Members of the genus Sorbus are the only endemic tree species that occur in Czechia. They are important components of endangered plant communities. Their natural regeneration is usually problematic because of their mode of reproduction and because they can survive in rare populations with small numbers of individuals. The aim of this study was to develop a successful micropropagation protocol for selected Sorbus species, of which two are endemic (S. gemella and S. omissa) and two are hybrid (S. × abscondita and S. × kitaibeliana). We found significant differences in shoot induction and rooting ability between the Sorbus species under study. With the exception of S. × abscondita, N⁶-benzyladenine had a significantly greater effect on shoot regeneration, both in terms of shoot number and total shoot length, than meta-topolin. Root induction was key to the successful micropropagation of the Sorbus species studied. Our results show that four Sorbus species can be successfully rooted under ex vitro conditions, without a rooting powder treatment in a steamed peat-perlite substrate. Auxin-untreated microcuttings of S. gemella, S. × kitaibeliana and S. omissa, but not S. × abscondita, rooted better than ones treated with indole-3-butyric acid. This is the first time a micropropagation protocol for S. omissa, S. × abscondita and S. × kitaibeliana has been published.

The aim of study: (1) to compare the survival rate, growth performance and nutrition of large and common-sized planting stock of rowan (Sorbus aucuparia L.) on a frost-exposed site and (2) to assess whether fertilizing had any effect on the plantations.Area of study: The Jizera Mts., an area heavily disturbed by air pollution situated on the Czech-Polish border close to GermanyMaterials and methods: Two types of planting stock were tested in a mountain frost hollow on an acidic mountain humic podsol: (a) the bare-rooted saplings 131–140 cm tall and (b) common-sized containerized transplants 26–35 cm. One half of the saplings and common-sized transplants were left untreated and the other half were fertilized with a low dose (30 g per tree) of a slow release fertilizer based on methylene urea and potassium magnesium phosphate. Growth performance and nutrition of plantations were investigated.Main results: Due to serious deformations and stem breakages inflicted by snow and frost, the prospects of common-sized transplants seem much worse than those of saplings. The height growth of saplings was significantly more rapid than that of common-sized transplants. As for growth, neither the saplings nor common-sized transplants did significantly respond to fertilizing. The effects of fertilizing on nutrition of rowans were unconvincing. The extreme temperature events during growth seasons and snow deformations in winters might be the decisive factors influencing growth performance of rowans under referred conditions.Research highlights: On the frost-exposed sites, the height of taller saplings might partly compensate for a missing shelter of forest stand since the terminal leaders are above ground-frost zone.Key words: mountain ash; sapling; common-sized transplants; nutritional status; temperature.Abbreviations: CS – Control Saplings; CT – Control Transplants; FS – Fertilized Saplings; FT – Fertilized Transplants

Seasoning Poplar (Populus maximowiczii × Populus nigra ´Max 4-5´) Wood Using Evapotranspiration

Within Phytophthora alni, an invasive pathogen of alders ( Alnus spp.), three species have been identified. The most frequent and pathogenic species is P. × alni. It has a variable intraspecific structure, with dominance of the Pxa-1 genotype and the presence of dozens of rare genotypes (in most cases derived from Pxa-1). Its local populations are highly variable, and their population structure and development remain unknown. We compared two sets of strains isolated from identical sites during the epidemic (2005 to 2010) and post-epidemic (2020 to 2024) phases of the disease in the Vltava River basin (Czech Republic) and studied them using microsatellite marker analysis and fitness tests (sporangia production, growth, and virulence). We acquired 151 P. × alni isolates of 23 multilocus genotypes. We found that during the post-epidemic phase, genetic diversity decreased, and the dominance and incidence of the Pxa-1 genotype increased. Only the dominant genotype (Pxa-1) was repeatedly isolated from the same sites, whereas the rare genotypes were replaced. During the post-epidemic phase, both the incidence of rare genotypes and the degree of their derivation from Pxa-1 decreased. The rare genotypes had lower fitness than Pxa-1 (the more changes there were, the worse the fitness was). These results allow us to hypothesize the evolution of local populations of P. × alni in Europe, as the most pathogenic genotype, Pxa-1, will also prevail during the late phases of the disease, and the risk of further damage to the surviving host populations will persist.

Although transfers and invasions of alien fungi and oomycetes to new environments have ecological and economic impacts comparable to those of plants and animals, their importance has so far been underestimated. Here, we compile accessible records of alien species from these two groups. Extensive research of data across literature, on-line databases, herbaria, and institutional and personal collections has resulted in the first list of alien and cryptogenic fungi and oomycetes for the present-day area of the Czech Republic. A total number of 352 alien taxa recorded in the period 1813–2022 includes 38 archaeomycetes (i.e. species introduced into Europe before 1492), 310 neomycetes, and 4 unranked species. The highest proportion of alien fungi and oomycetes originated from North America, Europe, and temperate Asia. From the taxonomic point of view, ascomycetes represent the highest proportion of alien species, while at the class level, Peronosporomycetes , Dothideomycetes , Leotiomycetes , Pucciniomycetes , Sordariomycetes , and Agaricomycetes are the most frequent. Plant parasites prevail, whereas saprotrophic fungi are less numerous and other ecological groups are rare: six mycorrhizal fungi and two wild animal parasite species have been recorded in the Czech Republic. An assessment of potential risk indicated that numerous species impact (in order of frequency) horticulture, agriculture, and forestry. We identified 56 casually introduced species, 156 naturalised taxa, and 72 invasive species. Significant ecosystem damage may be expected for 36 introduced species, six of which can be classified as transformers. Five species were classified as eradicated. The terminology used in invasive plant and animal biology was adopted, with minor modifications to reflect the specificity of fungi and oomycetes. Natural and geopolitical conditions are discussed and taken into account in the proposed general scheme of invasions of fungi and oomycetes representing an integral part of neobiota and sharing invasion principles and rules with alien macroorganisms.