In plants cultivation, some species influencing each other in a favorable manner, and others adversely affect the result of the release of physiologically active substances. These substances, called allelopathic compounds are excreted primarily by underground and aboveground plants’ organs or formed during the decomposition of their remains. Allelopathins show the inhibitory or stimulating effects on the processes of seed germination, growth and physiological activity of plants. The aim of the study was to determine the allelopathic effects of aqueous extracts from the peppermint (Mentha × piperita L.) leaves at various concentrations (1, 3, 5, 10, 15%) on seeds germination and the selected physiological processes of common sunflower (Helianthus annuus L.) seedlings. Seeds were germinated and plants were grown under greenhouse conditions for 30 days. Germination of sunflower seeds was reduced and electrolyte leakage from seedlings increased with increasing concentrations of aqueous extracts of the peppermint leaves. Increasing concentrations of aqueous extracts of peppermint also caused decrease of chlorophyll a and an increase of chlorophyll b content. The highest increase of the maximum photochemical efficiency of photosystem II was observed in H. annuus L. treated with 15% peppermint extract in comparison to the lower concentration of extracts and to the control. Non-photochemical and photochemical quenching and vitality index of hotosystem II decreased with increasing concentrations of allelopathic substances in peppermint extracts.
Plants are exposed to various stress factors which might lead to structural damage and physiological function abnormalities. Drought is one of the environmental stress factors that reduce the productivity of plants. The aim of our study was to determine the influence of drought stress induced by mannitol (-0.5 and -1.5MPa) on selected physiological processes in Z. mays L. In the first stage we studied the effect of mannitol on the germination. In the second stage the effect of mannitol on the growth of plants germinated on distilled water and watered with mannitol in growth phase were measured. Mannitol, which decreased the water content in a concentration-dependent manner, had an inhibitory effect on germination and growth of seedlings and adult plants. Electrolyte leakage of cell membranes of the Z. mays seedlings showed high disturbances in the functioning of the membrane structures in the osmotic drought conditions. Similar results were obtained for maize roots, shoots and leaves in both treatment studies. Chlorophyll content showed only significant differences in plants from treated during the growth phase. Drought stress caused a decrease in chlorophyll content by almost a half compared to the control plants. Measurements of chlorophyll fluorescence of plant leaves from the second stage of experiments showed changes in fluorescence activity parameters Fv/Fm, NPQ, Rfd, qP, ect.; gas exchange measurements also showed changes in activity in each of the two phases.
the target group of students of gymnasiums and secondary schools in the regions where national parks are located and outside these regions. In all the analysed countries we used a questionnaire, which was distributed among 1301 students. For each respondent, answers were entered in a spreadsheet and statistically analysed. The following non-parametric statistical tests were used: Kruskal-Wallis, Friedman, Wilcoxon and parametric ANOVA. The best results were noted among students from Poland and the Czech Republic. In other countries of the Visegrád Group therefore it is appropriate to introduce actions aiming at increasing the ecological awareness of students, according to the models of education functioning in national parks and schools in Poland and the Czech Republic. It is also necessary to revise the ways in which national environmental education exists in all studied countries, as well as to strengthen volunteer activities.
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