No reason for keeping 0+ perch (Perca fluviatilis L.) with the prey fish     

Martin Bláha  Irena Šetlíkova  Jiří Musil  Tomáš Policar 《Aquaculture International》2013,21(4):883-896

Growth and survival of 0+ perch were studied in 4 ponds with the topmouth gudgeon (Pseudorasbora parva) and without it. In the end of April, all ponds were stocked by free-swimming perch larvae (120,000 ind ha^?1). In June, topmouth gudgeon was introduced as forage fish (40 kg ha^?1) into two of the experimental ponds. Topmouth gudgeon significantly influenced neither the total abundance of zooplankton nor the abundance of its groups (Rotifera, Cladocera, Copepoda). The most important food item for perch (TL > 29 mm) was macroinvertebrates (especially Chironomidae). In the ponds with topmouth gudgeon, copepods and cladocerans were more important than in ponds without it. Specific growth rate of perch was 0.01 mm day^?1 in all ponds. Final mean total length (TL ± SD) of perch was 73 ± 13 and 70 ± 6 mm in the ponds with topmouth gudgeon and without it, respectively. Only 1 % of the perch reached higher TL than that recorded in the ponds without the topmouth gudgeon. Survival rate of perch varied from 12 to 36 % depending on ponds. Piscivory was recorded in all ponds from the age of 57 days (post-stocking); however, perch siblings were preferred to topmouth gudgeon. The highest asymptotic growth (L∞ = 88 mm) was calculated in the pond stocked with topmouth gudgeon. This corresponded with the highest cannibalism and lowest survival rate (12 %). Perch growth rate increased till 42–53 days of perch age and then started to decrease. There was no significant influence of potential prey fish (topmouth gudgeon) on the growth of 0+ perch; however, two size cohorts were found in the ponds with the topmouth gudgeon. Presence or absence of littoral macrophytes seems to be more substantial for rearing perch in ponds than stocking with the prey fish.  相似文献   

Sequence comparison and transmission of <Emphasis Type="Italic">Blackcurrant reversion virus</Emphasis> isolates in black,red and white currants with black currant reversion disease and full blossom disease symptoms     

J. Přibylová  J. Špak  K. Petrzik  D. Kubelková  V. Špaková 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(1):67-75

We collected samples from black, red and white currants showing symptoms of blackcurrant reversion disease (BRD) and full blossom disease (FBD), cultivated in the Czech Republic. Blackcurrant reversion virus (BRV) was detected in all symptomatic plants. After amplification, a substantial part of the 3′ non-translated region (3′-NTR) of RNA2 of 15 new isolates of BRV was sequenced and compared with sequences available in the literature and GenBank. We did not find significant sequence diversity among isolates associated with either FBD or BRD. BRV was graft-transmitted from FBD infected red currant to black currant where symptoms of BRD were observed. Further sequence analysis of BRV isolates resulted in a phylogenetic tree with four branches, each consisting of six to nine isolates. No correlation with geographic origin was visible on the tree as isolates from various countries occurred in all four branches. We also found no correlation between the host and the topology of the tree: most of black currant isolates occurred in branches 3 and 4, but also occurred in branches 1 and 2. Only one white currant and one red currant isolate occurred in branches 3 and 4, respectively. The sequence identity of the Czech isolates in this region ranged from 91.9 to 99.8%. The 17 plant species growing within and in the close vicinity of the BRD-infested plantation were tested negative for BRV by RT-PCR as natural hosts of BRV. BRV was successfully transmitted by mechanical inoculation from black currant to Nicotiana occidentalis and N. tabacum cv. Xanthi, the latter being a new host for BRV. The infection was confirmed by PCR and sequencing.  相似文献   

Glutelin protein fraction as a tool for clear identification of Amaranth accessions     

Mária Džunková  Dagmar Janovská  Petra Hlásná Čepková  Anna Prohasková  Michal Kolář 《Journal of Cereal Science》2011

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Photoperiod and Soil Munition Constituent Effects on Phytoaccumulation and Rhizosphere Interactions in Boreal Vegetation     

Ryan R. Busby  Robyn A. Barbato  Carina M. Jung  Kate A. Morozova  Anthony J. Bednar  Andrew L. Bray  Jenifer M. Milam  Jared C. Smith  Karl J. Indest 《Water, air, and soil pollution》2018,229(12):380

Permafrost thaw is expected to alter biogeochemistry and hydrology, potentially increasing the mobility of soil constituents. Northern latitude boreal forests where permafrost thaw is occurring also experience extreme changes in day length during the growing season. As the effects of photoperiod on plant uptake of soil constituents or interactions with the rhizosphere are unknown, our objective was to determine these interactions with three plant species from different functional groups. A tree, forb, and grass common to military training ranges in this region were grown in soil spiked with or without lead, antimony, or 2,4-dinitrotoluene and grown under 16, 20, or 24 h of light. Plant biomass, soil constituent uptake, and rhizosphere bacterial communities were compared between treatments. Photoperiod had no effect on plant uptake of any soil constituent or on rhizosphere community, indicating that plants and their associated microbial communities adapted to this environment are resilient to extremes in photoperiod. Lead uptake was not significant in any plant species and had no effect on the rhizosphere. Antimony increased the percentage composition of Saprospirales in the rhizospheres of two of the three plants, indicating an interaction between this bacterial order and antimony. Antimony uptake by white spruce (Picea glauca) was considerable, with a mean concentration of 1731 mg kg^?1 in roots, while mean shoot concentration was only 155 mg kg^?1, indicating its potential to phytostabilize this heavy metal. Although antimony had the strongest impact on the rhizosphere bacterial community, it was also readily accumulated by the grass and tree.  相似文献   

