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排序方式: 共有214条查询结果,搜索用时 31 毫秒
1.
Simple diagnosis by ethanol immersion (SDEI) to detect Glomerella cingulata was used to detect three other fungi that also cause latent infection of strawberry plants. Signs on strawberry leaves with asymptomatic latent infection by Colletotrichum acutatum became visible using SDEI. Salmon-pink conidial masses were produced in the acervuli on the treated leaves 5 days after incubation at 28°C. In the case of Dendrophoma obscurans, pycnidia with amber conidial masses formed 5 days after incubation at 28°C. The pycnidia were observed mainly on the ribs, and conidial masses exuded from the ostiole. These macroscopic conidial masses were similar to those of G. cingulata and C. acutatum. When water was dripped onto a lesion caused by D. obscurans, the pycnidia exuded white filamentous conidial masses, making the distinction of D. obscurans from G. cingulata or C. acutatum. On petioles with latent infection by Fusarium oxysporum f. sp. fragariae, white aerial hyphae grew out from the vascular tissues on the cut surface 3 days after incubation at 28°C and were easily observed by eye or with a loupe. Thus, SDEI was also useful for diagnosing latent infection of strawberry plants by C. acutatum, D. obscurans, and F. oxysporum f. sp. fragariae.  相似文献   
2.
15种杀虫剂对草地贪夜蛾卵的毒力测定   总被引:2,自引:0,他引:2  
采用浸卵法测定了15种杀虫剂对草地贪夜蛾卵的毒力,并比较了不同杀虫剂的毒力水平。结果表明:100 mg/L处理后48 h,甲氨基阿维菌素苯甲酸盐(甲维盐)和灭多威对草地贪夜蛾卵孵化抑制率最高,达到100%,其LC 50分别为12.67 mg/L和16.95 mg/L;而200 mg/L的氯虫苯甲酰胺、多杀霉素、阿维菌素、高效氯氰菊酯、虱螨脲、辛硫磷和杀螟丹分别处理后72 h对草地贪夜蛾卵的孵化抑制率次之,在69.6%~87.65%之间,其LC 50分别为44.1、50.9、78.37、79.0、98.15、126.8 mg/L和137.7 mg/L。依据毒力测定的结果和高效低毒类杀虫剂优先选用的原则,推荐选择甲维盐、氯虫苯甲酰胺、多杀霉素、阿维菌素和高效氯氰菊酯作为防治草地贪夜蛾卵的主要药剂。  相似文献   
3.
Various tissues of menhaden fish were analyzed for macro and micro minerals. Tissues selected were gill, heart, intestine, kidney, liver, muscle, spleen, and stomach. Phosphorus, calcium, magnesium, sodium, manganese, and zinc were found to be most concentrated in the gill. Potassium, iron, and boron were least concentrated in the gill. Liver contained the highest concentration of copper, selenium and boron. The stomach was the highest in potassium and lowest in phosphorus. Sodium and selenium concentrations were lowest in the muscle. Mercury concentrations were approximately 2 mg/g dry matter in all tissues  相似文献   
4.
以果蔗(Badila)茎尖脱毒组培苗为材料,利用间歇浸没式生物反应器(Temporary immersion bioreactors TIBs)进行组培快繁的技术体系的研究。结果表明:(1)使用TIBs系统进行甘蔗组织培养一代增殖较传统方法高出10倍以上;(2)TIBs系统以第4代继代材料为宜;(3)接种密度在10~15株/L培养基最有利于甘蔗组培苗的增殖和生长;(4)TIBs系统中6-BA浓度为0.5~1.0mg/L时适合于增殖培养,NAA浓度为4mg/L时有利于根的诱导;(5)浸没间歇频率在1min/3h时增殖和生长表现较为优异,1min/6h时有利于根的诱导和根的生长。  相似文献   
5.
OBJECTIVE: To quantify stripping in traditional dipping operations and to revise dipping methods, based on prediction of stripping so that a more stable concentration of pesticide in the dipwash is achieved. DESIGN AND METHODS: Plunge and shower dips were operated sequentially according to traditional and revised dipping instructions. Dips were operated by continuous and intermittent replenishment. Samples of mixed dipwash were collected periodically and assayed for pesticide (diazinon) concentration. RESULTS: Diagrammatic representations of pesticide concentration versus number of sheep dipped indicated traditional dipping leads to wide variations in the concentration of pesticide in dipwash during dipping. Intermittent replenishment led to a 'saw-tooth' pattern in the pesticide concentration. Traditional continuous replenishment (using the starting concentration of pesticide) indicated both the rate and extent of stripping was higher in shower dipping. If sufficient sheep were dipped, equilibrium was reached between the rate of pesticide replenishment and removal. An alternative method of dip operation by continuous replenishment, using a low starting concentration of pesticide and a replenishment concentration high enough to offset the pesticide loss through stripping resulted in a more stable concentration of pesticide in the dip. CONCLUSION: Revision of dipping instructions can lead to exposure of sheep to stable concentrations of stripping pesticide during dipping.  相似文献   
6.
