Nitrogen transformations in copper-contaminated soils and effects of lime and compost application on soil resiliency

 A neutral and an acidic soil were treated with different doses (0–3,000 mg Cu kg^–1 soil as CuSO₄) of copper. The percentages of inhibition of nitrification in both soils varied from 5 to 97%, but for the N mineralization these percentages varied from 8 to 65%. The toxic effect of Cu for basal nitrification and N mineralization was assessed as critical. Nitrification was more sensitive than ammonification to copper toxicity. It appears that an ecological dose of inhibition for nitrification and N mineralization higher than 10% is suitable as an indicator for Cu contamination. Soil resiliency assessed by N mineralization in the lime treatments varied from 11 to 154% in the sandy soil and from 70 to 168% in the sandy loam soil. A combined application of lime and compost significantly increased soil resiliency. The percentage increase varied from 904 to 1,390% in the sandy soil and from 767 to 2,230% in the sandy loam soil. It appears that compost was a powerful agent for recovering the soil fertility of Cu-contaminated soils as assessed by N transformation. The acidic sandy soil showed a lower capacity for recovery after Cu toxicity stress. Received: 27 February 1999     

Microbial Activity of Cu Contaminated Soils and Effect of Lime and Compost on Soil Resiliency

In vineyards, the long-term use of copper fungicides has increased soil Cu concentrations that can adversely affect the number and activities of soil microorganisms. To better understand this phenomenon and to ameliorate such harmful effects, an incubation experiment was carried out with a sandy loam and a sandy soil to which increasing rates of CuSO₄ were added. By this treatment, the basal soil respiration (7-55%) and decomposition of added vine branches (46-86%) was inhibited. At the application rate of 500 mg Cu kg^?1, soil microbial biomass-C was inhibited (7-66%) in the sandy soil and stimulated (2-10%) in the sandy loam soil. The specific respiration rate was a reliable indicator for Cu stress, and it increased with time and higher Cu concentrations before lime and compost applications. Total number of bacteria and streptomycetes were also strongly inhibited. Fungal population was significantly more tolerant to copper toxicity than the bacteria. A stimulation of fungal population at a dose of 500 mg Cu kg^?1 in both soils was observed. A criterion such as “stimulation” lasting for more than 60 days can also be used as indication of Cu contamination of soils. The order of inhibition (on day 125) at a dose of 500 mg Cu kg^?1 soil was as follows: A. sandy loam soil (pH> 7.0) — fungi < biomass-C < basal soil respiration < bacteria < streptomycetes; B. sandy soil (pH< 6.0) — fungi < basal soil respiration < biomass-C < bacteria < streptomycetes. The application of lime increased soil recovering ability at a moderate rate (for CO₂ production – 22-70% and for biomass-C- 39-156%), but the combination of lime and compost significantly increased soil resiliency (for CO₂ production- 16-518% and for biomass-C- 103-693%). The soil resiliency assessed by number of bacteria in compost treatments was 30-120% in sandy loam soil and 92-700% in the sandy soil. Compost and lime application increased the number of streptomycetes from 52 to 500% in sandy loam soil and from 100 to 700% in sandy loam soil. Fungal population was less increased in sandy soil as compared to sandy loam soil. The ecological dose higher than 5% inhibition of microbial processes and microorganisms appears to be suitable to assess Cu contamination of soils. CO₂ production, biomass-C and specific respiration rate were less sensitive indicators as compared to streptomycetes and bacteria. It appears that compost application effectively promoted the recovery of soil microbial activity and soil fertility of Cu contaminated soils.     

First report of Phytophthora pseudosyringae recovered from aquatic ecosystems in Bulgaria

Two Phytophthora pseudosyringae isolates were recovered from aquatic ecosystems in Bulgaria during a two‐year investigation of Phytophthora distribution in water sources in the country. Isolate RVit2016/6d was derived from Boyana Lake at the Vitosha Mountain, whereas isolate RTr2016/32d was obtained from Erma River at the Ruy Mountain. Both isolates belong to P. pseudosyringae species according to their morphological and physiological characteristics, as well as to the DNA sequence analysis of the internal transcribed spacer (ITS) region. The pathogenicity of the isolates to wild cranberry plants (Vaccinium vitis‐idea) was studied by detached leaves experiments and in planta. Both P. pseudosyringae isolates were able to cause leaf necrosis and death of plants within 3 months. The ability of the pathogens to infect cranberry leaves at different temperatures was also investigated. The significance of P. pseudosyringae species and its potential threat for forest ecosystems is discussed. To our knowledge, this is the first report of P. pseudosyringae isolation in Bulgaria.     