The effect of postsurgical pain on attentional processing in horses     

Louise Dodds  Laura Knight  Kate Allen  Joanna Murrell 《Veterinary anaesthesia and analgesia》2017,44(4):933-942

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Effects of drought and rewatering on growth and transpiration in European beech seedlings late in the growing season     

Martina Hájíčková  Roman Plichta  Daniel Volařík  Roman Gebauer 《New Forests》2017,48(6):773-784

Drought stress is one of the most important environmental factors affecting plant growth and survival. To date, most studies aim at understanding of post-stress physiological and anatomical adaptation to drought stress; however only few studies focus on plant recovery. In the present study, transpiration, shoot water potential, and anatomical and morphological measurements were performed on 4-year-old European beech seedlings with fully developed leaves. The seedlings were exposed to three levels of soil water potential (well-watered, moderate drought stress and severe drought stress) and followed by rewatering under greenhouse conditions. Reduced transpiration rates were observed in the stressed seedlings as a response to drought stress, whereas anatomical and morphological variables remained unchanged. Three days after rewatering, transpiration rates in both moderately and severely stressed seedlings recovered to the levels of those of well-watered seedlings. Drought stress promoted leaf budding, resulting in higher shoot dry mass of stressed seedlings. Our findings indicate that anatomical and morphological adaptations of European beech seedlings to drought stress are visibly limited during late-season growth stages. These results will help us to further understand factors involved in drought adaptation potential of European beech seedlings faced with expected climate-related environmental changes. To complete our findings, further experiments on plant recovery from drought stress should be focused on different periods of growing season.  相似文献   

Dyeing and fastness properties of natural dyes extracted from eucalyptus leaves using padding techniques   总被引：1，自引：0，他引：1  

Rattanaphol Mongkholrattanasit  Jiří Kryštůfek  Jakub Wiener 《Fibers and Polymers》2010,11(3):346-350

A natural dye extracted from eucalyptus leaves was applied to a silk and wool fabric by the use of two padding techniques, namely the pad-batch and pad-dry techniques under different conditions. Silk and wool fabrics dyed in a solution composed of eucalyptus extract from leaves showed a shade of pale yellow to brown. The exception was when the fabric was dyed with ferrous mordant, resulting in a shade of dark grayish-brown. The fastness properties ranged from good to excellent, while light fastness was fair to good.  相似文献   

Reduction of herbivore density as a tool for reduction of herbivore browsing on palatable tree species     

Jiří Kamler  Miloslav Homolka  Miroslava Barančeková  Jarmila Krojerová-Prokešová 《European Journal of Forest Research》2010,129(2):155-162

Browsing of overabundant free-living herbivores often limits the natural as well as artificial regeneration of forest in Central-European Mountains. The aim of the study was to assess the efficiency of the extensive reductions of herbivore populations for protection of forest regeneration in preferred areas. We analysed the relationship between the intensity of shoot browsing and relative density of herbivores in viewpoint of natural regeneration of secondary mountain spruce stands with low proportion of broadleaved trees in Králicky Sněžník Reserve (Czech Republic). The distribution of seasonally migrating herbivores was established by counting faecal pellet groups (standing crop method) in growing season. The intensity of browsing of spruce, beech and rowan was assessed using the proportion of browsed shoots on individual tree sapling. Density of red deer was re-counted from the number of pellet groups and it was 15–56 individual/km². The intensity of spruce browsing was low in the whole area in all seasons. In general, the intensity of rowan and beech shoot browsing was high in the whole area. There were no correlations between deer density and browsing intensity of rowan (browsing was severe in all plots). We conclude that the natural regeneration of attractive trees and shrubs is nearly impossible in habitats where proportion of these food items is too small, even when the density of herbivores is low. Reduction of herbivores density is useful for protecting spruce and other tree species with low preference by herbivores. Forest managers should take into account the high palatability of deciduous tree species and distribution of herbivores on localities. Preference of localities is often based on grasses in the food supply. Regeneration of highly palatable tree species requires both low density of herbivores and sufficient protection of saplings.  相似文献   

Leishmaniasis in a dog native to Colorado     

Freeman KS  Miller MD  Breitschwerdt EB  Lappin MR 《Journal of the American Veterinary Medical Association》2010,237(11):1288-1291

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The role of cytokinins in clubroot disease     

Robert Malinowski  Ondřej Novák  M. Hossein Borhan  Lukáš Spíchal  Miroslav Strnad  Stephen A. Rolfe 《European journal of plant pathology / European Foundation for Plant Pathology》2016,145(3):543-557

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