Streptococcus iniae and Gyrodactylus niloticus are two common pathogens of cultured Nile tilapia, Oreochromis niloticus. We studied concurrent infection of tilapia by G. niloticus and S. iniae and evaluated whether parasitism in tilapia with Gyrodactylus increased susceptibility and mortality following immersion infection with S. iniae. Results showed that death mainly occurred in fish with G. niloticus and challenged with S. iniae (G-S group). The accumulative mortality (42.2%) was significantly higher in the G-S group than in fish not infected by the parasite (6.7%), but exposed to S. iniae. Bacteriological examination revealed S. iniae from > or =92% of dead or moribund fish challenged with S. iniae. Gyrodactylus not only damaged fish epithelium and provided entry for invasive bacteria but also was found to harbour viable cells of S. iniae for 24 and 72 h. Streptococcus iniae was isolated from 60% and 40% of G. niloticus collected from fish infected by intraperitoneal injection or immersion, respectively, at 24 h post-challenge. The present study confirms that parasitism of tilapia by G. niloticus increased host mortality following exposure to the bacterial pathogen S. iniae.  相似文献   
7.
甜瓜枯萎病接种方法比较试验初报   总被引:5,自引:1,他引:4  
分别采用灌根法、米饭粒接种法、蘸根法及胚根接种法对甜瓜枯萎病进行接种试验,拟为甜瓜抗病育种提供依据。结果表明:米饭粒接种法发病率最高,达到99%;胚根接种法最低,为10%;灌根法发病率为66.7%;蘸根法发病率为91%,且操作简单、精确,最适合进行甜瓜枯萎病抗病鉴定研究。  相似文献   
8.
应用间接ELISA方法,研究经嗜水气单胞菌(Aeromonas hydrophila)疫苗浸泡免疫后鳜(Siniperca chuatsi)皮肤黏液中抗体消长规律,以揭示鳜局部黏膜免疫在免疫保护中的作用及浸泡免疫的保护效果。结果表明,鳜皮肤黏液中抗体滴度在免疫后第7天达到峰值211,抗体从开始形成到消失持续21 d;添加佐剂(IMS1312、葡聚糖、莨菪碱、食盐)可以提高鳜皮肤黏液及血清中抗体滴度和相对免疫保护率,其中添加IMS1312组免疫保护率最高,达77.8%,免疫保护与抗体滴度成正相关(R2=0.79,P<0.05);以溶菌酶为代表的非特异性免疫在免疫后1周内即抗体未形成时,对鱼体起主要保护作用。此外,通过比较鳜血清与皮肤黏液中的抗体消长规律,发现血清中抗体滴度峰值出现时间较迟(第14天),抗体持续时间较长(42 d),初步推断鳜皮肤黏膜中可能存在相对独立于全身免疫系统的局部黏膜免疫系统。  相似文献   
9.
In this study, Intraperitoneal (IP) and bath immersion (BI) vaccine trials were conducted in fish with a mean weight of 6.3 g. Rainbow trout vaccinated with lipopolysaccharide (LPS) was 50 mg/L protein concentration and challenged by IP injection with 9.8 × 106 cell/ml of Yersinia ruckeri at 45 days post-immunization had a relative percent survival (RPS). To obtain an effective bath immersion vaccine against yersiniosis, LPS preparation was obtained from the Y. ruckeri and with the LPS antigen. After 28 and 60 days vaccinated fish with first and second immunizations by LPS were challenged via intraperitoneal injection with 9.8 × 106 cell/ml of Y. ruckeri for evaluating the mortality rates and calculating the relative percentage of survival (RPS). RPS value of experimental groups, which was significantly (P < 0.05) larger than that of the control group.  相似文献   
10.
棉花粉蚧(Phenacoccus solenopsis Tinsely)是一种近年来在世界范围内发生危害的入侵性害虫,已给巴基斯坦、印度等多国的棉花生产造成严重损失。2008 年中国大陆发现其发生,目前已在局部地区入侵棉田、造成危害,对中国棉花产业潜在威胁巨大。为了寻找合适的防治药剂,采用浸叶法测定了14 种杀虫剂对棉花粉蚧三龄若虫的毒力。结果表明,高效氯氟氰菊酯、丙溴磷、毒死蜱和阿维菌素相对毒力较高;随着处理时间延长,阿维菌素、甲维盐、多杀霉素和溴虫腈4 种杀虫剂对棉花粉蚧三龄若虫毒力上升明显。药后24 h,14 种药剂的相对毒力由高到低依次为高效氯氟氰菊酯、丙溴磷、毒死蜱、阿维菌素、辛硫磷、丁硫克百威、多杀霉素、溴虫腈、高效氯氰菊酯、灭多威、甲维盐、三唑磷、矿物油、鱼藤酮;药后48 h,14 种药剂的相对毒力由高到低依次为高效氯氟氰菊酯、丙溴磷、阿维菌素、毒死蜱、甲维盐、溴虫腈、多杀霉素、丁硫克百威、辛硫磷、高效氯氰菊酯、灭多威、三唑磷、矿物油、鱼藤酮,与药后24 h的相对毒力顺序略有变化。  相似文献   
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