Yersinia ruckeri—A threat not only to rainbow trout

Yersinia ruckeri (Y. ruckeri) can cause mortalities that are contributing to substantial economic losses in the rainbow trout (Oncorhynchus mykiss) aquaculture sector. Because of its most characteristic clinical signs, the disease in rainbow trout caused by this pathogen is called enteric redmouth disease. Although it is considered to affect mainly salmonids, there are reports in the available literature of isolating this bacterium from other fish species, both clinically healthy and diseased. The aim of this study was to analyse the available data concerning yersiniosis in non‐salmonid fish. The analysed data indicate that Y. ruckeri is a threat not only to rainbow trout. Some of the affected species have high commercial importance and mortalities may contribute to high economic losses. The disease symptoms may not be specific and can be different from those characteristic for enteric redmouth in trout, which may lead to misdiagnosis. Collected information indicates that infection with Y. ruckeri should be taken into account in the diagnostic procedures not only in salmonids.     

Loss in macronutrient pools in bilberry and lingonberry in mesic Scots pine forests after Northern red oak introduction

Forest transformation from coniferous monocultures to mixed stands is being promoted worldwide, including the introduction of fast-growing broadleaved tree species within native stands. Here, we studied how enrichment of temperate European Scots pine (Pinus sylvestris) forest by North-American northern red oak Quercus rubra impacted macronutrient concentrations in two long-lived and dominant components of the forest understory: bilberry Vaccinium myrtillus and lingonberry V. vitis-idaea. Study sites were located in forest complexes (central Poland) which occupy continuously reforested lands (hereafter ancient forests) as well as post-agricultural lands (recent forests), all suitable for mesic pine forests. Samples of bilberry and lingonberry leaves, stems, and fruits were collected in pine stands and in adjacent Scots pine-red oak stands, in both ancient and recent forests. Concentrations of macronutrients (C, N, P, K, Ca, S, and Mg) in aboveground biomass components were analysed using standardized chemical procedures. The study revealed intra- and interspecific (bilberry vs. lingonberry) differences in concentrations of all nutrients in leaves, stems, and fruits, except for invariable C concentrations. Macronutrient accumulations in plants were decreased by land-use discontinuity and favoured by enrichment of tree stands by Q. rubra. The estimated macronutrient pools were much higher for V. myrtillus than V. vitis-idaea in all forest types studied. They were lower in forests enriched with Q. rubra, both ancient (up to 25.5% for bilberry and 99.9% for lingonberry) and recent (46.9% and 99.9%, respectively), as well as in recent pine forest (46.6% and 81.1%, respectively) than in ancient pine forest. Higher K and S pools (39.3% and 6.5%, respectively) noted for bilberry in an ancient forest with Q. rubra were exceptions. Despite more effective accumulations of elements at the species level, macronutrient pools of Vaccinium myrtillus and V. vitis-idaea decreased significantly in the presence of introduced Q. rubra due to negative impacts of this broadleaved tree on bilberry and lingonberry cover and biomass. Therefore, the limitation of alien Q. rubra planting in sites of mesic pine forest with the abundant occurrence of V. myrtillus and/or V. vitis-idaea is recommended.

Graphic abstract

     

Oak (Quercus robur L.) regeneration in early successional woodlands grazed by wild ungulates in the absence of livestock

Wooded pastures grazed by livestock are believed to be landscapes that provide favourable conditions for spontaneous regeneration of oaks, including Quercus robur. A key mechanism for oak regeneration in these systems is ‘associational resistance’, spatial association with unpalatable plants which offer protection against herbivory. There is little knowledge on how oak regenerates without livestock grazing and in the presence of only wild large herbivores. We studied this in an area (114 ha) abandoned from agricultural use and in the early 1980s incorporated into the Bia?owie?a National Park, Poland. Its ungulate community consists of native red deer, European bison, roe deer, moose and wild boar. Secondary succession has led to the development of a mosaic habitat including tree and tall shrub groves (29% of the area), open meadow communities (60%), and edge, transitory zone between groves and meadows (11%). Our systematic inventory assigned oaks to height classes (0-0.2, 0.2-0.5, 0.5-1.3, 1.3-2.5, 2.5-5.0, >5.0 m), dichotomous shape characteristic (regular vs. “bonsai” sapling), as well as a habitat definition, in particular the characteristics of woody vegetation in the immediate surroundings of oaks. A selection of 17 oaks was subject to coring for the comparison of growth dynamics. Oak density was highest inside groves, with 504 oaks ha⁻¹, and in the edge zone (493 oaks ha⁻¹) and lowest in meadows (47 oaks ha⁻¹). Most of the 0-5-m oaks (62%) grew without another woody plant species within 1 m radius. The remaining oaks (38%) were associated mainly with Rubus idaeus and saplings of Carpinus betulus and Populus tremula - all highly ungulate-preferred species. The age (0.5 m above ground) of cored oaks in grove and edge habitats varied from 11 to 37 years, indicating continuous recruitment since agricultural abandonment. The initial growth dynamics of the more mature oaks did not differ from that of present “bonsais,” supporting the idea that browsing is not an unconditional impediment and that “bonsai” can be a temporary stage of successful oak development. In contrast to other studies, we found that associational resistance from unpalatable plants is not necessary to secure successful oak regeneration in woodlands subject to browsing by wild ungulates. This might have been possible because of the abundance of highly attractive vegetation making oak relatively unpreferred by ungulates. We suggest that the observed secondary succession provides a contemporary analogy of historic processes that resulted in the establishment of broadleaf forests with a substantial proportion of oak.     

