使得风电场总功率提升718.79 kW;连续风况下,所提优化控制方法在不同风况下均有明显的优化效果,风电场总功率平均提升1208 kW,验证了所提出的新型风电场偏航优化框架在提升风电场整体输出功率上的优越性。 展开更多
关键词 风电场 尾流效应 径向基函数 神经网络 偏航角优化 多种群遗传算法
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西部农牧交错带互助养老服务优化路径研究 被引量:1
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作者 刘亚萍 朝乐门 《财经理论研究》 2024年第1期39-50,共12页
受到地区经济发展不平衡以及劳动年龄人口外流等因素的影响,我国西部农村牧区养老问题严峻,老年人的养老环境及养老模式选择问题亟待各界关注。为解决养老问题,互助养老逐步在农村牧区兴起,并得到了广泛推广。本文通过对我国西部农牧交... 受到地区经济发展不平衡以及劳动年龄人口外流等因素的影响,我国西部农村牧区养老问题严峻,老年人的养老环境及养老模式选择问题亟待各界关注。为解决养老问题,互助养老逐步在农村牧区兴起,并得到了广泛推广。本文通过对我国西部农牧交错带老年人互助养老服务现状进行田野调查,运用扎根理论解析这一特殊区域互助养老模式运行过程中的瓶颈,归纳出3个主范畴、8个副范畴和相对应的23个子范畴。研究发现,虽然互助养老模式在不同地区的实践中成效显著,但在推进过程中面临着发展后劲不足的问题,主要存在互助服务空壳运行、基本养老资源匮乏与基层治理能力不足等三大问题范畴,范畴与范畴之间存在着内在的联系,不同维度又有各自的问题。研究认为,要从丰富互助养老服务内容、社会化运营互助养老幸福院、提升基层治理能力、涵养互助文化、养老政策向农村牧区倾斜、提升经济保障与增强服务提供等方面进行优化,从而实现西部农牧交错带互助养老服务的完善。 展开更多
关键词 人口老龄化 农牧交错带 互助养老 基层治理 扎根理论
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Characterising populations living close to intensive farming and composting facilities in England 被引量:2
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作者 Philippa Douglas Daniela Fecht Deborah Jarvis 《Frontiers of Environmental Science & Engineering》 SCIE EI CAS CSCD 2021年第3期97-109,共13页
Bioaerosol exposure has been linked to adverse respiratory conditions.Intensive farming and composting facilities are important anthropogenic sources of bioaerosols.We aimed to characterise populations living close to... Bioaerosol exposure has been linked to adverse respiratory conditions.Intensive farming and composting facilities are important anthropogenic sources of bioaerosols.We aimed to characterise populations living close to intensive farming and composting facilities.We also infer whether the public are becoming more concerned about anthropogenic bioaerosol emissions,using reports of air pollution related incidents attributed to facilities.We mapped the location of 1,257 intensive