Temperaturansprüche mikroskopischer Bodenpilze aus klimatisch und geographisch verschiedenen Standorten

Temperature demands of microscopic soil fungi from different climatic and geographical sites. . 154 strains of microscopic soil fungi were isolated at 25°C from soils deriving from tropical to alpine climatic zones of the world (SW-Africa, Argentine, Nepal, Canary Islands and W-Germany). Determining their saccharolytic, amylolytic and proteolytic activities on saccharose-, starch- or gelatine-containing agar plates at 5 °C, 15 °C, 25 °C, 35 °C and 43 °C, the activity range as well as the optimal temperature were obtained. The following results were obtained: 1) A clear correlation between the temperature requirements of the fungal flora and the climatic conditions of the site of isolation was observed. 2) The fungal flora of a certain climatic zone was composed of strains of ubiquitously distributed species. Their great adaptability enables them to accomodate themselves to the temperature conditions of each site. 3) A smaller percentage of species was characterised by a small range of temperature variability and therefore depending on a certain climatic zone. Some of these were strict pschychrophilic species, characteristic for alpine and subalpine regions, but others behaved as strict mesophiles observed only in warm regions. 4) Finally from each site of isolation there also could be isolated a certain amount of fungi, whose ecological demands did not or only for a very short time coincide with the bioclimatic conditions of the particular site. Generally, these isolates are able to form resistant spores enabling them to survive unfavourable climatic conditions. .     

Oxygen profiles and methane turnover in a flooded rice microcosm

Summary Dissolved O₂ was depleted within the top 3.5-mm surface layer of flooded rice soil microcosms without plants. In planted microcosms, however, O₂ was detectable down to at least 40 mm in depth. O₂ concentrations in the uppermost soil layers of microcosms with rice plants were higher in the light than in the dark, indicating O₂ production by photosynthesis. The CH₄ emission rates were nearly identical for illuminated and for darkened microcosms, demonstrating that the photosynthetically produced O₂ did not increase CH₄ oxidation in the rhizosphere. In contrast, CH₄ emission rates increased when the microcosms were incubated under an N₂ atmosphere, indicating that transport of O₂ from the atmosphere into the rhizosphere was important for CH₄ oxidation. CH₄ emission under air accounted for only 10%–20% of the cumulative CH₄ production determined in cores taken from the microcosms. Apparently, 80%–90% of the CH₄ produced was oxidized in the rhizosphere and thus was not emitted.     

Analysis of volatile compounds and triglycerides of seed oils extracted from different poppy varieties (Papaver somniferum L.)

Poppy seed oil (Oleum Papaveris Seminis) is used for culinary and pharmaceutical purposes, as well as for making soaps, paints, and varnishes. Astonishingly, hardly anything was yet known about the volatile compounds of this promising comestible. Likewise, there are no current published data about the triglyceride (TAG) composition of poppy seed oils available. In this investigation solid-phase microextraction (SPME) with DVB/Carboxen/PDMS Stable-Flex fiber was applied to the study of volatile compounds of several seed oil samples from Papaver somniferum L. (Papaveraceae). 1-Pentanol (3.3-4.9%), 1-hexanal (10.9-30.9%), 1-hexanol (5.3-33.7%), 2-pentylfuran (7.2-10.0%), and caproic acid (2.9-11.5%) could be identified as the main volatile compounds in all examined poppy seed oil samples. Furthermore, the TAG composition of these oils was analyzed by MALDI-ReTOF- and ESI-IT-MS/MS. The predominant TAG components were found to be composed of linoleic, oleic, and palmitic acid, comprising approximately 70% of the oils. TAG patterns of the different poppy varieties were found to be very homogeneous, showing also no significant differences in terms of the applied pressing method of the plant seeds.     

