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121.
养分管理对安溪茶园土壤肥力及茶叶品质的影响 总被引:6,自引:0,他引:6
安溪是铁观音的主产区,茶园养分管理滞后已成为该地区茶叶生产的瓶颈,本研究旨在为该地区茶园的养分管理提供科学依据。试验于2015年在安溪县采集了50个茶园的茶青与土壤样品,测定了土壤5项主要肥力指标和茶青中9种主要次生代谢物含量;并根据茶农氮肥用量调研数据,初步将茶园养分管理划分为:少量、中量和过度型等三种方式。限制性主坐标轴分析发现,此分类方式可解释34.4%(P0.001)茶园土壤肥力参数的总体差异,说明此分类方式能反映出不同茶园养分管理的总体水平;并且,养分管理对表层土壤有效磷的影响最为显著。进一步分析表明,养分管理对茶青综合品质的影响可解释品质总差异的7.48%(P0.001);大部分茶青次生代谢物在中量型管理下含量最高。说明养分管理影响安溪茶园土壤的肥力状况,施肥量过高或过低均不利于高品质茶叶的生产,该地区的建议施氮量约为200~400 kg·hm~(–2)·a~(–1)。 相似文献
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124.
浅谈中职农业学校猪病防治教学改革 总被引:1,自引:0,他引:1
在新形势下,为了使学生掌握扎实的猪病防治理论知识和熟练的操作技能,适应社会需要,本文对目前一些中职农业学校猪病防治课程教学现状及存在问题做了一些分析,并提出了一些改革设想。 相似文献
125.
Yersinia ruckeri is the causative agent of enteric redmouth disease (ERM), a common pathogen affecting aquaculture facilities and implicated in large losses of cultured fish. Fisheries scientists continue to gain a greater understanding of the disease and the pathogen by investigating methods of identification and pre- and post-infection treatment. In this study, a real-time PCR probe set for Y. ruckeri was developed to detect daily changes in the bacterial load during pathogen challenges. Two species of fish, Chinook salmon, Oncorhynchus tshawytscha, and steelhead trout, Oncorhynchus mykiss, were exposed to two strains of Y. ruckeri (Hag and SC) during bath challenges. A subset of fish was killed daily for 14 days, and the kidney tissue was biopsied to enumerate copies of pathogen DNA per gram of tissue. While Chinook exposed to either the Hag or SC strains exhibited similar pathogen loads, those exposed to the Hag strain displayed higher mortality (~66%) than fish exposed to the SC strain (~24% mortality). Steelhead exposed to the Hag strain exhibited a greater pathogen load and higher mortality (~42%) than those exposed to the SC strain (<1% mortality). Steelhead challenged with either strain showed lower pathogen loads than Chinook. The study illustrates the efficacy of the probe set to enumerate Y. ruckeri bacterial growth in the kidneys of fish. Also, strains of Y. ruckeri display species-specific growth patterns that result in differential mortality and pathogen load. 相似文献
126.
日本对虾抗白斑病子三代的抗白斑综合征病毒感染能力及免疫特性 总被引:1,自引:1,他引:1
为了更好地进行日本对虾抗病良种的选育,本文用浓度为每毫升1×105个病毒粒子的对虾白斑综合征病毒(white spot syndrome virus,WSSV)粗提液注射感染抗白斑病日本对虾子三代和普通日本对虾,观察其死亡率,同时测定WSSV感染后0,4,24,48和96 h血淋巴酚氧化酶(PO)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)活力和蛋白含量.结果显示:注射WSSV 14 d内抗病子三代和普通对虾的平均死亡率分别为15%和85%,前者的抗病保护率达82.4%;感染前前者的各项免疫指标均高于后者,且PO,AKP和蛋白含量存在极显著差异(P<0.01);感染后两者血淋巴检测的5项指标在96 h内的变化趋势基本相似,除ACP以外,抗病子三代的其他指标都比普通日本对虾的高.研究结果表明,所选育的抗白斑病日本对虾子三代能够有效地抵抗对虾白斑综合征病毒的侵染,其免疫指标也高于普通日本对虾. 相似文献
127.