farming and 310 composting facilities in England in relation to the resident population and its characteristics(sex and age),area characteristics(deprivation proxy and rural/urban classification)and school locations stratified by pre-defined distance bands from these bioaerosol sources.We also calculated the average number of air pollution related incidents per year per facility.We found that more than 16%of the population and 15%of schools are located within 4,828 m of an intensive farming facility or 4,000 m of a composting facility;few people(0.01%)live very close to these sites and tend to be older people.Close to composting facilities,populations are more likely to be urban and more deprived.The number of incidents were attributed to a small proportion of facilities;population characteristics around these facilities were similar.Results indicate that populations living near composting facilities(particularly>250 to≤4,000 m)are mostly located in ur6an areas(80188%of the population),which supports the need for more community health studies to be conducted.Results could also be used to inform risk management strategies at facilities with higher numbers of incidents. 展开更多
关键词 COMPOSTING Intensive farming BIOAEROSOL population characteristics Public health
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软刺裸裂尻鱼耳石日轮及年轮沉积规律研究 被引量:1
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作者 严太明 蒲勇 +7 位作者 陈琪琪 高阔 郑利 焦圆圆 熊金鑫 赖柏霖 唐子婷 何智 《水生生物学报》 CAS CSCD 北大核心 2023年第9期1506-1513,共8页
研究利用软刺裸裂尻鱼(Schizopygopsis malacanthus)确证了耳石生长轮沉积规律,并在此基础上,探究了其生长轮与年轮关系,推算了第一年轮形成时间。研究结果表明:仔鱼微耳石第一轮纹在出膜后第二天形成,在实验条件下,轮纹沉积具有日周期... 研究利用软刺裸裂尻鱼(Schizopygopsis malacanthus)确证了耳石生长轮沉积规律,并在此基础上,探究了其生长轮与年轮关系,推算了第一年轮形成时间。研究结果表明:仔鱼微耳石第一轮纹在出膜后第二天形成,在实验条件下,轮纹沉积具有日周期性,生长轮为日轮;成鱼轮纹沉积具有年周期性,生长轮每年增加1轮。基于耳石日轮技术推算养殖和野生软刺裸裂尻鱼第一年轮形成时间分别为2021年1月28日至3月13日(n=40)和2017年3月8日至5月10日(n=75)。养殖和野生样本耳石轮纹数年际间的分析结果发现,软刺裸裂尻鱼耳石轮纹数和耳石年生长宽度随着年龄增加逐渐降低,耳石年生长面积随着年龄增加逐渐增加。这些结果揭示了软刺裸裂尻鱼耳石轮纹沉积规律,有助于增加年龄鉴定的准确性,进而为种群动态研究和渔业管理政策制定等提供参考。 展开更多