Root growth and N‐uptake activity of oilseed rape (Brassica napus L.) cultivars differing in nitrogen efficiency

Nitrate‐N uptake from soil depends on root growth and uptake activity. However, under field conditions N‐uptake activity is difficult to estimate from soil‐N depletion due to different loss pathways. We modified the current mesh‐bag method to estimate nitrate‐N‐uptake activity and root growth of two oilseed‐rape cultivars differing in N‐uptake efficiency. N‐efficient cultivar (cv.) ‘Apex' and N‐inefficient cv. ‘Capitol' were grown in a field experiment on a silty clayey gleyic fluvisol near Göttingen, northern Germany, and fertilized with 0 (N₀) and 227 (N₂₂₇) kg N ha^–1. In February 2002, PVC tubes with a diameter of 50 mm were installed between plant rows at 0–0.3 and 0–0.6 m soil depth with an angle of 45°. At the beginning of shooting, beginning of flowering, and at seed filling, the PVC tubes were substituted by PVC tubes (compartments) of the same diameter, but with an open window at the upper side either at a soil depth of 0–0.3 or 0.3–0.6 m allowing roots to grow into the tubes. Anion‐exchange resin at the bottom of the compartment allowed estimation of nitrate leaching. The compartments were then filled with root‐free soil which was amended with or without 90 mg N (kg soil)^–1. The newly developed roots and nitrate‐N depletion were estimated in the compartments after the installing period (21 d at shooting stage and 16 d both at flowering and grain‐filling stages). Nitrate‐N depletion was estimated from the difference between NO ‐N contents of compartments containing roots and control compartments (windows closed with a membrane) containing no roots. The amount of nitrate leached from the compartments was quantified from the resin and has been taken into consideration in the calculation of the N depletion. The amount of N depleted from the compartments significantly correlated with root‐length density. Suboptimal N application to the crop reduced total biomass and seed‐yield formation substantially (24% and 38% for ‘Apex’ and ‘Capitol’, respectively). At the shooting stage, there were no differences in root production and N depletion from the compartments by the two cultivars between N₀ and N₂₂₇. But at flowering and seed‐filling stages, higher root production and accordingly higher N depletion was observed at N₀ compared to N₂₂₇. Towards later growth stages, the newly developed roots were characterized by a reduction of root diameter and a shift towards the deeper soil layer (0.3–0.6m). At low but not at high N supply, the N‐efficient cv. ‘Apex’ exhibited higher root growth and accordingly depleted nitrate‐N more effectively than the N‐inefficient cv. ‘Capitol’, especially during the reproductive growth phase. The calculated nitrate‐N‐uptake rate per unit root length was maximal at flowering (for the low N supply) but showed no difference between the two cultivars. This indicated that the higher N‐uptake efficiency of cv. ‘Apex’ was due to higher root growth rather than higher uptake per unit of root length.     

Sonography of the teat of cattle, sheep and goats in comparison with other methods of diagnostic imaging--a review.]

Beside the clinical examination of udder/teat imaging methods e.g. sonography, radiography and endoscopy allow diagnosis. This publication will give a summary of currently used and potentially usable methods of diagnostic imaging applied to the teat. Advantages and disadvantages of the several methods were compared--as quoted in literature and completed by own experiences.     

Monitoring the Health Status of Pest Populations as a Contribution towards the Establishment of Economic Thresholds

Knowledge of pest population dynamics is required to assess the future abundance of a pest, the losses to be expected and the economic threshold. Mortality of pests caused by diseases can greatly influence their development and a valuable assessment can therefore only be based on healthy individuals. Examples of monitoring the health status are usually taken from the forest and from such insects that develop slowly and allow an assessment of the epizootic before the damaging final instar has been reached (caterpillars, sawflies). In agriculture, the tendency of reducing crop rotation increases the permanence of regulative forces and is consequently favourable. This allows for a more precise prediction on the development of epizootics. Recent observations show that appropriate sampling of aphid populations designed to determine their health status in respect to fungal epizootics can greatly increase the accuracy of the forecast on future trends in population dynamics.