Androgenic capability among genotypes of winter and spring barley

Variable efficiency of androgenesis remains a serious problem in many species of cereals. It is still unclear what makes certain genotypes more amenable to androgenesis than others. This study was undertaken to quantify the previously suspected advantage of winter barley genotypes over spring ones with regard to regeneration efficiency in anther culture. The material consisted of 40 barley hybrids originating from Polish breeding companies. The number of androgenic structures per 100 anthers did not differ significantly between analysed groups (119 vs. 152 non‐significant), but the average regeneration of green plants per 100 anthers was five times higher in winter genotypes (6.4 vs. 1.3). The incidence of albinism was lower for the winter than for the spring materials (70% vs. 90%), while the rate of spontaneous chromosome doubling was similar in both groups (58% vs. 56%). The results strongly support the notion that winter genotypes are more amenable to androgenesis and this may be a consequence of their better adaptation to stress conditions.     

QTL controlling partial resistance to Stagonospora nodorum leaf blotch in winter wheat cultivar Alba

Stagonospora nodorum blotch (SNB) is an important foliar and glume disease in cereals. Inheritance of SNB resistance in wheat appears quantitative. The development of partially resistant cultivars seems to be the only effective way to combat the pathogen. Partial resistance components like length of incubation period (INC), disease severity (DIS) and length of latent period (LAT) were evaluated on a population of doubled-haploids derived from a cross between the partially resistant cultivar Alba and the susceptible cultivar Begra. Experiments were conducted in controlled environments and the fifth leaf was examined. Molecular analyses were based on bulked segregant analyses (BSA) and screening with 240 microsatellites DNA markers. The QTL analysis revealed QTL on chromosome 6AL (designated as QSnl.ihar-6A) and putative QTL on chromosome 6D. The QSnl.ihar-6A accounted for 36% of the phenotypic variance for DIS and 14% for INC. The putative QTL accounted for 10% of the variability in INC and 8% of DIS components of SNB resistance.     

Bound amino acids in humic acids from arable cropping systems

We investigated the varying concentrations of bound amino acids in humic acids (HA) extracted from soils under both crop rotation and continuous cropping of rye. The experiment was created in 1957. Since then, winter rye had been grown continuously and also the sequence of the 7 yr rotation had been started: potato, spring barley, alfalfa, alfalfa, oil seed rape, winter rye, and winter rye. Soils were fertilized with NPK and manure. Continuous cropping of rye increased total acidity of soils and the contents of carboxylic and phenolic groups in HA. The total amounts of the bound amino acids in HA from soils under crop rotation were higher than from continuous cropping of rye. Fertilization with NPK increased the contents of bound amino acids more than manure. Neutral amino acids dominated in all samples of HA, and basic amino acids had the lowest concentrations. In both types of cultivation, glutamic acids, glycine, alanine, valine, and lysine dominated. The proline contents in HA from continuous rye cropping were higher than in HA from soils under crop rotation. The concentrations of β‐alanine and lysine were higher in HA from crop rotation indicating a higher microbial biomass since these compounds are typical constituents of bacteria cell walls.     

Design,Evaluation and Application of a Continuously Stirred Tank Reactor System for Use in Nitric Acid Air Pollutant Studies

Nitric acid (HNO₃) vapor is a significant component of air pollution. Dry deposition of HNO₃ is thought to be a major contributor to terrestrial loading of anthropogenically-derived nitrogen (N), but many questions remain regarding the physico-chemical process of deposition and the biological responses to accumulation of dry-deposited HNO₃ on surfaces. To examine these processes experimentally, a continuously stirred tank reactor (CSTR) fumigation system has been constructed. This system enables simultaneous fumigation at several concentrations in working volumes 1.3 m dia by 1.3 m ht, allowing for simultaneous fumigation of many experimental units. Evaluation of the system indicates that it is appropriate for long-term exposures of several months duration and capable of mimicking patterns of diurnal atmospheric HNO₃ concentrations representative of areas with different levels of pollution.     

