连作年限对红壤旱地芝麻产量和主要病害的影响

为了探讨连作年限对红壤旱地芝麻产量和主要病害的发生规律的影响,采用定位试验,研究了正茬、连作1 a、2 a、3 a对芝麻相关性状的影响。结果表明,连作1 a、2 a、3 a与正茬比较芝麻产量分别降低14.0%、45.6%、64.4%,单株蒴果数分别减少25.4%、17.5%、55.9%,千粒重分别减少20.5%、8.5%、22.2%。连作1 a与连作3 a的每蒴粒数较正茬分别减少2.0%和14.5%。红壤旱地上芝麻连作会使茎点枯病和青枯病的病情指数呈现上升趋势,其中茎点枯病从正茬的6.80%增加到连作3 a的51.63%,而青枯病从正茬的2.54%增加到连作3 a的44.75%。这说明芝麻连作对产量、产量构成因素、主要病害病情指数的影响大,为了提高芝麻产量应实行轮作换茬。     

连作年限对红壤旱地芝麻产量和主要病害的影响

为了探讨连作年限对红壤旱地芝麻产量和主要病害的发生规律的影响,采用定位试验,研究了正茬、连作1 a、2 a、3 a对芝麻相关性状的影响。结果表明,连作1 a、2 a、3 a与正茬比较芝麻产量分别降低14.0%、45.6%、64.4%,单株蒴果数分别减少25.4%、17.5%、55.9%,千粒重分别减少20.5%、8.5%、22.2%。连作1 a与连作3 a的每蒴粒数较正茬分别减少2.0%和14.5%。红壤旱地上芝麻连作会使茎点枯病和青枯病的病情指数呈现上升趋势,其中茎点枯病从正茬的6.80%增加到连作3 a的51.63%,而青枯病从正茬的2.54%增加到连作3 a的44.75%。这说明芝麻连作对产量、产量构成因素、主要病害病情指数的影响大,为了提高芝麻产量应实行轮作换茬。     

美国蓝鳃太阳鱼养殖技术

报道了蓝鳃太阳鱼(Lipomis macroehius)的外部形态、生活、生长、繁殖习性、食性等生物学特征，以及鱼苗培育、成鱼养殖、鱼病防治技术。分析了该鱼发展中存在的问题，并提出建议。     

高锰酸钾防治对虾幼体聚缩虫病的研究

在对虾育苗期间,以选择施用0.5ppm和1ppm高锰酸钾、换水补药的方式为预防措施,以泼洒2～4ppm高锰酸钾短期药浴为应急治疗方法,连续2年在对虾育苗生产中取得了抑制和杀灭聚缩虫病成功率为100％,每立方水体生产15～25万尾仔虾的良好效果。育苗水体长期施用0.5～1ppm高锰酸钾对对虾幼体、单胞藻、卤虫无毒害作用,对微粒饵料、水质因子亦无不良影响。高锰酸钾施用方便,成本低廉,投入成本只占万尾虾苗售价的万分之一左右,便于在大生产中推广应用。     

中华鳖“红底板病”病原菌的研究及防治

本文阐述了中华鳖红底板病的流行病学,病原菌的分离、培养、生化鉴定和菌体DNAGC mol％的测定以及毒性试验等,确定了致病菌为气单胞菌属;通过药敏试验及生产实践,提出了有效的防治措施。     

Influence of high dietary α-tocopherol intakes on specific immune response, nonspecific resistance factors and disease resistance of healthy and aflatoxin B1-induced immunocompromised Indian major carp, Labeo rohita (Hamilton)

