The environmental benefits of agroforestry systems are well known. However, current knowledge of potential allelopathic interactions is inadequate. The decrease in soil fertility, the increasingly rhapsodic distribution of precipitation, and the special metabolism and cultivation of medicinal and aromatic plants are all harbingers of medicinal-agroforestry systems. The authors aimed to discover the allelopathic effects of Juglans regia L. and Populus tremula L. on germination of medicinal and aromatic plants cultivated in a temperate zone. Accordingly, an in vitro germination trial was conducted with leachates of these trees and two juglone concentrations. These allelopathic effects were evaluated for germination vigour, germination rate, and total fresh weight of seedlings of twelve different species. A pronounced species specificity was observed in tolerance of seeds and seedlings to the allelopathic effect of Populus and Juglans. In four of the species studied, the allelopathic effect may inhibit germination, but only initially. Poppy and angelica proved to be the most sensitive to the treatments. The following species had relative tolerance to the allelochemicals, so further research under natural conditions is suggested for: Althea officinalis L. (9.34 ± 5.04–68.66 ± 13.62 GR%), Anethum graveolens L. (12.00 ± 2.00–100.00 ± 6.12 GR%), Cannabis sativa L. (72.66 ± 9.02–91.34 ± 1.16 GR%), Dracocephalum moldavica L. (38.00 ± 2.00–80.00 ± 17.44 GR%), Linum usitatissimum L. (44.66 ± 2.00–58.00 ± 3.46 GR%), and Satureja hortensis L. (52.00 ± 28.22–82.00 ± 8.00 GR%). The aim would be to introduce them into agroforestry systems.

Summary Introduction: Irrigation plays an important role in the cultivation of medicinal plants. There is a lack of information on intraspecific variability of reactions to the effect of drought. Objective: The aim of the current study was to test the effect of irrigation on four sweet basil (Ocimum basilicum L.) cultivars (‘Genovese’, ‘Kasia’, ‘Keskenylevelű’, ‘Wala’). Methods: In an open field experiment irrigated and non-irrigated treatments were set. Plants were harvested in full flowering stage. Before the harvest, the stomatal conductance and chlorophyll content were measured. The production-related parameters were recorded. In the plant material the glandular hair density, essential oil content and composition (GC-MS) and volatile composition (SPME-GC-MS) were identified. Results: Stomatal conductance of the irrigated plants was 2.5–4.5 times higher than in the non-irrigated ones. The chlorophyll content showed only slight changes. The irrigation had a positive effect on the production. The leaf to stem ratio was not modified by the watering. Irrigation negatively influenced the glandular hair density and the EO content, however it increased the EO yield by 40–129%, depending on the cultivar. Significant compositional changes were registered only in the EO of cultivar ‘Kasia’ for linalool, 1,8-cineole and tau-cadinole ratios. Conclusion: Irrigation increases the biomass and EO yield of basil while the composition of the EO is mostly unchanged. Only slight differences were observed among the cultivars.

No abstract

Nigella sativa L. (black cumin) is well known for its benefi ts in the fi eld of traditional medicine. The aim of this study was to determine the chemical composition and investigate the antimicrobial activity of cold pressed oil (CO) and essential oil (EO) of Nigella sativa L. on food-borne pathogenic and spoilage bacteria. The microdilution method was used to determine the minimal inhibitory concentration (MIC) of Nigella sativa crude oil (CO) and essential oil (EO) against 4 Gram-positive (Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, and Listeria monocytogenes) and 3 Gram-negative (Salmonella Hartford, Pseudomonas aeruginosa, and Escherichia coli) foodborne pathogenic and spoilage bacteria occurring in food products. Total fatty acid composition of CO was analysed by GLC, while the EO was analysed by GC-MS to detect its active compounds. The results showed that the major fatty acid of CO was palmitic acid (C16:0), as saturated fatty acid, however, linoleic acid (C18:2) was the main unsaturated fatty acid. The major compounds of the EO were p-cymene and thymoquinone. The inhibition on all tested bacteria of EO was 10 times higher than of CO, and the lowest concentration value was observed in case of Bacillus subtilis (0.003%). Hence, results reinforce the ambition to apply Nigella sativa oils in food as natural preservative.

The aim of the experiment was to investigate the effect of the level and timing of watering on the productivity and chemical constituents of garden thyme (Thymus vulgaris L., cultivar 'Varico 3') at growth stage (GS) 202 based on the extended BBCH scale in growth chamber for 13 weeks. Different irrigation regimes have been applied based on the soil water content (SWC%) as follows: 1) control (C: 1-13th weeks -70% SWC), 2) mild drought stress (S1: 1-4th weeks -70% SWC, from the 6th week, continuously decreasing drought stress to 40% DVD for 10-13th weeks), 3) sudden drought stress (S2: 1-9th weeks -70% SWC, 10-13th weeks -40% DVD), and 4) constant drought stress (S3: 1-4th weeks -70% DVK, 5-13th weeks -40% SWC). At the end of the experiment, it was determined that water deficiency induced no direct impact on the width and height of garden thyme plants, while internode and shoot lengths were affected significantly. The plants grown under constant drought stress (S3) conditions showed the minimum values concerning lengths (internode 1.30 cm, shoot 7.12 cm), while the highest ones (internode 2.50 cm, shoot 22.08 cm) were found in the control treatment. However, water supply had no significant effect on the shoot number and chlorophyll content of the leaves. The impact of drought stress both on rosmarinic acid and total phenolic content (TPC) was significant and showed the highest values in the S2 and S3 treatments: S2 had the highest rosmarinic acid concentration of 4.61%, and S3 had the highest total phenolic concentration of 0.75 mg GAE ml -1 . A similar result was found for antioxidant capacity in the S3 treatment, where plants reached the highest values (275.44 mg AAE g -1 dry weight), while the total flavonoid content was not significantly affected by different water supply levels. The results show that not only the level of water deficiency but also the change in water supply and the timing of the drought may have a significant effect on the quantity and quality of garden thyme production.