The Effect of Chloride on Yield and Nutrient Interaction in Greenhouse Tomato (Lycopersicon Esculentum Mill.) Grown in Rockwool

The effect of increasing chloride content in nutrient solution on nutrient composition in root environment, interaction of nutrients in leaves and yield of greenhouse tomato cv. ‘Grace F₁’ grown in rockwool were searched. In Experiment I (2004–2005) the levels of 15, 30, 60, and 90 mg Cl·L^?1 but in Experiment II (2006) 30, 60, 90 and 120 mg Cl·L^?1 of nutrient solution were tested. The sources of chloride were water (9.6–10.7 mg Cl·L^?1) and calcium chloride (CaCl₂·2H₂O) but the rest of nutrients and sodium in all treatments were on the same levels. It was found that increasing content of chloride from 15 to 60 mg Cl·L^?1 enhanced the total and marketable fruit yield. Within the range of 60 to 90 mg Cl·L^?1 the yield was on the optimum level but the content of 120 mg Cl·L^?1 declined it. Increasing chloride content in the nutrient solutions was reflected in rising of chlorine content in leaves. The concentration of chloride above 60 mg C·L^?1 reduced the content of nitrogen but above 90 mg C·L^?1 declined the content of calcium, sulfur and zinc in leaves. The antagonism between Cl:N, Cl:Ca: Cl:S and Cl:Zn was appeared. More variable interaction were between Cl:K and Cl:B. At the low levels of chloride, from 15 to 60 mg Cl·L^?1, potassium and boron content were decreased but at the higher ones, from 90 to 120 mg·L^?1, these nutrients had increasing course. It was not found out the effect of chloride contents on macro and microelement contents in nutrient solution emitted from drippers however their content upraising in root medium (rockwool). The highest increase was found out for Na 95.1 and 64.9 % (Exp. I and II - respectively), next for Ca (76.0, 70.1 %), Cu (62.5 and 71.0 %), Cl (43.6, 24.4), B (33.3, 21.0 %), N-NO₃ (30.4, 49.6 %), Zn (29.5, 32.8 %), S-SO₄ (25.9, 25.5 %), K (24.5, 24.1 %), Fe (19.8, 19.2 %), Mn (17.5, 21.3 %) and Mg (14.9, 11.7). Advantageous effect of chloride on tomato yield justified the need to introduce for the practice adequate chlorine nutrition, and recommend to maintain 60 to 90 mg Cl·L^?1 in nutrient solution. The best yield appeared when content of chlorine in leaves (8th or 9th leaf from the top) was in the range 0.48-0.60 % of Cl in d. m.     

Mercury content and its bioconcentration factors in wild mushrooms at Łukta and Morag,northeastern Poland

Total concentrations of mercury were determined using cold-vapor atomic absorption spectroscopy (CV-AAS) in the fruiting bodies of 16 species of wild mushrooms and underlying soil (0-10 cm) substrates collected in the areas of the Communes of Morag and ?ukta in the county of Ostróda in northeastern Poland in 1997-1998. A total of 174 composite samples of caps, 174 stalks, 80 whole fruiting bodies (collectively 1254 specimens), and 252 soils were examined. Among several species of mushrooms analyzed, the greatest concentrations were between 1300 and 71000 ng.g(-1) of dry matter. These levels were found in the caps of Sweating mushroom (Clitocybe rivulosa), King Bolete (Boletus edulis), and Common Puffball (Lycoperdon perlatum) and also were characterized by the highest bioconcentration factors (BCF) for Hg, which ranged between 160 +/- 82 and 110 +/- 34. The cap to stalk quotient for mercury concentrations was approximately 2 for most of the species except Poison Pax (Paxilus involutus), which had a greater concentration in caps than in stalks and a quotient of 4.4 +/- 7.2. Hg concentrations in the underlying soil substrates (0-10 cm layer) ranged between 21 +/- 21 and 390 +/- 130 ng.g(-1) of dry matter. The results showed that the consumption of mushrooms, considered to be the sole dietary source of mercury at the highest or mean element concentrations found, is not hazardous at daily ingestion rates of less than 70 and 210 g of fresh product, which would result in a hazard index value of less than unity.