Ecological characteristics of habitats and occurrence of thymus pulegioides (Lamiaceae) in Lithuania

Thymus pulegioides L. (Lamiaceae) is essential oils bearing, aromatic and medicinal plant of Central Europe, Scandinavia, Baltic States and South East England indigenous flora. The chemical polymorphism of essential oils can subservient to the selection of valuable clones of T. pulegioides as a selection donors from spontaneous populations for the cultivation. T. pulegioides grow in natural and semi-natural meadows, however, intensive agriculture led to decrease of areas of natural grasslands with habitats of T. pulegioides. The objective of study was to evaluate the occurrence of T. pulegioides in habitats belonged to different plant communities, characterize habitats according to soil chemistry and other ecological factors. The analysis of 131 different natural habitats of T. pulegioides showed that the higher total herb cover can influence on decrease of cover-abundance of T. pulegioides (r = -0.24, p 1>2>3 in habitats corresponds to the following vegetation classes Molinio-Arrhenatheretea elatioris > Trifolio-Geranietea sanguinei > Festuco-Brometea erecti > Koelerio-Corynephoretea canescentis, i. e. the higher probable of low coverabundances of T. pulegioides is possible in the habitats belonged to the vegetation class Molinio-Arrhenatheretea elatioris than in the habitats belonged to the vegetation class Festuco-Brometea erecti

Impact of chemical polymorphism of Thymus pulegioides on some associated plant species under natural and laboratory conditions

Allelopathic potential of Thymus pulegioides L. chemical polymorphism was investigated under natural and laboratory conditions. A field analysis of 127 natural habitats hosting chemotypes of T. pulegioides with different ratios of phenolics, geraniol, and ɑ-terpinyl acetate was conducted. Effects of chemotypes, and their main compounds on seed germination and radicle growth of Trifolium pratense L. and Poa pratensis L. were conducted under laboratory conditions. Field analysis showed that Poa species were more plentiful in comparison with Trifolium species, independent of the chemotypical composition of T. pulegioides habitats. Laboratory tests with plant-acceptors showed a stronger inhibitory effect of essential oils on the germination and radicle growth of P. pratensis but in some instances germination was stimulated. Dissimilar effects were observed for the same allelochemical through air and water on the same plant-acceptor. Significantly, different effects of essential oils on radicle growth occurred in T. pratense and P. pratensis: with sensitivity to the phenolic chemotype via air and the ɑ-terpinyl acetate chemotype through water. This demonstrates that chemical polymorphism can expand communication opportunities of T. pulegioides with associated plant species. Combining investigations in natural habitats with laboratory experiments can help understand the effect of chemical polymorphism on plant-plant ecological interactions

Ecological characteristics of habitats and occurrence of thymus pulegioides (Lamiaceae) in Lithuania

Thymus pulegioides L. (Lamiaceae) is essential oils bearing, aromatic and medicinal plant of Central Europe, Scandinavia, Baltic States and South East England indigenous flora. The chemical polymorphism of essential oils can subservient to the selection of valuable clones of T. pulegioides as a selection donors from spontaneous populations for the cultivation. T. pulegioides grow in natural and semi-natural meadows, however, intensive agriculture led to decrease of areas of natural grasslands with habitats of T. pulegioides. The objective of study was to evaluate the occurrence of T. pulegioides in habitats belonged to different plant communities, characterize habitats according to soil chemistry and other ecological factors. The analysis of 131 different natural habitats of T. pulegioides showed that the higher total herb cover can influence on decrease of cover-abundance of T. pulegioides (r = -0.24, p 1>2>3 in habitats corresponds to the following vegetation classes Molinio-Arrhenatheretea elatioris > Trifolio-Geranietea sanguinei > Festuco-Brometea erecti > Koelerio-Corynephoretea canescentis, i. e. the higher probable of low coverabundances of T. pulegioides is possible in the habitats belonged to the vegetation class Molinio-Arrhenatheretea elatioris than in the habitats belonged to the vegetation class Festuco-Brometea erecti

Geraniol and carvacrol in essential oil bearing Thymus pulegioides: Distribution in natural habitats and phytotoxic effect

Phenolic and non-phenolic chemotypes of Thymus pulegioides L. are common in Europe. Essential oils of these chemotypes, as various compositions of allelochemicals, can have different phytotoxic effects on neighboring plants in natural habitats. The aim of this study was to establish the distribution of carvacrol and geraniol in T. pulegioides, growing wild in Lithuania, and compare phytotoxity of essential oils of carvacrol and geraniol chemotypes on selected plant species. In investigating 131 T. pulegioides habitats, essential oils were isolated by hydrodistillation and analyzed by GC-FID and GC-MS. Phytotoxity of essential oils extracted from carvacrol and geraniol chemotypes transmitted through water and air to selected plants was determined under laboratory conditions. Pharmacologically valuable Hypericum perforatum L. and the important forage grass Phleum pratense L. were respectively selected for experimentation from among 35 medicinal plants and 10 feed Poaceae species, growing in T. pulegioides habitats. Field results showed that carvacrol is common throughout Lithuania’s territory, whereas the geraniol is predominantly located under the continental climatic conditions of the eastern region of the country. In the laboratory experi-ment, it was established that there was stronger inhibition of P. pratense seed germination by the essential oil of the geraniol chemotype than the carvacrol chemotype. None of the H. perforatum seeds germinated after exposure to the essential oil of the geraniol chemotype. In general, this study builds on previous studies by providing further evidence that different T. pulegioides chemotypes have contrasting phytotoxic effects on neighboring plants within their natural habi-tats

