Correlation between hydrolytic enzyme activities measured in bean seedlings afterTrichoderma koningii treatment combined with pregermination and the protective effect againstPythium splendens     

Alba Marina Cotes  Philippe Lepoivre  Jean Semal 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(5):497-506

An experimental protocol consisting in the colonisation of pregerminated bean seeds dressed withTrichoderma sp. was used in order to study the mechanisms correlated with the protective effect againstPythium splendens. Seed dressed with TH-11 (T. koningii) for 24 h presented a higher protective effect and a higher level of seed colonisation as compared to those dressed with TH-13 (T. longibranchiatum). The levels of seed coat colonisation by TH-11 and TH-13 was shown to be correlated with the carboxymethylcellulase activity, as measured in the seed coats retreived from germinating dressed bean seeds. The seed coat colonisation was also associated with an increased activities of endo-1,3--glucanase and endochitinase measured in seed extracts, and an inhibitory effect of seed extracts onPythium sporangia germination. Pretreatment of TH-13-dressed seeds with a commercial cellulase improved all parameters mentioned above, thus suggesting a role of cellulase activity in the colonisation process and the linked protective effect. The possible role of hydrolytic enzymes in the protective effects is discussed.  相似文献   

香菇干制微机监控系统研究     

赵武奇  国培光 《吉林农业大学学报》1995,17(3):74-78

本文研究香菇干制过程的计算机控制。在研制了系统硬件之后,根据实验结果,确定了控制对象的广义数学模型,用飞升曲线法求取模型中各参数。用计算机仿真技术对几种常用的算法进行比较,得出了采用大林算法的控制方案。  相似文献   

Prospects for improving potato crop protection against aphid vectors     

Y. Robert 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(Z2):37-45

Conventional ways to control aphid vectors on potato crops rely essentially on cultural and chemical methods. The extensive use of insecticides, too often applied regardless of real needs and consequences, has resulted in more and more failures in both controlling aphids and virus spread. This paper stresses the need to introduce more rationale in the operation of existing methods by improving the efficiency of some of them like forecasting systems, to assess the potential of others like fertilization and semiochemicals and to put most efforts on resistant cultivars so that integrated pest management can be operated in the near future.  相似文献   

Control of Fusarium wilt in carnation grown on rockwool by Pseudomonas sp. strain WCS417r and by Fe-EDDHA     

R. Van Peer  A. J. Van Kuik  H. Rattink  B. Schippers 《European journal of plant pathology / European Foundation for Plant Pathology》1990,96(3):119-132

