A method for the protection of spruce stands againstIps typographus by the use of barriers of pheromone traps in north-eastern Slovakia

A method and layout of various systems of barriers of pheromone traps is described. The rationale of the method is based on the stress of spruce and the chemical communication ofIps typographus. Various systems of pheromone trap barriers were used according to the required level of protection. The method was used in two areas affected by air pollution and bark beetle outbreak. The first area was in an unnatural spruce monoculture region while the second was in a National Park. The described method led to a significant reduction of bark beetle attacks on trees along forest edges and subsequently to the stopping of movement of the zone of attacked trees due to bark beetle damage. In the case of forest stands with no reduced canopy closure, the reduction of attacks led to a dramatic decline of bark beetle outbreak. On the other hand, this method was not able to reduce the level of bark beetle attack in the interior of forest stands with a decreased level of canopy closure. This method, as part of differentiated pest management measures in one forest district, was successful without any other protection measures in the condition of natural reserves in a spruce vegetation zone.     

Size‐related oxygen consumption and ammonia excretion of Eurasian perch (Perca fluviatilis L.) reared in a recirculating system

Oxygen consumption (OC) and ammonia excretion rates (AE) of perch were measured under commercial‐like conditions (temperature 23.3 °C) in both fed (F) and feed‐deprived groups (D). Measurements were taken in triplicate in six sized batches of perch ranging from 44.8 to 336.2 g. The mean daily OC was 288.3–180.6 mg O₂ kg^?1 h^?1 for group F fish ranging in size from 44.8 to 279.4 g body weight. The mean daily AE expressed as total ammonia nitrogen (TAN) was 13.8–5.2 mg TAN kg^?1 h^?1 in the same groups. Daily peaks of OC in group F perch were observed 6 h after the onset of feeding for each size group with relatively stable values up to the end of feeding. Peaks of daily AE in group F perch were observed 10 h after the onset of feeding in each size group, with a rapid decrease up to 16 h after onset. In group D, OC was 181.1–110.5 mg O₂ kg^?1 h^?1 in the weight range 57.9–336.2 g. The daily mean AE was 1.7–0.5 TAN kg^?1 h^?1 in this group. No dramatic peaks of OC and AE were observed in group D perch.     

Voracious invader or benign feline? A review of the environmental biology of European catfish Silurus glanis in its native and introduced ranges*

A popular species for food and sport, the European catfish (Silurus glanis) is well‐studied in its native range, but little studied in its introduced range. Silurus glanis is the largest‐bodied freshwater fish of Europe and is historically known to take a wide range of food items including human remains. As a result of its piscivorous diet, S. glanis is assumed to be an invasive fish species presenting a risk to native species and ecosystems. To assess the potential risks of S. glanis introductions, published and ‘grey’ literature on the species’ environmental biology (but not aquaculture) was extensively reviewed. Silurus glanis appears well adapted to, and sufficiently robust for, translocation and introduction outside its native range. A nest‐guarding species, S. glanis is long‐lived, rather sedentary and produces relatively fewer eggs per body mass than many fish species. It appears to establish relatively easily, although more so in warmer (i.e. Mediterranean) than in northern countries (e.g. Belgium, UK). Telemetry data suggest that dispersal is linked to flooding/spates and human translation of the species. Potential impacts in its introduced European range include disease transmission, hybridization (in Greece with native endemic Aristotle’s catfish [Silurus aristotelis]), predation on native species and possibly the modification of food web structure in some regions. However, S. glanis has also been reported (France, Spain, Turkmenistan) to prey intensively on other non‐native species and in its native Germany to be a poor biomanipulation tool for top‐down predation of zooplanktivorous fishes. As such, S. glanis is unlikely to exert trophic pressure on native fishes except in circumstances where other human impacts are already in force. In summary, virtually all aspects of the environmental biology of introduced S. glanis require further study to determine the potential risks of its introduction to novel environments.     

Evidence of scientific research on organic plant breeding: A bibliometric study

Use of varieties bred under organic conditions is essential in order to minimize the yield gap between organic and conventional agriculture. The aim of this study was to analyse research publications related to the topic ‘organic plant breeding’ from the Web of Science database using bibliometric science mapping and visualization tools. The number of analysed documents in the bibliographic dataset was 204 from the 53 sources. The overall trend in the organic plant breeding literature showed that the number of publications increased during the observed time-span. We found that in total, 65 countries and 337 institutions are active in the field of organic plant breeding with a high degree of international collaboration. The top five countries according to the number of publications were the United States, Italy, Germany, France, and Canada, while the most active institutions were Wageningen University, Iowa State University, University of Alberta, University of Copenhagen, and University of Hohenheim. All keywords from the organic plant breeding research in the agronomy category were separated into seven clusters for different research topics. Although there is evident progress viewed through the increased trend in the number of publications, organic plant breeding needs further expansion and development. This is especially through the implementation of novel plant breeding techniques and methods aiming to improve traits that are highly specific to organic conditions.     

Sperm quality in male <Emphasis Type="Italic">Barbus barbus</Emphasis> L. fed different diets during the spawning season

Sperm quality of Barbus barbus L. was compared among the three following dietary regimes: Group A, fed 100% commercial diet (Karpico™ containing 33% crude protein and 6% fat), Group B, fed 78% commercial diet and 22% frozen chironomid (Chironomus plumosus) larvae, and Group C, fed 56% commercial diet and 44% frozen chironomid larvae. Concentrations of polyunsaturated fatty acids (PUFAs) in Group A, B, and C were 39.1, 42.0, and 44.6, respectively, as a percentage of total fatty acids. Sperm morphology, volume, concentration and motility, total number of spermatozoa, and osmolality of the seminal plasma were compared during the spawning season. Dietary regime did not influence sperm volume, concentration, or total number of spermatozoa, osmolality of seminal plasma, or the percentage of motile sperm, but significantly affected sperm morphology (except for anterior and posterior parts of the midpiece) and sperm velocity (P < 0.05). Groups B and C showed similar sperm characteristics during the spawning season compared to Group A. Almost all parameters changed either among or within groups during the spawning season, suggesting differences in terms of the optimal time for sperm collection. The best time for sperm collection was March for Group A, but April for Groups B and C, when the osmolality of the seminal plasma measured 289 mOsmol kg⁻¹ and sperm motility was maximal. Spermatogenesis, hydration, and cell decomposition were confirmed as the three major parameters controlling sperm characteristics during the spawning season. The possible correlation between sperm morphology and motility requires further study.     