关键词 耳石 日轮 年轮 养殖群体 野生群体 软刺裸裂尻鱼
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北海道农业的发展历程与人口减少带来的挑战及其应对
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作者 黑﨑宏 张帅(译) 《日本研究》 2023年第2期82-96,共15页
20世纪60年代,日本农业主要由拥有小规模土地的家庭经营。为了实现农业结构现代化,日本政府计划通过转让农地所有权的方式扩大农业规模。然而农业用地价格的高涨使得日本整体农业规模扩大的目标未能实现,除北海道外,大部分地区依然停留... 20世纪60年代,日本农业主要由拥有小规模土地的家庭经营。为了实现农业结构现代化,日本政府计划通过转让农地所有权的方式扩大农业规模。然而农业用地价格的高涨使得日本整体农业规模扩大的目标未能实现,除北海道外,大部分地区依然停留在小规模兼业农户水平。在北海道,农业用地价格虽有增长,但其涨幅没有超过收益还原法估算的农业用地定价;土地改革等相关政策的实施,为农业机械的高效利用提供了支持;制造业发展滞后,农民难以在其他行业兼职。这些都为北海道的土地利用型农业规模的扩大起到了促进作用。今天,集落营农组织和股份公司等法人经营者一方面接收来自脱离农业家庭的土地,一方面增加租用农田,在农业领域发挥着越来越重要的作用,政府期望这样的经营者承担今后日本粮食的供应。北海道农业仍以家庭经营为主,法人经营者虽有所增加,但其一半以上本质上仍是家庭式经营,它们企业式的管理能力不断提高,以自有土地为主。家庭经营因其具有目标共有、便于协调和分配劳动等方面的优势,显示了家族经营固有的韧性。今天,北海道与日本其他地区同样,面临着农村人口减少、资源和能源成本迅速上升等问题,农业的可持续发展面临巨大挑战。因此,我们有必要通过普及智慧农业技术等方式进一步提高生产率,利用有机物循环防止土壤退化,推进生物质发电等措施以应对全球气候变暖等问题。 展开更多
关键词 家庭农业经营 集落营农组织 农业人口 土地改革 智慧农业
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2020-2021年山西省规模化牛场牛传染性鼻气管炎血清学调查
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作者 韩文儒 刘文俊 +6 位作者 杨丽华 董春光 韩一超 武守艳 付国兵 李永忠 邱建东 《中国奶牛》 2023年第8期26-30,共5页
为了解牛传染性鼻气管炎近期在山西省规模化牛场的流行情况,试验采用ELISA方法对牛血清中牛传染性鼻气管炎的抗体水平进行了研究。结果表明:山西省从北到南不同区域的规模化牛场群体阳性率达到92.31%,个体阳性率达到66.65%。其中2020年... 为了解牛传染性鼻气管炎近期在山西省规模化牛场的流行情况,试验采用ELISA方法对牛血清中牛传染性鼻气管炎的抗体水平进行了研究。结果表明:山西省从北到南不同区域的规模化牛场群体阳性率达到92.31%,个体阳性率达到66.65%。其中2020年晋北区域、晋中区域、晋南区域牛场的牛传染性鼻气管炎抗体个体阳性率均大于70%,晋南区域的阳性率最高,为89.67%;乳用牛高达90.84%,肉用牛为47.56%。2021年晋中区域、晋南区域牛场的牛传染性鼻气管炎抗体个体阳性率分别由2020年的71.95%、89.67%降为31.25%、52.35%;乳用牛为52.80%,肉用牛为27.27%。说明山西省从北到南各个区域的规模化牛场已普遍存在牛传染性鼻气管炎病毒感染,不同区域规模化养殖场的感染率不相同,乳用牛的感染率高于肉用牛。 展开更多
关键词 规模化牛场 牛传染性鼻气管炎 不同区域 抗体群体阳性率 抗体个体阳性率
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叉子圆柏古树全雄种群培养箱扦插 被引量:1
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作者 靳晓丽 黄茂林 《甘肃林业科技》 2023年第2期13-16,共4页
