One of the main causes of common ash decline is the impact of heavy metals and salts accumulated in the soil. Furthermore, harmful chemical compounds contribute to the development of abnormalities in the morphogenesis of plant cells. Studies in natural conditions (in vivo) were conducted to select common ash populations with the highest resistance to salts (NaCl) at varying concentrations and heavy metals such as zinc (Zn), cadmium (Cd), and chromium (Cr). The studies were conducted to facilitate the precise and rapid assessment of the harmful substances impact on the plants health from a given population. Saplings from three populations originating from different geographical and climatic regions in southern and southeastern Poland. To ensure the full multidimensionality of the studies, experiments were also conducted under controlled laboratory conditions (in vitro). The in vitro seedlings grown under sterile conditions, served as a reference pattern with the best physiological. The in vitro plants were used for comparison with saplings grown in vivo. To determine the effect of selected abiotic factors on the saplings, measurements were taken of chlorophyll fluorescence parameters, the maximum quantum yield of photosystem II (Fv/Fm), the maximum efficiency of the water-splitting complex on the donor side of PSII (Fv/Fo), and the time to reach maximum chlorophyll fluorescence (Tfm) for both in vivo and in vitro plants. The studies showed that the values of the parameters studied varied depending on the geographical origin of the studied populations. The analyses of the Fv/Fm and Fv/Fo parameters of individual ash populations showed that the in vivo saplings population from southeastern Poland had the lowest resistance to Zn and Cd. In turn, Zn was the compound that caused the greatest disruptions in Fv/Fm and Fv/Fo functioning in in vivo saplings across all the studied populations. The analysis of the Tfm parameter showed that all toxic substances significantly affected the development of disturbances in the photosynthetic system of all saplings populations examined. The obtained results will help foresters in breeding healthy and resistant saplings and increasing the species population using both in vivo and in vitro methods, taking into account the influence of climate on resistance and the development of adaptive capacity of common ash saplings to the effects of soil contamination.

Hericium erinaceus is a fungus that, in addition to its health-promoting properties (including regenerative properties for gastrointestinal membranes and support for neuronal regeneration in neurodegenerative diseases such as Parkinson’s disease), has the ability to synthesize valuable metabolites, such as flavonoids (polyphenols) and terpenoids. These compounds possess strong biocidal properties. These substances provide the growing H. erinaceus mycelium with protection against colonization by other species of rot fungi, such as Trametes versicolor. For these reasons, the biological compounds produced by H. erinaceus can be used to produce ecological fungicides, which will find innovative applications in protecting forest tree seedlings. It should also be emphasized that valuable fungal substances are synthesized primarily by the mycelium of H. erinaceus during the initial stages of its development. Therefore, we undertook to develop an updated and modernized methodology for cultivating H. erinaceus mycelium in the laboratory, with the goal of commercializing the production of this mycelium, which will be used to isolate fungicidal substances metabolized by the fungus cultures. The biocidal substances obtained will be used to produce innovative fungicides in order to protect forest tree seedlings. The studies were conducted using various types of nutrient media, including Potato Dextrose Agar (PDA), Malt Extract Agar (MEA), and wort medium, at various temperatures ranging from 15 °C to 25 °C. Simultaneously, experiments were conducted using solidified media with a pH ranging from 4.0 to 7.0. The research was also expanded to include the growth and execution of experiments using a processed wood substrate, namely, sawdust made from individual structural wood elements. The sawdust was prepared from the bark, sapwood, and heartwood of sessile oak. The PDA medium was more favourable to the mycelium growth of H. erinaceus at 25 °C. It was also found that an acidic pH in the range of 4.0–5.0 significantly influenced the changes in the growth rate of the mycelium species and their phenotype. It was observed that mycelial growth on a substrate of oak sawdust made from sapwood resulted in intensive mycelial growth and a significant reduction in the wood substrate compared to sawdust made from bark, heartwood, and a mixture of all types of sawdust. The reason for the low mycelial growth, low mass reduction and slight reduction in the mass of sawdust made from bark, heartwood, and a mixture of all types of sawdust was the presence of high levels of tannins, which inhibited the fungal growth.