Changes in forest soil organic matter quality affected by windstorm and wildfire

Purpose

Windthrows and fires are major natural disturbances in forest ecosystems, which can affect organic matter in the surface and the mineral layer of forest soil. The main aim of this study was to evaluate the changes occurring in the structure and properties of humic acid (HA) in the lands where windthrows and wildfires occurred.

Materials and methods

In November 2004, the forest in the area of 12,000 ha in the Tatra National Park, Slovakia, was seriously damaged by northern wind gusts exceeding 200 km/h. In July 2005, a wildfire broke out in a 220 ha of wind-damaged area. The HAs have been isolated from four research plots: (a) the area where the fallen trees were removed (EXT); (b) an area after windstorm covered by wood from struck trees (NEX), left for spontaneous succession; (c) an area after extracted timber, damaged by the surface wildfire (FIR); and (d) a reference intact spruce forest area (REF). Changes in the chemical structure of the HAs isolated from the research plots were determined on the basis of elemental analysis and UV-Vis, EPR, IR, and ¹³C NMR spectroscopy.

Results and discussion

All used analytical methods showed a decrease in the humification degree of the humic acids extracted from the soils where the spruce forest has been affected by a wildfire and a windthrow. In the case of the control sample HA (REF), the calculated atomic H/C and O/C ratios and the degree of aromaticity (α) calculated from the ¹³C NMR spectra were higher, indicating higher aromaticity of HA from the REF area. The more complex and developed structure of REF HA was confirmed by the higher value of E^1%₆ and the lower E4/E6 ratio obtained using UV-Vis spectroscopy. Also, the higher g-parameters determined from the EPR spectra of the stable radicals present in HA confirmed the lower aromaticity on the plots that have been subjected to the calamities. The ¹³C NMR spectra and the elemental analysis show that the structure of the HA extracted from the NEX plot is the closest to the REF.

Conclusions

The results of the systematic research showed significant changes in the structure of HA taken from spruce forest soils that were subjected to windstorms and fires. An enrichment of the HAs in aliphatic carbon and so a lower humification degree of the organic matter in the areas calamity-affected were observed. The results clearly indicate that the HAs extracted from the disturbed plots of the spruce forest are not as stable as those extracted taken from the control plot.

     

The combined effects of multiple diseases and climatic conditions on thousand kernel weight losses in winter wheat

Thousand kernel weight (TKW) is a yield component associated with grain quality. It is reported in the literature that TKW is significantly influenced by varieties, agro-ecological conditions and disease indices, but the influence of their interactions on TKW loss has rarely been taken into consideration. The main objective of this study was to examine the combined effects of multiple diseases and climatic conditions on TKW losses in winter wheat. Leaf rust, powdery mildew, and Septoria tritici blotch were considered biotic predictor variables in regression models explaining TKW losses. Monthly averages of temperature, relative humidity and total rainfall in May and June in the 2006–2013 growing seasons were used as abiotic predictor variables. The results of this study indicated a significant low positive correlation between yield loss and TKW loss in the two varieties. TKW losses were less influenced by leaf rust, powdery mildew, and Septoria tritici blotch than yield losses. The significant influence of the interaction between variety and the environmental conditions on TKW loss was confirmed from the general linear model function. The results of this study indicated that factors influencing yield and yield component losses are part of the complex environment, and the relationship between them should be investigated with respect to their interactions.     

Rapid de-adhesion of northern pike <Emphasis Type="Italic">Esox lucius</Emphasis> eggs using sodium hypochlorite

The elimination of egg stickiness is required for effective artificial reproduction of northern pike, but until now, available methods have required at least 40 min. Sodium hypochlorite was tested under laboratory conditions, and exposure to aqueous concentrations of 0.025–0.05% for 40 s effectively eliminated stickiness without adverse effects. Fertilization and hatching rates in laboratory trials were similar to those observed in eggs treated with traditional methods using clay or milk for 40 or 60 min, respectively, as well as those without treatment. Testing using conventional hatchery incubation techniques did not reveal differences in fertilization rates, while the number of hatched larva was significantly higher in eggs treated with sodium hypochlorite vs. clay. Eggs treated with sodium hypochlorite retained transparency, which facilitated monitoring of embryo development.     

The impact of dry and wet cleaning on fabric electromagnetic field shield effect

The aim of this research is to investigate shield effect properties of the fabrics with inox yarns included in the construction, which are used for special professional garments and should protect from electromagnetic microwave irradiation. The investigation was done prior to and after the professional care procedures of dry and wet cleaning in ten cleaning cycles. Shield effect measurements were done on the face and on the back of the fabric, weftwise and warpwise, prior to and after the first, third, fifth, seventh and tenth cycles of dry and wet cleaning, at the frequencies from 0.9 to 2.4 GHz. The results obtained indicated that shield effect of the fabric tested was reduced after professional care procedures, especially so after 5 cycles. The investigations also revealed that shield effect could be considerably enhanced if the inox yarns were incorporated into the fabric in the direction of the warp.