Disease eradication and propagation of the initial seed potato material in Estonia     

K. Kotkas  V. Rosenberg 《Potato Research》1999,42(3-4):577-583

Summary The EVIKA Research Centre has developed a disease eradication system for the initial material of seed potato, which consists of 1. Selection of the initial material for eradication, plant thermotherapy, meristem tip cultivation and testing for viruses; 2. Re-eradication (thermotherapy of test-tube plants, cultivation of meristem tips, testing for viruses, testing of varietal quality and yield of disease-free meristem clones, and the selection of meristem clones with best varietal characteristics; 3. Renewing of the initial material (all processes as above, but the initial material is selected from the seed potatoes grown for at least 3 years in the field). Field trials were conducted after the second cycle of eradiaction to determine whether the plantlets were true-to-type and to assess the yield, disease resistance and tuber dry matter. Recently we have also started in vitro testing of meristem plants resistance to late blight, hoping that this approach will improve the selection efficiency. Propagation and growing of the seed tubers consists of 3 main steps: 1. Plantlet propagation in vitro; 2. Greenhouse propagation in plastic rolls; and 3. Planting the first generation tubers in the field. Under our conditions it is the cheapest, simplest and most effective way. Multiplication of the meristem-derived plants is done by shoot tip cuttings in a greenhouse in plastic rolls with peat as the growing medium. The first generation of seed tubers is grown in the field. In our trials plant productivity was affected by the method of multiplication, growing conditions and genotype. The highest yield per hectare was obtained with plants multiplied in plastic rolls. The in vitro plants had more tubers per plant than plants multiplied in plastic rolls. In seed production fields the productivity of plants was more influenced by following our instructions than by multiplication and growing methods. The number of tubers per plant obtained with over 0.5 million plants was 6.5–9.0. In the second generation of seed tubers, grown under equal density, the greater-sized tubers gave more tubers with lower weight than the smaller-sized tubers. Cutting tubers had no effect on the plant development and tuberization.  相似文献   

马尾松轻型基质容器苗造林初效的研究   总被引：2，自引：0，他引：2  

陈辉  洪伟  林光先  蔡启运 《福建林学院学报》1999,19(2):105-109

在苗期分析的基础上,应用试验设计方法,选择了苗期表现不同的容器苗．对不同容器材料、尺寸和基质配比下的容器苗作造林后连续３年跟踪调查,以期从一段时间内考察它们在出圃造林后各处理组合及优良性状的持续效应．通过和裸根苗造林效果的对比试验,进行综合效益分析,在统计分析的基础上,确定最佳造林初效时容器材料、容器尺寸和基质配比的组合  相似文献   

温度变化对七带石斑鱼早期发育及开口摄食的影响   总被引：1，自引：0，他引：1  

刘莉  陈超  孔祥迪  李炎璐  于欢欢  翟介明  庞尊方 《海洋渔业》2017,39(4)

观察比较了9个温度梯度(13、15、17、19、21、23、25、27、29℃)对七带石斑鱼(Epinephelus septemfasciatus)受精卵孵化时间、孵化率和畸形率的影响。用在(21±0.5)℃条件下孵出的健康仔鱼进行耐饥饿和摄食实验,实验温度处理设两种方式:一、处理温度始终保持不变;二、将温度在处理48 h后统一调节至21℃。实验期间,每天统计仔鱼死亡数,测定不投饵条件下的存活指数(SAI),并观察仔鱼投饵后的开口摄食情况及其形态发育状况。结果表明:1)受精卵孵化的最适温度范围为17~23℃,当温度低于13℃或高于27℃时,受精卵不能孵化。21℃时,受精卵孵化率最高,为(93.67±1.52)%;而畸形率最低,为(1.06±1.06)%。当温度低于或高于21℃时其孵化率降低,而畸形率升高;2)在13~28℃范围内,初孵仔鱼的SAI值随着温度的上升先升高后逐渐降低,21℃时的SAI值最高,为(20.26±0.44)%。各组温度保持不变时,13℃和27℃的SAI值分别为(2.18±0.01)%、(8.47±0.28)%;调整一致后分别为(6.90±0.44)%、(13.30±0.31)%。温度调节组与不调节组相比,其SAI值明显提高。温度调节后,每个梯度组的畸形率也出现了不同程度的降低;3)不同温度处理的仔鱼开口摄食存在差异。21℃时,仔鱼的初始摄食率和饱食率分别可达80.0%和40.0%。随着温度偏离21℃,摄食率和饱食率均逐渐降低。温度调节恢复组的仔鱼摄食情况改善明显,其中17℃不变和恢复组对比变化最为明显:当保持17℃不变时仔鱼的摄食率和饱食率分别为20.0%、13.3%,而处理48 h后恢复到21℃后,两者分别提高到66.7%和33.3%,分别提高了2.3和1.5倍。  相似文献   

Improved cadmium sorption isotherms by the determination of initial contents using the radioisotope 109Cd     

