Effect of humic substances in nutrient film technique on nutrient uptake

An experiment was conducted to find out how humic substances affected nutrient uptake of plants. The test plants, oregano, thyme, and basil, were grown in nutrient film technique at two pH levels (4.5 and 6.5), in two substrates (peat and perlite), and at three levels of humic substance that was a peat extract (control, low, and high concentration). Nutrient uptake of potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were determined by elemental contents in aerial parts of the plant and its weight. Humic substance had no effect on K, Ca, and Mg uptake but lowered the uptake of Fe, Mn, Zn, and Cu for the three test plants, more pronounced with perlite than peat and more at low pH than at high pH. The lowering of the uptake might be caused by complexation of Fe, Mn, Zn, and Cu by the humic substance and the lower availability of these metals in complexed form than as a cation or as EDTA‐chelate in the case of Fe. It is not clear why the effect of the humic substance on micro‐element uptake is larger at low than at high pH. The complexation is expected to be stronger at pH 6.5 than at pH 4.5. At low pH, the high concentration of humic substance caused a low fresh weight of the shoots, perhaps caused by a toxicity of the humic substance at low pH. This was less pronounced at high pH.     

Soil organic matter in water-stable aggregates under different soil management practices in a productive vineyard

In a productive vineyard, the influence of different soil management practices on carbon sequestration and its dynamic in water-stable aggregates of Rendzin Leptosol was studied. In 2006, an experiment of different management practices in a productive vineyard was established in the locality of Nitra-Dra?ovce, in the Nitra winegrowing area of Slovakia. The following treatments were established: (1) control (grass without fertilization); (2) T (tillage); (3) T + FM (tillage + farmyard manure); (4) G + NPK3 (grass + NPK 120–55–195 kg ha^?1); and (5) G + NPK1 (grass + NPK 80–35–135 kg ha^?1). The results showed that the lowest soil organic matter content (9.70 g kg^?1) in water-stable microaggregates was determined in G + NPK3, as well as in T. However, the highest soil organic matter content in the highest size fractions of water-stable macroaggregates (>5 mm) was observed in T + FM (19.7 g kg^?1). The highest value for carbon sequestration capacity in water-stable microaggregates was observed in the ploughed farmyard manure treatment. However, the control treatment showed the highest values for carbon sequestration capacity in water-stable macroaggregates, including agronomically favourable size fractions (0.5–3 mm). In all soil management practices under a productive vineyard the most intensive changes in the soil organic matter content were observed in the highest size fractions (>3 mm) of water-stable macroaggregates.     

Microbial responses to fluctuation of soil aeration status and redox conditions

 The response of the microbial community to changes in aeration status, from oxic to anoxic and from anoxic to oxic, was determined in arable soil incubated in a continuous flow incubation apparatus. Soil incubated in permanently oxic (air) and/or anoxic (O₂-free N₂) conditions was used as the control. Before experiments soil was preincubated for 6 days, then aeration status was changed and glucose added. Glucose concentration, extractable C, CO₂ production, microbial biomass, pH and redox potential were determined 0, 4, 8, 12, 16, 24, 36 and 48 h after change of aeration status. If oxic conditions were changed to anoxic, the amount of glucose consumed was reduced by about 60%, and CO₂ production was 10 times lower at the end of incubation compared to the control (permanently oxic conditions). Microbial biomass increased by 114% in glucose-amended soil but did not change in unamended soil. C immobilization prevailed over C mineralization. Redox potential decreased from +627 mV to –306 mV. If anoxic conditions were changed to oxic, consumption of glucose and CO₂ evolution significantly increased, compared to permanently anoxic conditions. Microbial biomass did not change in glucose-amended soil, but decreased by 78% in unamended soil. C mineralization was accelerated. Redox potential increased from +238 to +541 mV. The rate of glucose consumption was low in anoxic conditions if soil was incubated in pure N₂ but increased significantly when incubation was carried out in a CO₂/N₂ mixture. Received: 6 January 1999     

