Head infection and accumulation of Fusarium toxins in kernels of 12 barley genotypes inoculated with Fusarium graminearum isolates of two chemotypes

Twelve barley genotypes were inoculated with two F. graminearum isolates of different chemotype I₁ #148 (producing nivalenol/deoxynivalenol) and I₂ #108 (deoxynivalenol/acetyldeoxynivalenol). For both I₁ and I₂ isolates, respectively, reductions (%) in number of kernels head^-1 10.6 and 14.3; yield 39.6 and 35.7; weight of 1000 kernels 36.9 and 23.2 were observed in inoculated plants from control values. Chemical analysis revealed the presence (average concentration mg kg^-1) of deoxynivalenol (1.3) and nivalenol (3.2) in kernels of all genotypes inoculated with the I₁ isolate, and zearalenone (0.2) in three samples. After inoculation with the I₂ isolate, deoxynivalenol (37.8) and zearalenone (0.4) were found in kernels of all genotypes, while 3-acetyldeoxynivalenol and 15-acetyldeoxynivalenol, respectively, were determined in five and four samples only. No significant correlation between examined characteristics was found for either the I₁ or I₂ isolate. The results obtained contribute information on the accumulation of toxins in cereal grain inoculated with F. graminearum isolates of different chemotypes.     

The Oxidants and Antioxidant Enzymes in Tomato Leaves Treated With O-Hydroxyethylorutin and Infected with Botrytis cinerea

Application of o-hydroxyethylorutin restricted the development of Botrytis cinerea in tomato leaves. Superoxide anion and hydrogen peroxide generation rates and changes in superoxide dismutase, peroxidase and catalase activities were studied in uninfected tomato plants, in plants infected with B. cinerea, and in plants treated with o-hydroxyethylorutin and infected with pathogen. About two times higher hydrogen peroxide concentration were found in plants treated with o-hydroxyethylorutin and infected with the pathogen at the early infection stages compared with untreated infected plants. In vitro tests showed that germination of B. cinerea conidia was significantly inhibited by H₂O₂. Higher H₂O₂ concentrations were needed to inhibit mycelial growth. The results indicate that o-hydroxyethylorutin triggers hydrogen peroxide production in tomato plants and suggest that enhanced levels of H₂O₂ are involved in restricted B. cinerea infection development.     

Results of the systematic survey and control of Plum pox potyvirus in Slovenia

Sharka, caused by Plum pox potyvirus (PPV), was first observed in Slovenia in 1987. In the following years, the presence of PPV was confirmed by DAS-ELISA in samples originating from orchards, individual trees and propagation material of stone fruits. In 1998, a systematic survey was initiated to prevent and control the spread of sharka and to establish pest-free production sites. In the first 3 years of the systematic survey, the presence of PPV was also monitored outside production sites for propagating material and their buffer zones, in order to establish the current incidence of sharka in Slovenia. The results showed an overall presence of PPV infection in Slovenia. Since 2000, the survey has focused mainly on nurseries, mother trees and stool-beds. In spite of strict official supervision and eradication measures, the incidence of sharka in propagating material production sites increased until 2002. A significant decrease in the number of PPV-infected mother trees, stool-beds, nurseries and buffer zones was finally obtained in 2002, as a consequence of the vast effort dedicated to containment of sharka in Slovenia.     

Polymorphism of caprine milk alphas1-casein in relation to performance of four Polish goat breeds

Polymorphism of goat milk alphas1-casein was determined and potential relations between genetic variants of this protein fraction and goat performance were evaluated. The investigations were performed on 598 goats assigned to of 4 breed groups (White improved 254 units, Coloured improved--124, White non-improved--146 and Coloured non-improved--74). For each goat, alphas1-casein polymorphism was determined in polyacrylamide gel by the PAGE-SDS method and percentage of milk alphas1-casein and gene frequency established. There was evaluated goat performance at successive lactations. In the goat population investigated, AA, AB, BB, AE, BE and EE alphas1-casein genotypes were identified. In all four breeds, alphas1-casein genotype EE clearly predominated (27.2-39.2%), recognized as "medium" and its share was higher in the groups of non-improved goats. It was conditioned by high frequency of gene E alphas1-casein (0.419-0.622). Generally, EE genotype percentage was higher in the non-improved goat groups. The improved goats, though, obtained higher productivity in each of the lactation studied. Analysis of relationships between alphas1-casein genetic variants and goats performance confirmed a significant influence on milk, protein and fat yields only in the Coloured improved goat group. There was revealed a more general tendency indicating a significant impact of "strong" alphas1-casein genotypes on a concentration of basic milk components, i.e. fat and protein, especially casein. In a group of goats producing milk of the highest casein content (over 2.4%) and protein (over 3.0%), the animals showing "strong" alphas1-casein variants dominated (85 and 70 %).     