Bettina Schug  Rolf‐A. Düring  Stefan Gth 《植物养料与土壤学杂志》2000,163(2):197-202

Cadmium (Cd) sorption isotherms were estimated by two different analytical approaches to assess the influence of initial Cd concentrations of soil matrix on the sorption of added Cd. For the laboratory experiments a heterogeneous set of samples was collected to include a wide range of different initial Cd concentrations. Comparison of both analytical methods (conventional analysis, radioanalysis) resulted in a strong conformity of Cd contents in solution at equilibrium. The calculated Cd concentrations in the soil solid phase differ according to the analytical approach for considering the initial contents. The determination of the initial contents by the proposed radioanalytical method with ¹⁰⁹Cd resulted in long linear Freundlich‐isotherms, even in the low concentration range. Thus, radioanalysis seems to be the most suitable method to recognise the initial contents of Cd in soil. EDTA extractable Cd represent the initial concentrations, which are averaged over solid and liquid phase. However, depending on the sorption characteristics of the soil these rates vary. In the investigated set of soil samples 52.3 to 99.3% of Cd must be added to the solid phase.  相似文献   

New tools for studying epidemiology and resistance of grape powdery mildew to DMI fungicides     

Christophe Dlye  Frdric Laigret  Marie-France Corio-Costet 《Pest management science》1997,51(3):309-314

Using a Random Amplified Polymorphic DNA (RAPD) assay, we investigated the genetic polymorphism existing among 62 European isolates of the grape powdery mildew fungus (Uncinula necator [Schw.] Burr.). Isolates overwintering as mycelium in buds were genetically distinct from isolates overwintering as ascospores, suggesting the existence of two genetically isolated powdery mildew populations, and consequently of two independent sources of inoculum in the vineyard. Isolates resistant to fungicides inhibiting sterol 14α-demethylation (DMIs) were found in both populations, suggesting that resistance to DMIs may arise independently in the two powdery mildew populations. A PCR assay targeting the gene encoding U. necator 14α-demethylase has been developed which will permit an early, specific detection of U. necator infections, and may be useful for spraying programmes. ©1997 SCI  相似文献   

储藏温度与初始含水率对稻谷和糙米食用品质的影响     

陈坤杰  梁静  蒋维银  张季伟  於海明 《农业机械学报》2022,53(9):390-398

以产于江苏省东台市的南粳9108为研究对象,测定了3种含水率（12.10%、14.16%和16.34%）的稻谷和糙米,在低温（8℃）、准低温（15℃）及室温（20~25℃）3种储藏条件下的含水率、脂肪酸含量、食味值和直链淀粉含量4个食用品质指标的变化,分析比较了在245d的储藏期内,稻谷和糙米食用品质指标的变化规律。结果表明,在储藏前,偏高含水率样品的食用品质优于正常和偏低的样品。但随着储藏时间的延长,稻谷和糙米的含水率和食味值均逐步降低,而脂肪酸含量和直链淀粉含量则出现不同程度的上升,初始含水率、储藏温度和时间对脂肪酸含量、食味值和直链淀粉含量均有极显著的影响（P＜0.01）。在不同的储藏温度下,不同含水率稻谷和糙米的食用品质都随着储藏时间的延长而逐步降低。其中,较高含水率的样品在较高储藏温度下品质下降的程度更高,而且糙米食用品质下降的程度高于稻谷。另外,试验结果还显示,在低含水率条件下（12.1%）,在不同储藏温度下稻谷和糙米食用品质变化都很小,表明在较低含水率下将水稻以稻谷的形式进行储藏,有利于保持食用品质。  相似文献   

初始含水率和降雨能量对黑土团聚体溅蚀特征的影响     

张转敏  王彬  饶伟  王文刚 《水土保持学报》2024,38(2):68-75

[目的] 为明晰降雨能量和初始含水率对土壤团聚体溅蚀过程机制的影响。[方法] 选取东北典型耕层黑土为研究对象,通过人工模拟降雨试验,探讨不同初始含水率、降雨能量和团聚体初始粒径的团粒溅蚀特征。[结果] (1)4种初始粒径黑土团聚体的溅蚀量均在初始含水率4%时最大,其中初始粒径＜0.25 mm团聚体溅蚀量是相同降雨能量下各粒径团聚体溅蚀量的1.21~5.50倍。随初始含水率的增加各初始粒级团聚体溅蚀量呈减小趋势,而初始含水率＞25%后则呈增大现象。(2)4种初始粒径黑土团聚体的溅蚀量均随降雨能量的增加而增大。相较于降雨能量305 J/(m²·h)(1 m)条件,当降雨能量增加至909 J/(m²·h)(5 m)时,不同初始粒径团聚体溅蚀量分别增加15.37~20.70(＜0.25 mm),52.30~417.60(0.25~1 mm),51.58~359.36(1~3 mm),68.73~777.99倍(3~5 mm)。不同初始粒径黑土团聚体溅蚀量存在明显的阈值,当降雨能量达到529 J/(m²·h)(2 m)以上时,不同降雨能量梯度下的溅蚀量存在显著差异。(3)降雨能量是影响溅蚀量的关键因素。降雨能量对溅蚀量的直接效应为0.811,存在显著正向影响,且相关程度最高;初始含水率和团聚体初始粒径的直接效应分别为0.193和0.352,存在显著负向影响。[结论] 研究结果可为东北黑土区坡面土壤侵蚀过程机制研究和土壤侵蚀机理模型构建提供科学依据。  相似文献   