Distribution and Genotypic Characterization of Campylobacter jejuni Isolated from Poultry in Split and Dalmatia County,Croatia

Consumption of poultry contaminated with Campylobacter jejuni has been recognized worldwide as the leading cause of campylobacteriosis. Therefore, the aim of our study was to investigate the prevalence and genotype diversity of Campylobacter jejuni in poultry meat intended for consumption in Split and Dalmatia County, which is the second biggest County in Croatia. Furthermore, we also wanted to discover possibly stable clones of C. jejuni appearing in different samples and periods of time, which would indicate their ability to persist in or adapt to poultry. In the period from March 2008 until June 2010, 834 samples of poultry from various sources were examined using a surface swab technique. Isolation of C. jejuni was performed by Preston broth and Karmali agar. Identification of the isolates was carried out using biochemical tests. C. jejuni was found in 84 of 574 chicken samples (14.6%) and in nine of 260 samples of turkey (3.5%). Pulse‐field gel electrophoresis (PFGE) was used to analyse 61 obtained isolates using SmaI and KpnI. Of 22 different macrorestriction profiles (MRP) that were found, five were detected in poultry from both different locations and periods of time. Samples from 11 locations were found to be contaminated with more than two different genotypes of C. jejuni. Interestingly, the same MRP were found both in poultry declared to be of domestic origin and in the poultry imported from abroad. The prevalence of C. jejuni in poultry samples was in accordance with previously reported results. Genotypic analysis indicated that the population of C. jejuni in Split and Dalmatia County was diverse and that multiple strains of C. jejuni could be found in the same poultry samples. Furthermore, the same genotypes were identified from the samples obtained from different locations and periods of time, which could support the theory of a global existence of certain MRP that are able to persist in or adapt to poultry.     

Unambiguous identification of Ancylostoma caninum and Uncinaria stenocephala in Australian and New Zealand dogs from faecal samples

Hookworms (Ancylostomatidae) are well-known parasites in dogs due to their health impacts and zoonotic potential. While faecal analysis is the traditional method for detection, improvements in husbandry and deworming have decreased their prevalence in urban owned dogs. Drug resistance in Ancylostoma caninum is becoming a discussion point in small animal practices across the region. This study aimed to identify hookworm species present in Australian and New Zealand dogs using molecular techniques. The ITS-2 and isotype-1 β-tubulin assays were used to identify and quantify hookworm species. Results showed absence of coinfection in Australian samples from Greater Sydney region belonging either to A. caninum or Uncinaria stenocephala, while New Zealand samples were a mixture of A. caninum and U. stenocephala. The amplified isotype-1 β-tubulin sequences exhibited susceptibility to benzimidazole drugs. Rare mutations were identified in A. caninum and U. stenocephala sequences, representing a small percentage of reads. This study highlights the importance of molecular techniques in accurately identifying and quantifying hookworm species in dog populations.     

Die Fledermauswanze,Cimex dissimilis (Horvath) (Heteropt., Cimicidae), als Lästling in Paneeltafelhäusern

Bugs parasiting on boats burdensome in panel houses The troublesome occurrence ofCimex dissimilis (Horvath 1910) in tow new housing estates built of panel houses is recorded. The bugs parasiting on bats (Nyctalus noctula (Schreber)) seating in gaps on the southern and southwestern sides of the house crawled in the rooms bit men, soiled the bed linen, and were troublesome by their number.     

Modeling of heat and mass transfer during high temperature treatment of aspen

A three-dimensional and unsteady-state mathematical model, which accounts for simultaneous heat and mass transfer taking place during the high temperature treatment of wood, has been developed. It was validated by comparing the predictions with the experimental data. In the model, the coupled heat and mass transfer equations proposed by Luikov are solved, and the temperature and moisture content profiles within wood are predicted as a function of time for different heating rates. For the model validation, an experimental study was carried out with aspen under different operating conditions. The samples were heated to high temperatures using a thermogravimetric system. The weight loss and the temperature distribution within the sample were monitored and registered during the experiment. The model can use constant or variable thermo-physical properties. The temperature and moisture content of the wood predicted by the model using variable properties were compared with those predicted by the same model using constant properties as well as with the experimental data. The experimental and model results are in good agreement, and it was shown that the accuracy of the model depends on the accuracy of the properties. After the model validation was completed, a parametric study was carried out.     