In this study, the possible influence of temperature on infectious pancreatic necrosis virus (IPNV)-induced apoptosis in a zebrafish liver epithelium (ZLE) cell line was investigated. At a lower temperature (18 degrees C), there was expression of viral proteins VP2 and VP3 at 4 h post-infection (p.i.). At this time no expression was found in the high temperature group at 28 degrees C. The cell survival ratio was 52 and 18% at 24 and 48 h p.i., respectively, during IPNV infection at 18 degrees C. In addition, we assayed for apoptosis in IPNV-infected cells with terminal deoxynucleotidyl transferase (TdT)-mediated end labelling (TUNEL) of DNA at different dosages of virus. We found a ratio of apoptotic cells of 8 and 25% at 12 and 18 h p.i., respectively, in the multiplicity of infection (MOI) 1 group. The MOI 10 group had 20 and 45% apoptotic cells at 12 and 18 h, respectively. Furthermore, at 18 degrees C IPNV activated the caspase-8 and 3 from 1.5 to 2 times at 12 and 18 h p.i., respectively. Taken together, these findings suggest that successful virus replication occurs at the low temperature (18 degrees C) compared with the non-permissive temperature of 28 degrees C. Thus, IPNV replication is capable of activating caspase-8 and -3 and inducing host apoptosis. 相似文献
128.
从患病香鱼的体腔液中分离获得嗜水气单胞菌病原,经培养稀释的菌液,腹腔注射人工感染健康香鱼,出现典型的出血症后,进行血液生理生化指标的测定。结果发现,病鱼红细胞数量为(1.21±0.08)×1012个/L,血栓细胞数量(189.00±5.19)×1012个/L,较健康香鱼红细胞[(2.41±0.16)×1012个/L]、血栓细胞[(380.0±20.00)×1012个/L]呈极显著降低(P0.01),血红蛋白含量呈显著减少(P0.05),而白细胞数量却显著增加(P0.05)。染病香鱼总蛋白为(47.56±2.63)g/L,健康鱼为(49.23±3.06)g/L,经检验无显著差异;而碱性磷酸酶、Cl-、Ca2+等3项血液生化指标值均呈极显著减少(P0.01),乳酸脱氢酶呈极显著增加(P0.01)。 相似文献
129.
Atlantic salmon, S almo salar L., were exposed to different concentrations of Paramoeba sp. The lowest concentration which induced amoebic gill disease (AGD) was 230 Paramoeba sp. L–1 and the severity of infection increased with increasing concentration. The concentration of Paramoeba sp. positively correlated with the number of gill lesions ( R 2 > 0.7). This study provides evidence that Paramoeba sp. is the causative agent of AGD and describes an experimental model that enables the severity of the induced disease to be controlled. 相似文献
130.
Although a Yersinia pseudotuberculosis (Yptb) lung infection model has been developed to study Y. pestis pathogenesis, it is still necessary to establish a new animal model to mimic the pathophysiological features induced by Y. pestis infection. Here, we provide a new lung infection model using the Yptb strain, IP2777, which displayed rapid spread of bacteria to the liver, spleen, and blood. In addition, we examined whether TLR4 is involved in Yptb-induced pathogenesis in the lung infection model of mice we generated. Following lung infection of WT and TLR4-deficient mice with the Yptb strain IP2777, the survival rate, bacterial colonization, histopathology, and level of cytokines and chemokines in the lung, spleen, liver, and blood were analyzed. TLR4-deficient mice had a lower survival rate than WT mice in response to Yptb lung infection. Although the bacterial colonization and pathology of the lung were comparable between WT and TLR4-deficient mice, those of the spleen and liver were more severe in TLR4-deficient mice. In addition, the levels of TNF-α and CXCL2 in the liver and IL-6 and CXCL2 in the blood were higher in TLR4-deficient mice than in WT mice. Our results demonstrate that TLR4 is necessary for optimal host protection against Yptb lung infection and TLR4-deficient mice may serve as a better genetic model of Yptb infection for mimicking Y. pestis infection. 相似文献