不同含水率条件下非饱和边坡的稳定性     

鲜丹  杨仲康 《水土保持通报》2018,38(3):123-129

[目的]试图改进现有初始条件考量方法,重点分析不同初始含水率条件下降雨入渗对边坡稳定性的作用机制,为滑坡预警提供参考。[方法]以甘肃省天水市廖集村滑坡为例,基于无前期降雨和有前期降雨作用下实测土层含水率结果,将其分别定义为天然和湿润状态,作为初始条件建立渗流与应力的流—固耦合物理力学模型。[结果]天然状态下,非饱和入渗迅速,但入渗仅局限于浅表层1—2m,稳定系数在入渗初期显著下降,但随着下渗的停滞而缓慢变化,往往形成浅表层滑坡;湿润条件下,土体持水缓慢,但能下渗到3—4m以下的较深部位,随着入渗深度的增大,土体软化作用加强,形成深部滑坡。所以,土体干燥状态时,进行7d的雨量预警是有效的防灾方法。对于连阴雨天气,土层较湿润,要注重对滑坡体4m以下部位孔隙水压力和坡脚位移形变的监测。[结论]土体初始条件对非饱和入渗和稳定性变化过程具有显著影响,是降雨触发型滑坡稳定性分析中不可忽略的因素。  相似文献   

油菜菌核病发生流行与菌源量、气候因子关系分析及病情预测模型的建立     

秦虎强  高小宁  韩青梅  黄丽丽  张吉昌  唐建祥 《植物保护学报》2018,45(3):496-502

为探究油菜菌核病田间发生流行的影响因子并建立病情预测模型,采用田间调查法测定油菜田菌核密度、子囊盘密度、花朵带菌率,并分析了2008—2014年各气候因子与病叶率、成熟期茎秆病株率、病情指数之间的关系。结果显示,田间菌核密度、子囊盘密度、花朵带菌率与病叶率及成熟期茎秆病株率均呈极显著正相关;2月下旬至5月上旬日均气温及2月下旬至4月上旬日均相对湿度、降雨量及降雨天数与各年度成熟期病株率及病情指数均呈显著正相关,而日照时数与各年度成熟期病株率及病情指数均呈极显著负相关。以油菜盛花期花朵带菌率作为指标,可预测其田间成熟期病株率;以降雨量(x_2)、降雨天数(x_3)及日照时数(x_4)与各年度成熟期病株率(y_1)及病情指数(y_2)分别建立了预测模型y_1=15.47+0.07x_2+0.42x_3-0.03x_4和y_2=10.36+0.07x_2+0.38x_3-0.03x_4,其拟合度均最高,分别为99.07%和98.43%,可作为油菜成熟期茎秆发病株率及病情指数的预测模型。表明油菜菌核病菌源量和气候因子是影响病害发生流行的关键因子。  相似文献   

Dynamics of post‐harvest pathogens Neofabraea spp. and Cadophora spp. in plant residues in Dutch apple and pear orchards          下载免费PDF全文

J. Köhl  M. Wenneker  B. H. Groenenboom‐de Haas  R. Anbergen  H. M. Goossen‐van de Geijn  C. H. Lombaers‐van der Plas  F. A. M. F. Pinto  P. Kastelein 《Plant pathology》2018,67(6):1264-1277

Post‐harvest diseases of apple and pear cause significant losses. Neofabraea spp. and Cadophora spp. infect fruits during the growing season and remain quiescent until disease symptoms occur after several months in storage. Epidemiological knowledge of these diseases is limited. TaqMan PCR assays were developed for quantification of N. alba, N. perennans, C. malorum and C. luteo‐olivacea in environmental samples. Various host tissues, dead weeds and grasses, soil and applied composts were collected in 10 apple and 10 pear orchards in May 2012. Neofabraea alba was detected in 73% of samples from apple orchards and 48% from pear orchards. Neofabraea perennans was present in a few samples. Cadophora luteo‐olivacea was detected in 99% of samples from apple orchards and 93% from pear orchards, whilst C. malorum was not detected in any sample. In apple orchards, highest concentrations of N. alba were found in apple leaf litter, cankers and mummies, and of C. luteo‐olivacea in apple leaf litter, mummies and dead weeds. In pear orchards, N. alba and C. luteo‐olivacea were found in highest concentrations in pear leaf litter and in dead weeds. Substrate colonization varied considerably between orchards. The temporal dynamics of pathogens was followed in four apple orchards and four pear orchards. In apple orchards the colonization by pathogens decreased from April until August and increased from September until December. This pattern was less pronounced in pear. Knowledge on population dynamics is essential for the development of preventative measures to reduce risks of fruit infections during the growing season.  相似文献