庆阳华池县白马林场残存叉子圆柏全雄古树群落,为了保护这一古老种质,探索其繁衍机制,野外采集枝条,开展光照培养箱扦插试验。结果表明,白马林场叉子圆柏可以扦插成活,珍珠岩、蛭石、细沙基质促进插穗生根成活的效应依次减弱,嫩枝插穗... 庆阳华池县白马林场残存叉子圆柏全雄古树群落,为了保护这一古老种质,探索其繁衍机制,野外采集枝条,开展光照培养箱扦插试验。结果表明,白马林场叉子圆柏可以扦插成活,珍珠岩、蛭石、细沙基质促进插穗生根成活的效应依次减弱,嫩枝插穗生根性能优于硬枝,ABT1号生根粉速蘸能促进生根。总之,白马林场叉子圆柏枝条具备生根性能,可以无性繁殖;改进扦插基质、生根剂等条件有望完善白马林场叉子圆柏扦插育苗技术。总之,白马林场的叉子圆柏是针叶树中的竹类。 展开更多
关键词 叉子圆柏 全雄种群 古树 扦插 白马林场
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基于mtDNA Cytb序列分析养殖与野生刀鲚群体的遗传多样性 被引量:18
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作者 魏广莲 徐钢春 +2 位作者 顾若波 李建林 徐跑 《江西农业大学学报》 CAS CSCD 北大核心 2012年第6期1216-1221,1244,共7页
为比较刀鲚(Coilia nasus)的人工养殖群体与野生群体的遗传结构差异,为刀鲚的种质资源保护和养殖业的可持续发展提供科学依据,应用线粒体DNA细胞色素b基因的序列分析法研究了灌江纳苗养殖刀鲚子三代(F3)、洄游刀鲚(长江野生群体)和湖鲚... 为比较刀鲚(Coilia nasus)的人工养殖群体与野生群体的遗传结构差异,为刀鲚的种质资源保护和养殖业的可持续发展提供科学依据,应用线粒体DNA细胞色素b基因的序列分析法研究了灌江纳苗养殖刀鲚子三代(F3)、洄游刀鲚(长江野生群体)和湖鲚3个淡水生活环境下的群体遗传多样性。结果显示:刀鲚线粒体DNA细胞色素b基因大小为1 141 bp;在3个群体22尾个体中,找到12种不同的单倍型,单倍型多态性(h)为0.922,多态位点(S)为18,其中单一多态位点9个,简约信息位点9个,核苷酸多样性(π)为0.004 1,平均核苷酸差异数(K)为4.714,平均遗传距离为0.004 2。洄游刀鲚和养殖刀鲚群体的核苷酸多样性、遗传距离都比湖鲚高,说明养殖刀鲚比湖鲚的遗传多样性要丰富,仍保持着较高的遗传多样性。 展开更多
关键词 刀鲚 养殖群体 野生群体 细胞色素B 遗传多样性
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我国麝养殖种群现状及其养殖业发展的分析 被引量:33
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作者 李林海 黄祥云 +5 位作者 刘刚 王文霞 卫宁 刘燕 胡德夫 梦梦 《四川动物》 CSCD 北大核心 2012年第3期492-496,共5页
我国麝养殖是解决麝类野生种群保护和中医药麝香来源的关键环节,是极为重要的野生动物养殖业。通过调查得出,截至2011年全国养殖麝已达8400余头,主要分布于四川、陕西等省份;养殖麝种群雄雌比率为1∶0.97,成幼比率为1∶0.53,表明养殖麝... 我国麝养殖是解决麝类野生种群保护和中医药麝香来源的关键环节,是极为重要的野生动物养殖业。通过调查得出,截至2011年全国养殖麝已达8400余头,主要分布于四川、陕西等省份;养殖麝种群雄雌比率为1∶0.97,成幼比率为1∶0.53,表明养殖麝种群处于快速增长状态,种群结构基本合理。结合目前麝养殖业资料的调查,分析了养殖规模、养殖技术、种源管理、产业政策对麝养殖产业发展的作用并提出提升麝养殖业发展的对策。 展开更多
关键词 养殖种群 养殖业 现状 分析
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秸秆覆盖下旱作水稻的生长发育特征研究 被引量:17
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作者 盛海君 周春霖 +2 位作者 沈其荣 徐阳春 封克 《中国水稻科学》 CAS CSCD 北大核心 2004年第1期53-58,共6页