Waldbauliche Analyse einer freien Hochdurchforstung in ungepflegten Buchenstangenhölzern

Zusammenfassung Das Material der Arbeit bilden die Beobachtungsergebnisse von fünf Dauerversuchsreihen (DVR), die in 30–40j?hrigen ungepflegten Buchen-Reinbest?nden in der Slowakei (CSSR) angelegt wurden. Die Arbeit umfa?t eine waldbauliche Analyse der ersten zwei in Form einer freien Hochdurchforstung erfolgten Eingriffe. Das Durchforstungsintervall betrug 4 Jahre. Die freie Hochdurchforstung, die an den DVR der Forschungsanstalt für Forstwirtschaft in Zvolen angewandt wurde, soll folgende Arten der Phytotechnik miteinander verbinden: die positive Oberstandauslese, die positive Unterstandauslese, die negative, die Sanit?r- und die relative Reifeauslese. Hauptgegenstand der waldbaulichen Pflege stellen die sog. Erwartungs- bzw. Zielb?ume dar. Für die Auswahl wurden in der Arbeit Qualit?ts-, Dimensions- und Abstandskriterien herangezogen. In den ursprünglich ungepflegten Buchenstangenh?lzern überwog, was das Volumen betrifft, in den gesunden Best?nden bei beiden Eingriffen die positive Oberstandauslese. Durch sie werden die Erwartungsb?ume gef?rdert. Sie kommt in den gesunden Best?nden an erster Stelle zur Geltung. In den stark erkrankten Best?nden tritt bei der Auszeichnung der Durchforstung dagegen die sanit?re Auslese in den Vordergrund. Erst dann folgt die positive Oberstandauslese. In ungepflegten Stangenh?lzern bietet bei der Hochdurchforstung die versp?tete S?uberung keine Vorteile gegenüber der positiven Oberstandauslese.

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Summary The author discusses the results of thinning experiments in pure beech stands in the CSSR. This article deals with an evaluation of experimental results in 5 series of permanent sample plots, which were established in 30 to 40 year-old stands. The thinning interval in these experiments was invariably 4 years. The method being a free selection thinning involved the following operations: a positive selection thinning in the upper storey, a positive selection thinning in the understorey, a negative sanitary thinning and the relative maturity selection. The most important objective in thinnings is to promote the growth of those trees which are selected to be retained until the end of the rotation. In untended beech stands priority was given to positive selection in the upper storey, whereas sanitary selection played an important part in diseased stands. This sanitary selection thinning is subsequently followed by a positive selection thinning in the upper storey.

     

Über die Wirkung von Bacillus thuringiensis in Kombination mit dem synthetischen Pyrethroid Ambusch auf Operophthera brumata,Tortrix viridana und die Insektenfauna eines Eichenbestandes

In order to increase the effect of the biopreparation Thuricide HP, we mixed it with pyrethroid Ambusch, a substance highly effective against insects possessing satisfactory parameters as regards toxic residua. Using aerial application, we tested Thuricide HP as a 0.5% suspension in a dose of 1 kg in 200 l water per one ha, the same dose of the preparation combined with a sublethal dose of Ambusch (8 ml/ha, i. e., 2 g of effective substance), and Ambusch in a dose of 120 ml/ha, i. e., 30 g of effective substance/1 ha. The mortality of larvae ofO. brumata andT. viridana attained 61% after the application of Thuricide HP, 83% after Thuricide HP combined with Ambusch, 96% after treatment with Ambusch. As indicated by our results, the biopreparation killed only larvae of Lepidoptera, while pyrethroid effected the entire spectrum of insect species colonizing the crowns of the treated stand. A combination of the biopreparation with a sublethal dose of pyrethroid was sufficiently effective against the pest, with a decreased effect on the remaining insect species.