Einfluß einer abgestuften Wasserversorgung auf CO2-Assimilation,Transpiration, Substanzproduktion und Wasserverbrauch vonAvena sativa

Zusammenfassung Gefäßkulturen von Hafer in Sand und Erde mit abgestuftem, jeweils gleichbleibend gehaltenem Wasserangebot von 100, 75, 50, 30 und 15% der Boden wasserkapazität ergaben die höchsten Erträge an Gesamttrockenmasse in der Regel bei voller Wassersättigung des Bodens in Verbindung mit gleichzeitig maximalem Wasserverbrauch (bestimmt durch tägliches Wägen der Gefäße). Abnehmende Wasserversorgung verringerte auch Trockenmasse und Wasserverbrauch der Pflanzen. In trockenem Boden und bei reichlicher Wasserzufuhr entwickelte sich die Wurzelmasse im Vergleich mit den oberirdischen Organen stärker als bei mittlerer Bodenfeuchtigkeit. Klimatische Einflüsse, Aussaatzeit und Witterung sowie die Bodenart modifizierten die vom Wasserzustand des Bodens ausgehenden Wirkungen auf Trockenmasseproduktion und Wasserverbrauch, z. B. wurde bei Sommeraussaat gegenüber der Frühjahrsaussaat die Blattentwicklung bedeutend gefördert.Mit registrierenden Infrarot-Gasanalysatoren wurden Tagesgänge von CO₂-Aufnahme, Nachtatmung und Transpiration unter natürlichen Bedingungen gemessen. Bei trockenem Boden war die photosynthetische Leistung der Pflanzen zu Beginn ihrer Entwicklung deutlich gehemmt; sie steigerte sich allmählich und war später merklich größer als bei hohen Wassergaben. Die Transpiration verlief im allgemeinen gleichsinnig wie die Netto-Assimilationsrate, wurde jedoch auch nachts meist auf einer gewissen Höhe fortgesetzt. Die Nachtatmung der sehr trocken gehaltenen Pflanzen war gegenüber den anderen Wasserstufen meist erhöht. Die Trockenkulturen zeigten einen größeren Lichtbedarf; der Lichtkompensationspunkt wurde gewöhnlich erst bei höherer Beleuchtungsstärke erreicht als bei guter Wasserversorgung. Daraus wird auf erhöhten Energiebedarf der sehr trocken kultivierten Pflanzen geschlossen. Das Verhältnis zwischen CO₂-Aufnahme und Transpiration wurde durch unterschiedliche Bodenwasserversorgung meist nur wenig beeinflußt. Die Ergebnisse der CO₂-Assimilationsmessungen stehen im großen und ganzen mit dem wöchentlich festgestellten Trockensubstanzgewinn in Einklang.

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Summary Cultures ofAvena sativa L. grown in pots with sand or garden soil with a graduated, in each case fairly constant water supply of 100, 75, 50, 30, and 15% of field capacity yielded maximum total dry weight, as a rule, in fully water-saturated soils combined with maximum water consumption (measured by daily weighing). Decreasing water supply reduced dry matter production and water consumption of plants. In dry soil and at high degrees of water saturation roots developed more dry matter in comparison to the shoots than at medium soil moisture. Results in dry matter production and water consumption, as caused by water relations in soil, are modified additionally by climatic factors, sowing date and weather, and soil type, e.g. sowing in summer considerably favoured leaf development, compared with the spring seed.Daily courses of CO₂-uptake, night respiration and transpiration were registered by infrared-gasanalyzers. In very dry soil photosynthetic activity of plants was distinctly hampered during the first weeks of development; it gradually increased, and at a later stage photosynthetic activity was markedly higher than at abundant water supply. In general transpiration followed the net assimilation rate, it was continued, however, even over night on a certain level. Night respiration of plants growing in dry soil was higher in relation to the other water stages. Those plants, too, required more light for dry matter production; their light compensation point arrived at higher light intensity than under abundant water supply. This behaviour seems to indicate higher energy requirement of plants distinctly influenced by water stress. Relations between CO₂-uptake and transpiration were but slightly influenced by different soil water level. Results of gas exchange measurements on CO₂-assimilation agreed, as a rule, with the weekly dry matter measurements by weighting.