The effect of aflatoxin treatment and/or feeding of a high level of α‐tocopherol on immune response and disease resistance was investigated in Indian major carp, Labeo rohita. Group A served as a healthy control, group B was treated with aflatoxin, group C was fed a high level of α‐tocopherol whereas group D was exposed both to aflatoxin and a high level of dietary α‐tocopherol for 60 days. Aflatoxin B₁ (AFB₁) was injected once intraperitoneally into fish on the first day of the experiment (groups B & D). High levels of DL‐α‐tocopherol (1000 mg kg^–1 feed) were provided to healthy as well as AFB₁‐treated immunocompromised fish for 60 days (groups C & D). At the end of the experiment blood samples were assayed for changes in nonspecific immunity and humoral protein levels. Disease resistance against two common bacterial pathogens viz., Aeromonas hydrophila and Edwardsiella tarda were evaluated in all groups. Significant (P < 0.05) suppression of specific immunity as measured through haemagglutination (HA) titre against sheep red blood cells (SRBCs) as well as bacterial (formalin‐killed E. tarda) agglutination titre; nonspecific resistance factors viz., globulin level, serum bactericidal and lysozyme activities, neutrophil activities, and disease resistance against two bacterial pathogens only in aflatoxin‐treated fish with respect to the control group, clearly indicated the immunosuppressive nature of aflatoxin. Feeding of a high level of α‐tocopherol to AFB₁‐treated immunocompromised fish significantly (P < 0.05) raised specific immunity, nonspecific resistance factors and disease resistance capacity when compared with aflatoxin‐exposed fish. Disease resistance and enhancement of immune status through feeding of high levels of α‐tocopherol to healthy as well as AFB₁‐treated immunocompromised fish confirmed the potential of α‐tocopherol in carp feed for prevention of disease and for combating natural/environmental immunosuppressants.     

Study on the distribution and expression of a DNA vaccine against lymphocystis disease virus in Japanese flounder (Paralichthys olivaceus)

The distribution and expression of lymphocystis disease virus (LCDV) vaccine, on the basis of DNA vaccine (pEGFP-N2-LCDV0.6 kb) construction, were analyzed in tissues of the Japanese flounder by PCR, RT-PCR and fluorescent microscopy. Results from PCR studies indicated that the vaccine-containing plasmids were distributed in injected muscle, muscle located opposite the injection site, hind intestine, gill, spleen, head kidney, liver and gonad 7 days after vaccination. However, these vaccine-containing plasmids disappeared by 90 days following vaccination. Fluorescent microscopy observations revealed that green fluorescence appeared in muscle, muscle located at the opposite side of the injection site, hind intestine, gill, spleen, head kidney and liver of fish 36 h after vaccination, and that green fluorescence did not appear in control tissue. The green fluorescence became weaker at 60 days post-vaccination, however, it remained detectable in the spleen 90 days post-vaccination. Results from RT-PCR studies indicated that the Mcp gene is expressed in all tissues of vaccinated fish 7-20 days after vaccination. These results demonstrate that the DNA vaccine is distributed and expressed in different tissues of vaccinated fish, and therefore, may have provided an antigen producing specific immune response.     

试验性抗菌药对仔猪水肿病治疗效果

保定市某猪场暴发疫病,经病理剖检、病原分离、生化试验、毒力试验等诊断方法获知此次疫情为致病性埃希氏大肠杆菌引起的猪水肿病。药敏实验表明,细菌分离物对青霉素、链霉素等常用抗生素有耐药性,对氟苯尼考、卡那霉素、环丙沙星等药物极敏。感染猪选用氟苯尼考治疗后康复。     

Reduced total hardness of fresh water enhances the efficacy of bathing as a treatment for amoebic gill disease in Atlantic salmon, Salmo salar L

The current treatment for amoebic gill disease (AGD)-affected Atlantic salmon involves bathing sea-caged fish in fresh water, often sourced from local dams, for 3-4 h. In both a small-scale laboratory and an on-farm field experiment, the effects of water hardness on the efficacy of freshwater bathing were assessed. Results showed that soft fresh water (19.3-37.4 mg L(-1) CaCO3), whether it be naturally soft city mains water or artificially softened dam water, was more efficacious at alleviating AGD in affected fish than hard fresh water (173-236.3 mg L(-1) CaCO3). Soft freshwater bathing significantly reduced viable gill amoebae numbers (from 73.9 to 40.9% of total count) and significantly alleviated gill pathology, both gross and histological. Following bathing, gross gill pathological scores of soft freshwater bathed fish lagged 2 weeks behind hard freshwater bathed fish. Significant gill lesion fragmentation, and shedding of lesion-associated hyperplastic tissue, was accompanied by a significant reduction in AGD-affected gill filaments in soft freshwater bathed fish. Furthermore, soft freshwater bathing alleviated the blood plasma electrolyte imbalance seen in control (sea water) and hard freshwater bathed fish. This study showed that the use of soft fresh water for bathing AGD-affected Atlantic salmon could be an improvement to the current method of treatment. Not only does it reduce gill amoeba numbers, but also, it is of a therapeutic advantage with the potential to reduce bathing frequency.