In carnations grown on rockwool disease incidence of fusarium wilt caused byFusarium oxysporum f.sp.dianthi (Fod) was reduced when Fe-EDDHA instead of Fe-DTPA was used as iron source in the nutrient solution. Addition ofPseudomonas sp. strain WSC417r intensified this reduction in the cultivar Pallas, moderately resistant to Fusarium, but not in the susceptible cultivar Lena. Treatment of plants with Fe-EDDHA instead of Fe-DTPA as iron source resulted in higher numbers and percentages on the roots, ofin vitro antagonistic fluorescent pseudomonads. However, differences were only significant at 56 days after planting for cv. Lena and at 14 and 28 days after planting for cv. Palas. Both chelators, at different concentrations, had no effect on root colonization by eitherPseudomonas sp. strain WCS417r orFod strain WCS816. However, when coinoculated, reduced numbers of propagules ofFusarium were found at concentrations of Fe-EDDHA lower than 10^–5 M.Higher concentrations of the siderophore fusarine produced byFod strain WCS816 were demonstrated when Fe-EDDHA instead of Fe-DTPA was used as iron source in culture media. At equal concentrations, no such differences were found in the amount of siderophore produced by WCS417r. Germ tube length ofFod was less with Fe-EDDHA than with Fe-DTPA. The reduction of germ tube length was stronger when the purified siderophore of WCS417r was added in excess to the culture media with Fe-EDDHA than those with Fe-DTPA. Therefore, the observed reduction of germ tube growth can not completely be explained by iron deprivation. It appeared that EDDHA exhibited a toxic effect for conidia ofFod strain WCS816 as well.we conclude that the observed disease reduction by Fe-EDDHA is a consequence of a limitation of iron availability forFod. This limitation is possibly intensified by the increase in number or percentage of antagonistic fluorescent pseudomonads that strongly compete for iron. The additional effect after bacterization withPseudomonas strain WCS417r in Fe-EDDHA treated carnations of cv. Pallas is likely to be due, at least partly, to a direct competition for iron between the siderophores ofFod strain WCS816 and ofPesudomonas sp. strain WCS417r.Samenvatting Verwelkingsziekte in anjers op steenwol, veroorzaakt doorFusarium oxysporum f. sp.dianthi (Fod), werd gereduceerd indien het ijzer-chelaat Fe-EDDHA in plaats van Fe-DTPA werd toegevoegd aan de nutriëntenvloeistof. Bacterisatie metPseudomonas sp. stam WCS417r had een additioneel effect bij de matig resistence cultivar Pallas maar niet bij de vatbare cultivar Lena. Toevoeging van Fe-EDDHA in plaats van Fe-DTPA aan planten als ijzerbron resulteerde op de wortels in hogere aantallen en percentages fluorescerende pseudomonaden, diein vitro antagonistisch waren ten opzichte vanFod. De verschillen waren echter alleen significant 56 dagen na planten voor de cultivar Lena en 14 en 28 dagen na planten voor de cultivar Pallas. Beide chelaten vertoonden bij verschillende concentraties geen effect op de kolonisatie van de wortel door beide microorganismen. Echter, wanneer beide micro-organismen gezamelijk werden toegevoegd nam de wortelkolonisatie doorFod stam WCS816 af bij concentraties lager dan 10^–5 M Fe-EDDHA. Er werd meer van het siderofoor fusarine doorFod stam WCS816 geproduceerd bij concentraties lager dan 10^–4 M Fe indien Fe-EDDHA in plaats van Fe-DTPA als ijzerbron aan het cultuurmedium was toegevoegd. Er werd geen effect van beide chelaten gevonden op de siderofoorproduktie door WCS417r. Indien een overmaat van het gezuiverde siderofoor van WCS417r werd toegevoegd aan Fe-EDDHA werden een sterkere afname van de kiembuislengte gevonden dan toevoeging aan Fe-DTPA. De reductie van de kiembuislengte bleek niet volledig verklaard te kunnen worden door een afname van de ijzerbeschikbaarheid. Het chelaat EDDHA heeft ook een toxisch effect op conidiën van fusarium.Wij concluderen, dat de waargenomen reductie van de verwelkingziekte door Fe-EDDHA een gevolg is van de afname van de ijzerbeschikbaarheid voorFod. Dit wordt waarschijnlijk versterkt door de ontwikkeling van een antagonistische, fluorescerendePseudomonas-populatie die sterk concurreren om ijzer. Het additioneel effect dat door bacterisatie metPseudomonas sp. WCS417r van de met Fe-EDDHA behandelde matig resistante anjers (Pallas) werd verkregen is voor een deel het gevolg van een directe concurrentie om ijzer tussen de sideroforen vanFod stam WCS816 en vanPseudomonas sp. stam WCS417r.  相似文献   

草坪阔叶杂草的防除技术研究   总被引：1，自引：0，他引：1  

王海霞 《四川草原》2005,(7):36-38

2001￣2002年,应用百草敌、2,4-D丁酯乳油、2甲4氯丙酸及混合药剂对西宁郊区石头磊实验地草坪杂草进行防除实验。结果表明:百草敌、2,4-D丁酯乳油及混合物药剂I对几种主要杂草防除效果比较好,与对照相比较,30d能达到100%,且两种混剂有增效作用,扩大了除草剂的使用范围。  相似文献   

Parasitoid community of the loreyi leaf wormMythimna (Acantholeucania) loreyi: Novel host-parasitoid associations and their efficiency in the eastern mediterranean region of Turkey     

Erdal Sertkaya  Ahmet Bayram 《Phytoparasitica》2005,33(5):441-449

The loreyi leaf worm,Mythimna (Acantholeucania) loreyi Duponchel (Lepidoptera, Noctuidae), is a pest of gramineous crops and causes significant economic damage to maize. In field surveys on maize to determine the parasitoid community and its impact on the pest in the eastern Mediterranean region of Turkey, nine parasitoid species were found associated with immature stages ofM. loreyi: The hymenopteran (Braconidae and Ichneumonidae) parasitoidsCotesia (=Apanteles) ruficrus (Haliday),Chelonus oculator Panzer,Meteorus ictericus Nees,Hyposoter didymator (Thunberg),Sinophorus sp.; and the dipteran (Tachinidae) parasitoidsPseudogonia rufifrons Wiedeman,Exorista rossica Mesnil,Gonia picea (Robineau-Desvoidy) andLinnaemya vulpina (Fallen) — the last three recorded for the first time as parasitoids ofM. loreyi in Turkey.C. ruficrus was the dominant parasitoid species, being recovered from 38.5% of the larvae collected and was also the most prevalent species, existing in 91.0% of the fields in whichM. loreyi was found. Total parasitism levels achieved by braconid species was 41.4%, by ichneumonid parasitoids 4.8%, and by tachinid parasitoids 1.9%. In a separate field experiment, seasonal population fluctuations and natural efficiency ofC. ruficrus onM. loreyi were found to be 35.1% and 42.4%, respectively. Population levels ofC. ruficrus were closely related to fluctuations in the population ofM. loreyi, with parasitism ranging between 0 and 77.3% during the study. http://www.phytoparasitica.org posting Aug. 28, 2005.  相似文献   