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Versuche zur Verwendung von „Ersatzwirten” bei Laborzuchten der Zehrwespen Micropleetron fuscipennis Zett. (Chalcididae,Eulophinae) und Pteromalus alboannulatus Ratz. (Chalcididae,Pteromalinae)

Zusammenfassung 1. Die Weibchen der ChalcididePteromalus alboannulatus Ratz. sind in Laborzuchten außer an Puppen der Kieferneule(Panolis flammea Schiff.) erfolgreich auch zur Fortpflanzung an Puppen vonBupalus piniarius L.,Ellopia prosapiaria L.,Hematurga atomaria L.,Boarmia bistortata Goeze undSphinx pinastri L. zu bringen.2. Zuchten der ChalcidideMicroplectron fuscipennis Zett. lassen sich bei Mangel anDiprion-Kokons mit Hilfe der Kokons vonLygaeonematus abietum Htg., besser mit solchen vonLygaeonematus wesmaeli Tischb. weiterführen. Im Freilandversuch ergibt sich jedoch eindeutig eine Bevorzugung derDiprion-Kokons.Neuerdings auch:Dahlbominus.Neuerdings auch:Dirhicnus.     

Spatial distribution of earthworms [Lumbricidae] in recultivated soils of the Rhenish lignite‐mining area,Germany

The spatial distribution of earthworms was studied by means of combined formalin expulsion and hand sorting in three arable fields of the Rhenish lignite‐mining area that differed in their recultivation age (6, 12, 24 yr). In addition, pH and the spatial distribution of penetration resistances were measured to see if they are corresponding with the distribution of earthworms. Already the 6 yr old field had a rich population of endogeic, anecic, and epigeic earthworms (119 ind. m^–2, 48 g m^–2, 6 species). This quantity was similar to the 24 yr old site. The 12 yr old field was only sparsely populated by earthworms (5 ind. m^–2, 5 g m^–2, 3 species). In the 6 yr old field, the spatial distribution pattern showed a center of maximal earthworm abundances, corresponding to the distributional pattern of penetration resistances. In the old field (24 yr), the species varied in their spatial distribution, and there was no correspondence with the distribution of penetration resistance. In general, the penetration resistance at the youngest site was clearly lower than at the two older sites. The earthworm population in the 6 yr old field can be explained by cocoons contained in the dumped material. A calculation using literature data on earthworm‐population dynamics shows that a founding population of 400–600 reproductive individuals per hectare and a continuity of favorable growth conditions during the time of soil management is necessary for the development of the situation found at the 6 yr old site in this study.     

Mikrosondenuntersuchungen an unterschiedlich stark mit Schwermetallen belasteten Böden. 2. Gehalte an Schwermetallen und anderen Elementen in Huminstoffaggregationen,Streustoffen und Holzkohlepartikeln

Electron microprobe studies on soil samples with varying heavy metal contamination. 2. Contents of heavy metals and other elements in aggregations of humic substances, litter residues and charcoal particles EMA point analysis show that the organic matter constituents of heavy metal contaminated soils are highly enriched with heavy metals. The maximal trace element accumulation were for Cu up to 13,000 mg/kg, for Zn up to 48,000 mg/kg, for Cd up to 2,100 mg/kg and for Pb up to 193,000 mg/kg. The affinity for the accumulation of the different heavy metals in aggregations of humic substances can be described by the sequence Cu > Pb ? Cd > Zn ? Ni > Co. In very strongly acidified humic top soil horizons the Pb and Cd accumulation in the organic matter constituents is in competition with the accumulation in Fe and Mn oxides. The heavy metal contents (especially of Cu) of the organic matter are often correlated with the content of organically bound calcium. The EMA results also show that high heavy metal amounts occur in combination with Ca-accumulations in the epidermis and the outer bark parenchym of decayed roots. EMA point analysis of the interior of fungus sclerotias show that sclerotias can contain high amounts of heavy metals, in particular lead (up to 49,700 mg Pb/kg). From statistical results of EMA point analysis follows that lead and other heavy metals attached to humic substances are not only bound as metal organic complexes but also as organic metal phosphate complexes. Also charcoal particles of polluted soils contain high amounts of heay metals. The accumulation affinity is quite similar to that of humic substances.     

Dose measurement in small animal radiology: how intense is the influence of distance and position of the investigator in relation to the patient?

