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Common thyme (Thymus vulgaris L., Lamiaceae) is regarded as one of the most important aromatic plant used both as a spice and medicine. The aim of this work was to investigate the yield and quality of common thyme grown for a fresh herb, cultivated in the organic farming system, within the temperate climate in Poland. Two methods of cultivation were applied: open field and foil tunnel. Three successive cuts of herb were possible to obtain during vegetation season, from the middle of July until the end of September. The raw material was analyzed for the content of essential oil (by hydrodestillation), phenolic acids and flavonoids according to Polish pharmacopeia (PP 6th). The composition of essential oil was determined by gas chromatography-mass spectrometry (GC-MS). Sensory evaluation was carried out by quantitative descriptive analysis (QDA) with a trained panelist. The yield of fresh herb was visibly higher when regards cultivation under foil tunnel in comparison to open field, reaching up to 6.74 kg FW × 10 m2. The content of essential oil as well as the percentage share of thymol (a dominant constituent, achieving up to 57.08%) decreased with consecutive herbal cuts. The opposite result was observed for phenolic compounds (phenolic acids and flavonoids). It was shown that the amount of flavonoids was similar in both variants of cultivation, while phenolic acids were accumulated at higher level in the open field conditions. Sensory analysis indicated on slight differences in odor and taste attributes, between samples of fresh herb collected from open field and foil tunnel.

Common valerian (Valeriana officinalis L.) is one of the most important medicinal plants, with a mild sedative, nervine, antispasmodic and relaxant effect. Despite a substantial number of studies on this species, the genetic diversity and population structure have not yet been analyzed. Here, we use a next-generation sequencing-based Diversity Array Technology sequencing (DArT-seq) technique to analyze Polish gene bank accessions that originated from wild populations and cultivars. The major and, also, the most astounding result of our work is the low level of observed heterozygosity of individual plants from natural populations, despite the fact that the species is widespread in the studied area. Inbreeding in naturally outcrossing species such as valerian decreases reproductive success. The analysis of the population structure showed the potential presence of a metapopulation in the central part of Poland and the formation of a distinct gene pool in the Bieszczady Mountains. The results also indicate the presence of the cultivated gene pool within wild populations in the region where the species is cultivated for the needs of the pharmaceutical industry, and this could lead to structural and genetic imbalances in wild populations.

Common thyme is regarded as one of the most important culinary plants. The purpose of the work was to determine the intraspecific variability of common thyme with respect to morphological and chemical characters including the content and composition of essential oil and phenolic compounds in the herb. The objects of the study were 12 clones, vegetatively multiplied from randomly selected individual plants of cultivar ‘Standard Winter’. The morphological observations and harvest of raw materials were carried out in the first year plants’ vegetation. The highest differences between clones were on fresh and dry weight of herb (CV = 0.38 and 0.36, respectively), width of leaves (CV = 0.21), and density of glandular trichomes on the abaxial surface of leaves (CV = 0.29). Examined clones were also differentiated as to the chemical features. Essential oil content (performed by hydrodestillation) and composition (by GC-MS and GC-FID) were determined and they ranged from 2.10 to 4.38 g × 100 g−1 DW. Here, thymol, γ-terpinen, and p-cymen were the dominant compounds. Clone no. 4 was distinctive as to the highest content of essential oil followed by the highest share of thymol (54.59%). The total content of phenolic acids and flavonoids (determined according to PPh 6th) also differed among clones (CV = 0.38 and 0.36, respectively). Using a validated HPLC-DAD method, the following compounds were identified: caffeic, rosmarinic, p-coumaric acids, luteolin 7-O-glucoside, naryngenin, and (−)-epicatechin. Here, rosmarinic acid followed by luteolin 7-O-glucoside were present in the highest amounts (611.47–2675.59 and 46.77–325.11 mg × 100 g−1 DW, respectively). The highest differences between clones were the contents of p-coumaric acid (CV = 0.59), luteolin 7-O-glucoside (CV = 0.50) and rosmarinic acid (CV = 0.40). Such a high range of variability can provide problems with raw material standardization. Nevertheless, it opens possibilities for breeders, whereas individual plants/clones may become valuable components for breeding.