Phacelia tanacetifolia Benth. is a melliferous, phytosanitary fodder plant. An important factor in understanding the biology of this plant is to investigate its allelopathic potential. In the experiment conducted here, ×Triticosecale Wittm. cv. Mamut was treated with water extracts from the roots, stems, leaves, and flowers of phacelia at concentrations of 10%, 12.5%, 15%, and control with 0% of extract. After 7 days of exposure, the germination of grains was assessed by analysing, seedling growth, mass parameters, water content, and electrolytes leakage. Aqueous extracts from the stalks, leaves, and flowers of phacelia significantly inhibited kernel germination at a 10% concentration, and from roots at a 12.5% concentration. The elongation growth of triticale seedlings was significantly inhibited by each of the extracts. Extracts from the leaves and flowers caused a significant reduction in fresh mass at a 10% concentration and extracts from the stalks at a 12.5% concentration. A significant reduction in water content was also found in seedlings watered with extracts of 10% from roots, stalks, and leaves and 12.5% from flowers. Extracts from phacelia roots at a 12.5% concentration and extracts from stalks, leaves, and flowers at a 10% concentration significantly increased the leakage of electrolytes. In general, phacelia exhibits allelopathic potential at higher concentrations of extracts.

This study attempts to determine which of the habitats occupied by Filipendula vulgaris creates better conditions for its growth and development. Selected physiological parameters—PSII activity, chlorophyll content, electrolyte leakage, hydrogen peroxide content as well as biomass, the occurrence of mycorrhiza, and soil characteristics—were investigated. Grassland soils had a higher content of macronutrients and a lower concentration of heavy metals. The degree of colonization of F. vulgaris by AMF (Arum type) oscillated around high values in both types of stands. Plants growing on xerothermic grasslands achieved much better fluorescence parameters than those collected from meadows. Similar results were obtained from the analysis of chlorophyll content. The destabilization degree of cell membranes was significantly higher in plants collected in meadows than in grasslands. Biomass analysis showed higher values of these parameters in grassland plants. In the case of the parameters of fluorescence emission, plants growing on grasslands achieved significantly lower values than plants collected from meadows. The analyses carried out showed that better conditions for growth and physiological activity of F. vulgaris are probably associated with grasslands on a calcareous substrate.