Factors affecting the development of disease symptoms in potatoes infected by <Emphasis Type="Italic">Tobacco rattle virus</Emphasis>     

D.J. Robinson  M.F.B. Dale  D. Todd 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(9):921-928

Infection of potato plants with Tobacco rattle virus by its nematode vector can have different outcomes, including the development of spraing symptoms in progeny tubers. A novel syndrome described here comprises a generalized mottle in leaves on all stems, together with virtually total failure to produce daughter tubers. The outcome of infection depends partly on the potato genotype, but field trials with 15 varieties showed that the incidence and severity of spraing symptoms at three sites differed. There was no evidence that this was due to differences in virulence among the virus isolates at the sites, but it was probably the result of environmental differences that influenced the numbers and activity of the vector nematodes. At the most severely affected site, spraing symptoms were found in all varieties tested, except Record, including several that were not affected at the other two sites. Taking both severity and incidence of symptoms into account, the ranking of varieties was similar at each site. The incidence of spraing symptoms was greater in larger than in smaller tubers, and increased with later harvest dates, but did not increase when early harvested tubers were stored. Tobacco rattle viruswas detected in the roots of many of the weeds growing at one of the sites and in the roots of a few plants of the subsequent barley crop.  相似文献   

猪伪狂犬病基因缺失疫苗的制备、安全性、免疫原性、保存期测定及区域试验   总被引：3，自引：1，他引：3  

何启盖  方六荣  吴斌  刘正飞  吴美洲  肖少波  金梅林  陈焕春 《畜牧兽医学报》2005,36(10):1055-1063

为了提供有效的伪狂犬病疫苗，用鸡胚成纤维细胞扩大培养了PrV HB-98突变株（TK^-/gG^-/LacZ^＋），研制了伪狂犬病基因缺失疫苗，并对该疫苗经肌肉接种、经口等免疫途径的最小免疫剂量进行了测定，同时也对4批疫苗的安全性、效力、免疫期和保存期进行了检测；同时将4批疫苗用于免疫23个猪场的母猪、新生仔猪和育肥猪进行区域试验。测定结果表明，疫苗经上述两种途径接种对不同阶段猪的最小免疫剂量均为10^5.0 TCID50；10倍免疫剂量的疫苗对初生仔猪、15日龄仔猪和妊娠母猪是安全的，免疫猪能抵抗强毒的攻击；疫苗在4℃和-20℃下分别可保存6个月和12个月。对伪狂犬病毒抗体阴性的70日龄商品猪和种猪的免疫期为6个月。田间试验表明，4批猪伪狂犬病基因缺失疫苗安全有效，并可用于仔猪发病时的紧急接种。为猪伪狂犬病基因工程疫苗的制备与应用提供了有力的依据。  相似文献   

刺槐无性系种子园老龄母树截干矮化试验   总被引：2，自引：1，他引：1  

文彦忠 《防护林科技》2017,(5)

利用刺槐萌蘖力强的特性,对刺槐无性系种子园老龄化后的树体进行截干试验,促使其萌蘖形成新的树冠,并进行整形修剪,结果表明:老龄母树截干矮化,效果良好,达到预期目标。解决了原母树树体高大釆种困难的问题,为提高刺槐种子园老龄化后种子产量和质量进行了有益的探索。  相似文献   

Nanostructured liquid crystalline particle assisted delivery of 2,4-dichlorophenoxyacetic acid to weeds,crops and model plants     