Radiation exposure of body parts of persons, needed to restrain small animal during the examination, varies depending on the distance and position in relation to the patient, the region investigated, and the exposure settings applied. The aim of the study was to quantify the effects of these factors on the ambient dose. The dosimeter was positioned with varying distance from the direct beam (from 30 to 150 cm) and on different level above the floor (55 cm, 85 cm, and 150 cm. The study consisted of two parts. In the first part a plastic water tank (thickness: 18 cm) was used as source of scatter radiation. Different exposure settings (77 kVp; 20 - 10 - 5 - 2.5 - 1.25 mAs) were applied. In the second part dose was measured during the examination of the abdomen of a large dog (thickness: 18 cm; 77 kVp, 20 mAs) and of the skull of a cat (thickness: 6 cm; 55 kVp, 20 mAs). At the level of the patient (85 cm above the floor) the dose decline relative to the distance followed a quadratic function. In the series "abdomen-dog" the mean dose values ranged from 51.6 microSv (30 cm distance) to 1.02 microSv (150 cm distance). The corresponding doses for the series "skull-cat" were 0.98 microSv and 0.02 microSv, respectively. Comparably lower doses were measured on the lines along the table, when non-irradiated parts of the body were located between the exposed patient volume and the dosimeter. At 150 cm above the floor higher doses were observed relative to the doses at the level of the table. The following conclusions can be drawn: (1.) Depending on the target volume the ambient dose varies in a wide range. (2.) An increase of the distance of only few centimetres is reducing exposure considerably. Therefore persons should make use of it whenever this is possible. (3.) Persons should stand on the short sides of the table while fixing the patient. (4.) Head and neck are relatively highly exposed. Methods to protect the thyroid gland and the eye lens are indicated. (5.) Since different exposure levels can be applied in digital radiography, the range of dose levels is rather wide. Therefore strict dose discipline (e.g. by use of exposure tables and dose indicators) is necessary to avoid continuing overexposure.     

Identification of enterodiol as a masker for caffeine bitterness by using a pharmacophore model based on structural analogues of homoeriodictyol

Starting from previous structure-activity relationship studies of taste modifiers based on homoeriodictyol, dihydrochalcones, deoxybenzoins, and trans-3-hydroxyflavones as obvious analogues were investigated for their masking effect against caffeine. The most active compounds of the newly investigated taste modifiers were phloretin, the related dihydrochalcones 3-methoxy-2',4,4'-trihydroxydihydrochalcone and 2',4-dihydroxy-3-methoxydihydrochalcone, and the deoxybenzoin 2-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxyphenyl)ethanone. Starting with the whole set of compounds showing activity >22%, a (Q)SAR pharmacophore model for maskers of caffeine bitterness was calculated to explain the structural requirements. After docking of the pharmacophore into a structural model of the broadly tuned bitter receptor hTAS2R10 and docking of enterolactone and enterodiol as only very weakly related structures, it was possible to predict qualitatively their modulating activity. Enterodiol (25 mg L(-1)) reduced the bitterness of the 500 mg L(-1) caffeine solution by about 30%, whereas enterolactone showed no masking but a slight bitter-enhancing effect.     

How widespread is resistance to invermectin among gastrointestinal nematodes in sheep in The Netherlands?

In Autumn 2009, a faecal egg count reduction test (FERCT) was carried out on three sheep farms. Groups of 8-11 lambs were treated with ivermectin or moxidectin, with a 14-day interval between treatment and sampling. Ivermectin resistance was present on all three farms. Treatment with ivermectin resulted in a reduction in faecal egg numbers of 94.6%, 63%, and 59%. On two farms, 14 days after treatment pooled faecal samples yielded predominantly larvae of Hamonchus contortus (100% and 98%, respectively). On the third farm, H. contortus and (probably) Teladorsagia circumcincta were resistant to ivermectin (64% and 36% of the larvae, respectively). Treatment with moxidectin resulted in a 100% reduction in egg output in sheep on all three farms. More sensitive culture techniques failed to detect any larvae in samples taken from two farms, but a few Ostertagia-type larvae, probably of T. circumcincta, were detected in samples from the third farm. It can be concluded that gastrointestinal nematodes in sheep from these three farms were resistant to ivermectin, whereas resistance to moxidectin was not detected.     

Characterization of Potato spindle tuber viroid (PSTVd) incidence and new variants from ornamentals

We analyzed the spreading and persistence of PSTVd variants in several ornamentals in the territory of the Czech Republic. The pool of PSTVd variants detected in Solanum jasminoides, S. muricatum, Datura sp. and Brugmansia sp. was biolistically transferred to Matricaria chamomilla, Argyranthemum frutescens and Diascia sp., species which we found as sensitive hosts for PSTVd from ornamentals. The PSTVd pool showed sequence changes and increased variation after its transfer to potato, suggesting a wide adaptation potential of PSTVd in this crop. Potato exhibited genotype-dependent leaf and spindle tuber symptoms, when inoculated with the sap from S. jasminoides infected with the predominant and sequence-stable PSTVd-S1.