Impact of thermal modification on color and chemical changes of spruce and oak wood

Thermal modification of wood is an environment-friendly alternative method for improving several properties of wood without the use of chemicals. This paper deals with the examination of color and chemical changes in spruce (Picea abies L.) and oak wood (Quercus robur F.) that occur due to thermal treatment. The thermal modification was performed at 160, 180, and 210 °C according to thermowood process. The color changes were measured by the spectrophotometer and described in the L*a*b* color system. Chemical changes were examined by wet chemistry methods, infrared spectroscopy and liquid chromatography. During the experiment, oak samples showed smaller color changes than spruce samples at all temperature values. During thermal modification, the content of cellulose, lignin, and extractives increases; however, the hemicellulose content drops by 58.85% (oak) and by 37.40% (spruce). In addition to deacetylation, new carbonyl and carboxyl groups are formed as a result of oxidation. Bonds in lignin (mainly β-O-4) and methoxyl groups are cleaved, and lignin is condensed at higher temperatures.     

What Characteristics of Soil Fertility Can Improve in Mixed Stands of Scots Pine and European Beech Compared with Monospecific Stands?

According to the current trends in forest management, endeavors are made to adjust the species composition to the site conditions and to increase the biodiversity. Changes in the species composition of forest stands lead to modifications of soil properties and nutrients cycle. The objective of the study was to evaluate the effect of monocultures (beech and pine) and mixed-species stands (pine-beech) on soil properties, particularly accumulation of soil organic carbon. We aim to demonstrate how different vegetation types influence soil properties in surface horizons of soil. The study sites are located in Germany and Poland under different tree stands Pinus sylvestris L., Fagus sylvatica L., and mixed-species stand. Contents of organic carbon and nitrogen, pH, and soil texture were analyzed. The studies conducted confirmed the positive effect of beech and mixed-species stands on acidification of surface soil horizons. We ordered the stands tested according to acidification effect on soils: pine stand > mixed stand > beech stand, which is consistent with previous studies. The most beneficial impact on the accumulation of organic carbon was observed in mixed-species stands in which beech and pine were found. Lower carbon-to-nitrogen (C/N) ratios confirm the high rate of organic matter decomposition and lower C/N ratio was reported in soil under beech stand in comparison to pine stands.     

The Impact of Diesel Oil Pollution on the Hydrophobicity and CO<Subscript>2</Subscript> Efflux of Forest Soils

The contamination of soil with petroleum products is a major environmental problem. Petroleum products are common soil contaminants as a result of human activities, and they are causing substantial changes in the biological (particularly microbiological) processes, chemical composition, structure and physical properties of soil. The main objective of this study was to assess the impact of soil moisture on CO₂ efflux from diesel-contaminated albic podzol soils. Two contamination treatments (3000 and 9000 mg of diesel oil per kg of soil) were prepared for four horizons from two forest study sites with different initial levels of soil water repellency. CO₂ emissions were measured using a portable infrared gas analyser (LCpro+, ADC BioScientific, UK) while the soil samples were drying under laboratory conditions (from saturation to air-dry). The assessment of soil water repellency was performed using the water drop penetration time test. An analysis of variance (ANVOA) was conducted for the CO₂ efflux data. The obtained results show that CO₂ efflux from diesel-contaminated soils is higher than efflux from uncontaminated soils. The initially water-repellent soils were found to have a bigger CO₂ efflux. The non-linear relationship between soil moisture content and CO₂ efflux only existed for the upper soil horizons, while for deeper soil horizons, the efflux is practically independent of soil moisture content. The contamination of soil by diesel leads to increased soil water repellency.