《Crop Protection》2016

Routine agricultural practices are heavily dependent on the use of surfactants, many of which are toxic to humans and detrimental to the environment. In proof of concept work we have previously shown the potential of nanostructured liquid crystalline particles (NLCP) to safely interact with plant leaf cuticular surfaces with minimal impact on epicuticular waxes. Here we demonstrate the use of NLCP to effectively deliver the auxin herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) to plant leaves in laboratory and field studies. In the laboratory, the physiological stress responses of lupin, Lupinus angustifolius (L.) (Fabaceae) towards NLCP spray applications were shown to be much reduced in comparison with application of two common surfactants. Phytotoxicity assays of 2,4-D loaded NLCP were used to validate the herbicidal effects on Arabidopsis thaliana (L.) Heynth. (Brassicaceae) and established a similarity with that of surfactant assisted 2,4-D delivery when tested at a concentration of 0.1%. Field trials were conducted to test the efficacy of NLCP-assisted delivery of 2,4-D in comparison with commercial surfactants for the control of the invasive weed wild radish, Raphanus raphanistrum (L.) (Brassicaceae), in wheat, Triticum aestivum (L.) (Poaceae) crop fields. Compared against Estercide 800, a commercially available 2,4-D formulation, NLCP assisted delivery of 2,4-D was effective at low concentrations of 0.03% and 0.06%. The crop yield remained similar for all the tested concentrations and formulations of 2,4-D loaded NLCP and Estercide 800. This is the first report to directly show that, as an alternative to conventional methods, NLCP can be used under both laboratory and field conditions to successfully delivery an agrochemical.  相似文献   

The optimal nutrition of maize in the hungarian national long‐term field experimental network     

Tamás Kismányoky  Katalin Debreczeni 《Archives of Agronomy and Soil Science》2013,59(3-4):251-264

In Hungary, maize is grown on 1 million ha and occupies more than 20% of the arable land. The rich assortment of maize cultivars of different vegetation periods and different responses to nutritional effects, water supply etc. gives the growers the possibility to choose the cultivars suiting best the site characteristics (Jolânkai et al. 1999). Among the cereals maize has the highest genetical potential. To utilize its yield and quality potential, soil types of high nutrient content and regular nutrient supply are required (Gyõrffy, 1979). Both over‐ and under‐fertilization have an unfavourable effect on the yield and quality of maize (Debreczeni, 1985). Crops can be supplied with the appropriate nutrient amounts only with the knowledge of soil characteristics in the different agro‐ecological regions (nutrient content, water supply, soil compactness, pH, nutrient supplying capacity etc.). In Hungary, a network of long‐term field fertilization trials with uniform fertilizer treatments has been maintained at nine experimental sites representing different agro‐ecological regions of the country. This experimental network gives a basis to test the nutrient responses of our main crops and calibrate their optimal nutrient supply (Kismányoky, 1991).  相似文献   

两种底拖网渔业资源调查船捕捞效率标准化分析     

刘尊雷  杨林林  袁兴伟  严利平  张辉  程家骅 《中国水产科学》2020,27(7):834-845

渔业资源科学调查是开展渔业资源状况评价、物种保护和管理等分析的重要数据来源，当调查方式发生变化时，维持数据的时间一致性至关重要。因此，原位试验获取不同调查方式的捕捞效率校正因子（fishing power correction，FPC）成为资源状况评价的先决条件。本研究通过平行拖网对比试验分析了科学调查船“中渔科211”（试验船）和生产性渔船“浙嵊渔10201-10243”（标准船）在开展渔业资源调查时对不同种类或类群的渔获率差异。结果表明，标准船和试验船平均渔获率分别为（47.27~1836.72）kg/nmile²和（12.28~311.85）kg/nmile²。标准船主要种类为小黄鱼（），渔获率范围分别为（1.17~1113.26）kg/nmile²和（0~565.39）kg/nmile²；试验船主要种类为鳀（），渔获率范围分别为（0~277.59）kg/nmile²和（0~125.24）kg/nmile²。2种调查方式对不同种类/组的渔获率随深度变化趋势出现分化，其中总渔获率、鱼类、银鲳（Apogonichthys lineatus）、绿鳍鱼（）8个种类/组表现为相似的变化趋势；甲壳类、细点圆趾蟹（Erisphex pottii）5个种类/组变化趋势相反；头足类、小黄鱼、龙头鱼在各深度变化具有异质性特征。这种变化与网口垂直扩张和所在水层位置有关。均值比和Kappenman方法估计的总渔获率FPC分别为0.35（95%置信区间为0.24~0.61）和0.43（95%置信区间为0.27~0.70），各种类渔获率均值比结果显示，FPC变化范围在0.03~2.61，其中总渔获率、鱼类、头足类、小黄鱼和绿鳍鱼达到显著水平，建议对上述种类的资源丰度指标年际变化趋势分析时进行数据校正。标准船以近底层种类为调查对象，尤其在捕获经济种类方面表现出优良性能，但对完整生态系统代表性较弱。试验船适合浅水区调查，在深水区由于网口垂直扩张不足，且网位存在上浮现象，难以反映近底层生态系统。  相似文献   