通过半腐解秸秆覆盖旱作、地膜覆盖旱作、裸地旱作比较试验 ,研究了在田间覆盖条件下旱作水稻的生长发育以及产量形成特征。结果表明 ,在水稻生长期 ,降雨量为 4 4 0mm条件下 ,与其他旱作相比 ,采用半腐解秸秆覆盖 ,水稻生育前期植株个... 通过半腐解秸秆覆盖旱作、地膜覆盖旱作、裸地旱作比较试验 ,研究了在田间覆盖条件下旱作水稻的生长发育以及产量形成特征。结果表明 ,在水稻生长期 ,降雨量为 4 4 0mm条件下 ,与其他旱作相比 ,采用半腐解秸秆覆盖 ,水稻生育前期植株个体生长受到一定抑制 ,但生育中后期有利于水稻植株的生长发育 ,分蘖成穗率较高 ,冠层叶长 ,叶面积大 ,光合功能强 ,每穗结实粒数多 ,粒重大 ,产量高。 展开更多
关键词 半腐解秸秆 覆盖农作 水稻 旱作 群体特征 产量
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栽培措施对烟田前期烟蚜和烟蚜茧蜂种群数量的影响 被引量:25
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作者 侯茂林 王福莲 万方浩 《昆虫知识》 CSCD 北大核心 2004年第6期563-565,共3页
通过设置 5种类型烟田 ,研究了栽培措施对烟田前期烟蚜Myzuspersicae(Sulzer)和烟蚜茧蜂Aphidiusgifuehsis(Ashmead)种群数量的影响。地膜和耕作方式对烟田前期烟蚜种群数量均有显著影响。不同类型烟田烟蚜种群数量大小依次为桃园附近... 通过设置 5种类型烟田 ,研究了栽培措施对烟田前期烟蚜Myzuspersicae(Sulzer)和烟蚜茧蜂Aphidiusgifuehsis(Ashmead)种群数量的影响。地膜和耕作方式对烟田前期烟蚜种群数量均有显著影响。不同类型烟田烟蚜种群数量大小依次为桃园附近、纯作未覆膜、间作未覆膜、纯作覆膜、间作覆膜烟田。其中 ,桃园附近烟田烟蚜种群数量显著高于其它烟田 ,未覆膜烟田高于覆膜烟田 ,纯作烟田又高于间作烟田。地膜对烟田前期烟蚜茧蜂种群数量有显著影响。覆膜烟田烟蚜茧蜂种群数量高于未覆膜烟田。因此 ,烟田覆膜有利于降低烟蚜种群数量、增大烟蚜茧蜂种群数量 ;间作也能在一定程度上抑制烟蚜种群增长。 展开更多
关键词 烟田 烟蚜 覆膜 蚜茧蜂 蜂种 间作 种群数量 种群增长 桃园 大小
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长期稻鸭共作对稻田杂草群落组成及物种多样性的影响 被引量:61
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作者 魏守辉 强胜 +5 位作者 马波 韦继光 陈建卫 吴建强 谢桐洲 沈晓昆 《植物生态学报》 CAS CSCD 北大核心 2006年第1期9-16,共8页
2000~2003年连续4年研究了稻鸭共作条件下田间杂草群落的特征及其动态变化规律。结果表明,在长期稻鸭共作条件下,田间杂草密度逐年降低,下降趋势符合阻滞模型Y=k+a·e^bx,模型参数b反映了杂草种群的下降速率。在稻田6种主要... 2000~2003年连续4年研究了稻鸭共作条件下田间杂草群落的特征及其动态变化规律。结果表明,在长期稻鸭共作条件下,田间杂草密度逐年降低,下降趋势符合阻滞模型Y=k+a·e^bx,模型参数b反映了杂草种群的下降速率。在稻田6种主要杂草中,水虱草(Fimbristylis miliaceae)、陌上菜(Lindernia procumbens)、丁香蓼(Ludwigia prostrata)种群数量降低较快,鸭舌草(Monochoria vaginalis)、异型莎草(Cyperus difformis)次之,稗(Echinochloa crusgalli)最慢。稻鸭共作使稻田杂草群落的物种多样性持续降低,群落均匀度提高,群落相似性与稻鸭共作前相比逐年降低。说明稻鸭共作改变了田间杂草的群落结构,有利于限制杂草的发生危害。随着稻鸭共作的连年进行,对田间杂草的控制效果逐渐上升,4年后达99%以上。稻鸭共作是稻田替代化学除草的一种非常有效的生物、生态控草措施,具有显著的经济和生态效益。 展开更多
关键词 稻鸭共作 种群动态 物种多样性 群落均匀度 杂草综合管理
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稻-鸭农作系统对稻田生物种群的影响 被引量:14