A grower-friendly method to transfer predacious mites to commercial orchards     

N. J. Bostanian  J. Lasnier  G. Racette 《Phytoparasitica》2005,33(5):515-525

The establishment of predacious mites in commercial orchards may be accelerated by the transfer of pruned wood in winter and summer from donor orchards to release orchards. Following winter pruning, 3-year-old and older wood is collected and transported as soon as possible in bundles to a release orchard for distribution. If the release orchard is composed of dwarf trees, then one or two bundles of 5 kg each are placed vertically at the base of the trunk of every tree in the block (0.5 to 1 ha); if the trees are of standard size, then four or five bundles used. Following summer pruning, annual shoots and suckers are distributed immediately in a release orchard composed of dwarf trees by placing 12–15 branches on the foliage of fruit-bearing branches; if the release orchard is composed of standard trees, then 50 branches are used. The pruned wood should have 20–25 leaves and not less than one predator per leaf. The release orchard should have a light infestation (two or three mites per leaf) of pest tetranychids. These phytophagous mites would serve as food and help establish the predators. The release orchard grower should develop a pest management program based on the same groups of pesticides used in the donor orchard. http://www.phytoparasitica.org posting Aug. 31, 2005.  相似文献   

黑木耳烘干控制系统的研究     

齐怀琴  李春林 《中国食用菌》2005,24(6):49-51

黑木耳烘干控制系统，采用压缩式热泵，AT89C51单片机、SHT75型温湿度传感器、加热器等组成温湿度控制电路。控制干燥室内的温湿度，完成对干燥室内的黑木耳进行低温、高效率的去湿干燥。  相似文献   

我国防沙治沙科研的突破口初探-以河西走廊沙区为例   总被引：2，自引：3，他引：2  

常兆丰 《干旱区研究》2003,20(1):76-80

河西走廊的防沙治沙科研在我国广大沙区具有代表性。河西走廊防沙治沙科研存在的主要问题是 :⑴宏观战略研究薄弱 ,研究缺乏系统性。主要表现在 :治沙措施散件得不到优化组合 ,其功能得不到充分发挥 ;研究客体之间互相割裂 ,缺乏从总体上控制沙漠化的研究 ;农业开发与生态资源保护的结合点问题没有解决 ;研究课题重复。⑵散件成果多属定性结论 ,缺乏操作性。运用系统科学的思想方法是治沙科技发展的突破口 :只有运用系统科学的思想方法才能科学处理生态资源保护、生态环境建设和资源开发利用三方面的关系 ,才能实现各种防沙治沙措施的优化配置 ,才能实现治理结果的持续稳定。运用现代数学方法建立沙区生态环境综合治理数学模型才能科学处理多系统的复杂关系。现代数学方法是系统科学的主要方法。运用系统科学的思想方法和现代数学方法是治沙科技发展必须达到的 ,是治沙科技发展的突破口。  相似文献   

The urbanization of wildlife management: Social science, conflict, and decision making     

Michael E. Patterson  Jessica M. Montag  Daniel R. Williams 《Urban Forestry & Urban Greening》2003,1(3):171-183

Increasing urbanization of rural landscapes has created new challenges for wildlife management. In addition to changes in the physical landscape, urbanization has also produced changes in the socio-cultural landscape. The greater distancing from direct interaction with wildlife in urbanized societies has led to the emergence of a culture whose meanings for wildlife are less grounded in the utilitarian/instrumental orientation of rural agrarian systems. Urban perspectives on wildlife are comprised of more highly individualized emotional/symbolic values. This shift creates two problems with respect to managing wildlife in an urbanizing landscape. First the increased diversity in values and meanings increases the likelihood for social conflicts regarding wildlife management while at the same time making socially acceptable resolutions more intractable. This in turn requires fundamental changes in decision-making paradigms and the research approaches used to inform decision making. Second, as remaining rural communities feel the pressures of urbanization, wildlife conflicts become conflicts not just over wildlife but conflict over larger socio-political concepts such as equity, tradition, private property rights, government control, power, and acceptable forms of knowledge. This paper examines the wildlife management implications of changes associated with increasing urbanization and employs two case studies to illustrate these issues. First a study of a controversy over urban deer management provides insights into how to map conflicting values and search for common ground in an urban culture with increasingly individualistic values for wildlife. Specifically, the analysis illustrates that common ground may, at times, be found even among people with conflicting value systems. The second case study examined a ranching community faced with predator reintroduction. This case study illustrates tensions that occur when the community of interest (i.e. a national public) is broader than the community of place in which the problem occurs. In this latter situation, the debate centers around more than just different views about the rights of animals. It also entailed the rights of individuals and communities to decide their future. The conclusion discusses the need for wildlife institutions to adapt their underlying decision making philosophy including the way science is integrated into decision making processes in light of the changes in social context caused by urbanization.  相似文献