The gene flow and mode of reproduction of Dothistroma septosporum in the Czech Republic

Since 1911, dothistroma needle blight, caused by Dothistroma septosporum, has been recorded in most European countries. In the Czech Republic, the fungus has become an important disease of pines since 2000, especially Austrian pines in plantations of Christmas and ornamental trees. The aim of this study was to analyse the population structure, gene flow and mode of reproduction of this pathogen. Microsatellite and mating‐type markers were analysed in a Dothistroma population in the southeastern part of the country using reference isolates from other European countries. The haplotypic diversity was high, with 87 unique and 13 shared haplotypes (probable clones) identified in 121 samples. Based on structure analysis, the isolates were divided into two populations, with an uneven distribution over the sampling sites. The grouping of the sites to the populations did not follow a geographical pattern because certain isolates that were sympatrically co‐occurring at the same site were placed in different populations. Tests for random mating (the index of association and a parsimony tree‐length permutation test) showed a significant clonal mode of reproduction in most cases, but the intrapopulation haplotypic diversity is unexpectedly high. Although a teleomorphic stage of D. septosporum has not been previously observed in the Czech Republic, the high intrapopulation haplotypic diversity can be explained by infrequent sexual reproduction consistent with the occurrence of both mating types.     

Implementation of RNAi-based arthropod pest control: environmental risks,potential for resistance and regulatory considerations

Journal of Pest Science - Just over 20 years since the RNA interference (RNAi) mechanism was unraveled in the nematode Caenorhabditis elegans, the first RNAi-based pest control applications are...     

Correction to: RNAi,what is its position in crop protection?

Journal of Pest Science - A correction to this paper has been published: https://doi.org/10.1007/s10340-021-01393-0     

Electrophysiological characteristic of the ventromedial hypothalamic nucleus and lateral hypothalamic area in normally fed and 24 hour food deprived conscious sheep

We registered telemetrically the spontaneous electrical activity of the hypothalamic ventromedial nucleus (VMH) and the lateral hypothalamic area (LH) in conscious adult sheep-male, with implanted electrodes,-in a state of normal feeding or after 24 hour food deprivation. The frequency of electrical activity, the amplitude of electrical activity and the frequency by Fourier analysis were evaluated. The frequency of electrical activity was found to be approximately the same in the VMH and LH with mean values +/- S.E.M. 11.5 +/- 0.5 Hz in feed sheep. The amplitude of electrical activity in the VMH was higher compared with the LH, with mean absolute values +/- S.E.M. 41.5 +/- 2.7 microV in the VMH and 35.5 +/- 3.2 microV in the LH. The Fourier analysis showed that from the total amount of harmonic frequencies-the first one i.e. the basic frequency represented 48-56%, the rest are higher frequencies. In sheep after 24 hour food deprivation the frequency of electrical activity decreased on 9.4-9.6 Hz in average in both regions under study and the absolute values of the amplitude of electrical activity increased. The mean absolute value +/- S.E.M. was 115 +/- 5.2 microV in the VMH and 101.2 +/- 3.0 microV in the LH. Along with theses changes we found by Fourier analysis that in the total amount of harmonic frequencies the basic frequency decreased by 6% due to the greater amount of higher harmonic frequencies.     

Alien freshwater fish species in the Balkans—Vectors and pathways of introduction

Fish introductions, particularly in areas of high biological diversity and endemism, represent a major threat for biodiversity. In the Balkan Peninsula, 60 fish species have been introduced to date, of which 36 have become naturalized in inland waters. Since the Balkans are one of the world's 35 biodiversity hot spots, this large presence of alien fish species poses a serious threat for the stability of freshwater ecosystems and the survival of the native ichthyofauna and of aquatic biodiversity in general. The motivation for the introductions, and the historical timeline, varies among the Balkan states. Despite recent attempts to implement and align legislation aimed at preventing the introduction of potentially invasive species, and the implementation of rigorous controls of introductions and increased protection of open waters, the majority of current introductions remain intentional, primarily via aquaculture. This review article provides a historical overview of freshwater fish introductions, the motivation behind them and the current distribution of alien freshwater fishes in the Balkans. The ecological implications and future perspectives concerning alien fish species in the region are also discussed.     

Preparation and characterization of fibers of waste and fresh polyethylene terephtalate and mixtures of them

Textile fibers were obtained from secondary polyethylene terephtalate (PET) and its mixtures with primary PET at initial orientation of 18000–33000 %, rate of additional orientation drawing 3.5–6.5 times and temperature of thermal fixation 363–413 K. The fibers’ tensile strength was found to decrease and elongation at break to increase with the decrease of their linear density under the conditions of fibers formation. For the fibers based on polymer mixtures, the presence of oxidized fragments in the secondary PET limited the compatibility of the two polymers which resulted in deteriorated tensile properties. The linear density (4–16 dtex), tensile strength (30–50 cN/tex) and elongation at break (20–60 %) of the PET fibers obtained were close to these for the industrially produced polymer fibers. The values of the average diameter of the fibers formed and oriented under laboratory conditions allows classifying them between the fine and the coarse textile fibers which makes them suitable for the textile industry.