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作者 禹盛苗 朱练峰 +2 位作者 欧阳由男 许德海 金千瑜 《应用生态学报》 CAS CSCD 北大核心 2008年第4期807-812,共6页
通过田间试验,研究了稻-鸭农作系统对稻田有关生物种群的影响.结果表明:稻鸭共育对稻田相关昆虫、杂草、病原菌等有害生物的发生和危害及天敌数量具有较大影响.与不养鸭相比,稻鸭共育后12 d和42 d,水稻基部害虫飞虱及叶蝉的数量平均减少... 通过田间试验,研究了稻-鸭农作系统对稻田有关生物种群的影响.结果表明:稻鸭共育对稻田相关昆虫、杂草、病原菌等有害生物的发生和危害及天敌数量具有较大影响.与不养鸭相比,稻鸭共育后12 d和42 d,水稻基部害虫飞虱及叶蝉的数量平均减少64.8%和78.5%;稻鸭共育后15 d和45 d,稻田杂草平均减少67.7%和98.1%;水稻分蘖高峰期和齐穗期的纹枯病病情指数分别降低了40.4%和62.0%.稻鸭共育还增加了稻田害虫天敌蜘蛛的数量,抑制了水稻害虫的危害. 展开更多
关键词 稻鸭农作系统 生物种群 病虫害 杂草 生物防治
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稻鸭共育模式下水稻根际土壤真菌和细菌种群多样性分析 被引量:26
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作者 廖咏梅 黄元腾吉 +4 位作者 韩宁宁 凌展 邹承武 史鼎鼎 蒋代华 《南方农业学报》 CAS CSCD 北大核心 2019年第1期59-67,共9页
【目的】比较稻鸭共育模式与常规管理模式种植水稻的根际土壤微生物种群多样性,为利用土壤微生物多样性开展水稻生态栽培提供科学依据。【方法】采集常规管理模式水稻根际土壤样品(记为S2)和稻鸭共育模式水稻根际土壤样品(记为S3),采用... 【目的】比较稻鸭共育模式与常规管理模式种植水稻的根际土壤微生物种群多样性,为利用土壤微生物多样性开展水稻生态栽培提供科学依据。【方法】采集常规管理模式水稻根际土壤样品(记为S2)和稻鸭共育模式水稻根际土壤样品(记为S3),采用电位法测定土壤pH、重铬酸钾—外加热法测定土壤有机质含量;针对土壤样品真菌ITS1~ITS2区域和细菌16S rDNA扩增子V3~V4区域进行Illumina MiSeq 2×300 bp双末端测序,分析两种模式土壤真菌和细菌的种类及丰度差异。【结果】S3的p H为5.10,有机质含量为23.91 g/kg;S2的pH为5.34,有机质含量为19.84 g/kg。在真菌门水平上,两种管理模式的根际土壤优势门均为子囊菌门(Ascomycota),S3中子囊菌门的相对丰度为42.36%,S2为93.67%,两者相差2.21倍;在真菌属的水平上,S3的优势属为毛壳菌属(Chaetomium),相对丰度为2.63%,而S2的毛壳菌属相对丰度仅为0.26%,两者相差10.12倍;S3中居第2位的属是嗜热真菌属(Mycothermus),相对丰度为2.21%,而S2的嗜热真菌属相对丰度为0.05%,两者相差44.20倍;S2的优势属是黑盘孢属(Melanconiella),相对丰度为6.66%,而S3的黑盘孢属相对丰度为0.26%,两者相差25.62倍。两种管理模式下相对丰度居前2位的细菌门均为变形菌门(Proteobacteria)和酸杆菌门(Acidobacteria),S3中变形菌门的相对丰度为40.90%,S2为29.45%,两者相差1.38倍;S3中酸杆菌门的相对丰度为18.90%,S2为27.84%,两者相差1.47倍;两种管理模式下相对丰度居前10的细菌属相同,其中7个属隶属变形菌门[其中3个属隶属于根瘤菌目(Rhizobiales)、3个属于隶属粘细菌目(Myxococcales)、1个属隶属于δ-变形菌纲未分目(unidentified Deltaproteobacteria)]、3个属隶属于酸杆菌门,10个属中仅有红微菌属(Rhodomicrobium)在两种管理模式土壤中相对丰度相差2.23倍(S3为1.18%,S2为0.53%),其他9个属相差均在1.00倍左右。【结论】与常规管理模式比较,稻鸭共育模式的水稻根际土壤pH略低,有机质稍高,真菌的种群结构丰富,而细菌的优势门和优势属无明显差异。 展开更多
关键词 稻鸭共育模式 水稻 根际土壤 真菌 细菌 种群多样性
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