四倍体甜瓜花粉母细胞减数分裂的观察   总被引：2，自引：0，他引：2  

贾媛媛  张永兵  刁卫平  陈劲枫 《中国瓜菜》2009,22(2)

以同源四倍体甜瓜为材料,采用常规压片法研究花粉母细胞减数分裂行为。结果表明:同源四倍体甜瓜花粉母细胞减数分裂过程与二倍体类似,但有其特殊性。主要表现在:粗线期观察到有6.7%的细胞出现双核;终变期的四倍体染色体构型较复杂,有二价体、多价体、三价体和单价体;中期I和中期II有赤道板外染色体;后期I和后期II出现染色体桥和落后染色体;四分体时期出现二分体、三分体和多分体。花粉母细胞减数分裂的异常是同源四倍体甜瓜育性低的细胞学原因。  相似文献   

Meiotic chromosome behavior in allotriploid cultivar of Lifium hybrids.     

《北京林业大学学报》2012,34(2)

采用细胞遗传学方法,对Longiflorum×Asiatic系列异源三倍体百合‘Bonsoir’（2n=3x=36）小孢子母细胞减数分裂进行了研究和分析。结果显示,有64．31％的花粉具有活力,且有活力的花粉大小范围在986．33-3491．68μm2之间,并呈双峰分布。形成败育花粉的主要原因如下：高度不规则的染色体配对、落后染色体、染色体桥、不均等分离、微核等现象。另外,减数分裂中期Ⅱ纺锤体的异常定向导致了末期Ⅱ二分体和三分体的形成,产生未减数的配子,如融合纺锤体和三极纺锤体;但平行纺锤体和垂直纺锤体不参与未减数配子的形成。一些小孢子母细胞在胞质分裂过程中未形成细胞板,导致单分体的形成以及二分体和三分体的增加,提高了未减数配子的颛率。通讨对小袍子发毕讨稃中各种观象的观察．对异源=倍体百合存畜种申的府阳讲行讨论．  相似文献   

植物生长调节剂与母株年龄对芫花扦插繁殖的影响     

余拱鑫  郭赛谦  郭百川  张振英  朱晓兵  郝雪英  刘胜猛 《现代农业科技》2022,(20)

为探索芫花扦插繁育技术,加快芫花繁育进程,以芫花一年生枝条为材料,研究了植物生长调节剂不同浓度和母株树龄对芫花扦插的影响。结果表明,芫花插穗生根率以1000mg.L^-1生长调节剂(IBA：NAA=1:1,二者总浓度之和,下同)处理效果最好,最高可达84%;高浓度调节剂(750mg.L^-1以上)处理时,生根数随着浓度增加而减少,但750mg.L^-1与1000mg.L^-1处理差异不显著;2年生母株插条的生根率和生根数均要大于5年生母株的,且差异显著;调节剂浓度和母株年龄对根长的影响很小。  相似文献   

脱毒马铃薯扩繁技术初探   总被引：1，自引：0，他引：1  

杨明君  樊民夫  李久昌  张立平  鲁喜忠 《中国马铃薯》1995,(4)

本试验以早熟品种东农３０３、中熟品种系薯１号和晚熟品种晋薯７号为试验材料，采用Ｌ１２（４×３￣２）正交试验法，分室内和室外两组同时进行试验，结果表明，出芽天数随着温度的上升而减少；大薯块出芽数极显著高于中小薯块；出芽数则随着掰芽次数的增加而减少；系薯１号的出芽数明显高于晋薯７号，与东农３０３差异不显著．产量结果表明，主因素为品种；其次为薯块大小；掰芽次数间差异不显著；母薯则极显著高于掰芽次数．综合结果分析，脱毒马铃薯掰芽扩繁是一项节省种薯，提高繁殖系数的有效措施；以选择适宜当地种植的高产高效和大薯块掰芽为好；三次掰芽扩繁移栽和母薯直播是可行的马铃薯扩繁技术措施．  相似文献