Disinfecting capacity of essential oil of Thymus pulegioides L. (lamiaceae) chemotypes against phytopathogenic Pseudomonas species

The antibacterial activity of essential oils of T. pulegioides chemotypes — geraniol/geranial/neral (G/G/N), thymol (T) and linalool (L) — was studied against the seven phytopathogenic Pseudomonas species isolated from vegetables. The chemotypes were defined according to their main essential oil components: geraniol, thymol and linalool. The results showed that the essential oil of T chemotype had the strongest anti-Pseudomonas activity: it inhibited the growth of all investigated bacteria up to even 84.4% in comparison with controls. The essential oils of L chemotype inhibited the growth of bacteria less than T chemotype, and G/G/N chemotype proved to be the least effective. These differences of anti-Pseudomonas activity depend on the different chemical composition of essential oils of investigated T. pulegioides chemotypes

Effect of organic matter fertilizers on the composition of volatiles, morphometrical and anatomical parameters of essential oil-bearing Thymus x citriodorus cultivated in an open field conditions

Thymus x citriodorus (Lamiaceae) is medicinal, essential oil-bearing hybrid, synthesizing significant amounts of geraniol. This hybrid is suitable for cultivation in an open ground in the Baltic region; therefore, increasing the yield and amounts of bioactive compounds by organic matter fertilization during organic farming is realized. The aim of the present study was to evaluate the effect of fertilization with liquid cattle dung and humus on the quantitative and qualitative composition of essential oils as well as on biomass for some morphometrical and anatomical parameters of Thymus x citriodorus that were grown in open ground for two years. Each fertilization treatment was carried out on four replications, and four separate experimental plots were used as control plots. For anatomical investigations, the impress method and light microscopy were used. The essential oils were isolated by hydrodistillation and analyzed by GC-FID and GC-MS. The results showed somewhat different effects of liquid cattle dung and humus on the investigated parameters of hybrid in the first (warmer and drier) and second (rainier and cooler) experimental years. Liquid cattle dung had positive effects on biomass, height and the area covered by plants and on the number and length of inflorescences as well as on the density of stomata in the lower epidermis in the first year, but in the second experimental year, effects were observed on the length of inflorescences only. The effect of humus on the density of glandular trichomes in the upper epidermis of leaves was positive in the first year, but negative in the second experimental year. Moreover, in the second experimental year, humus affected negatively the height of plants and the percentage of the essential oil. The conclusion was that although it is fertilized with the same organic fertilizers, different climatic conditions in different years can influence chemical, anatomical and morphometrical parameters of plants growing in an open ground

Impact of edaphic and climatic factors on Thymus pulegioides essential oil composition and potential prevalence of chemotypes

Intraspecific chemical polymorphism is characteristic of essential oil bearing Thymus pulegioides (Lamiaceae). Soil chemical composition and climatic conditions can influence not only quantitative and qualitative composition of essential oils, but also on prevalence of different chemotypes in space. The purpose of study was to determine the impact of edaphic and climatic factors on T. pulegioides essential oil composition and potential chemotypes prevalence. It were investigated 131 habitats of T. pulegioides in all ten climatic sub-districts of Lithuania. Essential oils were isolated by hydrodistillation and analysed by GC-FID and GC-MS. The content of humus was estimated by oxidation method, the content of mobile potassium (K2O) and mobile phosphorus (P2O5)-flame photometry using 0.2 M HCl solution, the soil pH-electrometrically and 15 elements of soil-by energy-dispersive X-ray fluorescence. The meteorological data (temperature, rainfall, photosynthetically active solar radiation and sunshine duration) were obtained from the meteorological bulletins. Results showed that humus in soil positively, manganese and cobalt-negatively influenced on the essential oil accumulation in T. pulegioides. Carvacrol was the most common compound in the essential oil of T. pulegioides; higher amounts of sulphur and mobile phosphorus, lower amounts of sodium in soil, higher rainfall in blooming period are favourable for this compound and for potential prevalence of carvacrol chemotype. Geraniol was frequent in the eastern and the central part of Lithuania, where the temperature in vegetation season is higher, and in soils characterised by higher and lower amounts of sodium and chlorine, respectively. Thymol, linalool and alpha-terpinyl acetate were rare. Edaphic and climatic conditions can differently influence on essential oil yield and chemical composition of species as well as on potential prevalence of different chemotypes of same species in space