水黄皮叶斑病的成因、严重性及杀菌剂防止

对孟加拉国4个苗圃(IFES、IFESCU、BFRI和ANC)内水黄皮叶斑病症状和严重性进行了调查,结果表明:IFESCU苗圃内叶斑病侵染率及致病指标最高、BFRI次之、ANC最低.与叶斑病相关联的组织从发病植株分离出来,被分离的真菌形成致病性.结果证实胶孢炭疽菌即为致病菌.观察了杧果炭疽病菌丝体生长抑制性并对杀菌剂(Bavistin, Cupravite and Dithane M-45) 有效性和浓度(0.05, 0.10, 0.50, 1.00, 1.50 和 2.00%)进行了鉴定.0.05% Bavistin和Cupravite潜伏8天后,菌丝体生长分别处于最低和最高水平.结果表明:Bavistin杀菌效果最好、Diathane M-45次之,Cupravite对菌丝体生长的抑制作用最低.图1表4参27.     

Gibbsite and halloysite decomposition in strongly acid podzolic soils developed from granitic saprolite of the Bayerischer Wald

The present study reports the occurrence of gibbsite and halloysite in soils derived from granitic saprolites and from glacial deposits formed from granitic saprolites of the Bayerischer Wald (Germany). Both minerals are common in soils of this area. They were formed in the initial stages of weathering, most probably before the Pleistocene and in a warmer climate. Under present conditions halloysite and gibbsite are unstable in the surface soils, as indicated by a decrease in gibbsite concentration towards the surface and by an undersaturation of the equilibrium soil solution with respect to both minerals. It is assumed that the strongly acid conditions and the high concentration of organic compounds in the surface horizons lead to dissolution of gibbsite and possibly to transformation of halloysite to kaolinite.     

The effect of dry conditions on subsequent leakage and rotting of fungal sclerotia

Dried sclerotia of Sclerotium delphinii rotted in moist soil whereas those of Sclerotium cepivorum. Botrytis cinerea and Botrytis tulipae did not. A number of fungi invaded dried sclerotia of S. delphinii in soil, the principal coloniser found in the first sampling being Trichodermu hamatum. Leakage of ¹⁴C compounds from dried labelled sclerotia placed in water was rapid and was little affected by variation in leakage temperature from 1 to 25°C or by prolonging the drying period beyond a day. Leakage from dried sclerotia which were allowed to imbibe water through a small part of their surface was much reduced. Sclerotia which were redried after leakage leaked again when returned to water but with all four fungi the first of three leakage cycles gave the highest ¹⁴C levels. Loss in dry weight in the first leakage cycle was greater with S. delphinii than with the other three fungi and this may be related to the poor survival of dried sclerotia of S. delphinii in moist soil. Substances lost during leakage appear to originate from within sclerotial hyphae rather than from the hyphal free space.     

Processes of collating a European fisheries database to meet the objectives of the European Union Water Framework Directive

Abstract  FIsh Database of European Streams, a common database for the FAME project, was merged using existing data on electric fishing and environmental data. FIsh Database of European Stream is a relational database with eight tables. Metrics based on classification of fish species into guilds were calculated, and provided in separate tables. FIsh Database of European Stream contained information about 150 freshwater fish species, from 12 countries, 17 ecoregions, 40 main river regions, 2651 rivers and 8228 sites. Examples of data coverage and use are given. Relationships between environmental variables were illustrated using principal component analysis, which resulted in three environmental components – latitude, size and altitude. Environmental component scores were correlated with fish metrics used in the European Fish Index. Results exemplify how fish guilds reflect gradients in environmental variation. Benefits and problems concerning standardisation and data availability at the global level are discussed.     

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