Phytotoxic substances released by invasive plants have been reported to have anti-pathogen, anti-herbivore, and allelopathic activity. The aim of this study was to determine the allelopathic influence of the Ambrosia trifida L. on oxidative stress parameters (the lipid peroxidation process; reduced glutathione (GSH) content; and activity of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and peroxidase (PX)) and phenolic compounds (total phenolic and tannin content) in maize (Zea mays L.), soybean (Glycine max L.), and sunflower (Helianthus annuus L.) crops to explore the effect of released allelochemicals through A. trifida root on crops. An analysis by HPLC confirmed the presence of protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, and syringic acid as major components in the A. trifida. Based on the obtained results for oxidative stress parameters, it can be concluded that the sunflower was the most sensitive species to A. trifida allelochemicals among the tested crops. The other two crops tested showed a different sensitivity to A. trifida. The soybean did not show sensitivity, while the maize showed sensitivity only 10 days after the sowing.

The aim of this study was to determine the effect of the hydrolates obtained as the by-products of the Thymus vulgaris essential oil steam distillation process. The bioassays, which were undertaken in order to determine the effect on germination and initial growth of seedlings of some cultivated and weed species, were performed under controlled conditions with different concentrations of the hydrolates. Seeds of Glycine max, Helianthus annuus, Zea mays, Triticum aestivum, Daucus carota subsp. sativus, Allium cepa, Medicago sativa, and Trifolium repens, and six weed species—Amaranthus retroflexus, Chenopodium album, Portulaca oleracea, Echinochloa crus-galli, Sorghum halepense, and Solanum nigrum—were treated with 10, 20, 50, and 100% T. vulgaris hydrolate solution. The obtained results showed that the T. vulgaris hydrolate had the least negative effect on the germination of cultivated species, such as soybean, sunflower and maize, whereas clover and alfalfa were the most sensitive. By comparison, all the tested weed species expressed high susceptibility. It can be concluded that the T. vulgaris hydrolate has an herbicidal effect, in addition to its potential as a biopesticide in terms of integrated weed management.

The cereal grains, which represent the cultivated grasses fruits, supply almost half of the total caloric requirements for humans and provide more nourishment compared with any other class of the food. Out of many cereals used for food, maize, rice, and wheat are the most important food resources for humans, representing 94% of the total cereals consumption. According to the data of the Republic Institute of Statistics for the year 2018, the harvested areas of corn amount to 906,753 hectares. The production of about 7 million tons was achieved with an average yield of 7.7 t/ha according to the Ministry of Agriculture of the Republic of Serbia. Serbia is still among the ten largest exporters of wheat and corn in the world for the period of 2014/15–2017/18. More precisely, it ranks seventh in the export of corn. Utilization of maize products for food animal nutrition (1000 t) is 491,48, and for industrial processing (1000 t) 278,862 expressed as the total consumption (1000 t) is 769,910. Therefore, a total of 103 samples of maize products were analyzed for the presence of toxins, i.e., tropane alkaloids (TAs). The samples were collected from the retail stores in the Republic of Serbia in 2021 and analyzed for the presence of atropine and scopolamine (33 corn grits, 39 polenta, and 31 semolina samples). Therefore, the Recommendation 2015/976/EU on the monitoring of TAs in food was adopted by the EU Commission to obtain more occurrence data on TAs in food. The monitoring extent, however, is restricted because reliable analytical methods and appropriate sensitivity are limited. There was a limit of 1 g/kg for each atropine and scopolamine in cereals containing millet, sorghum, buckwheat, or their derivatives. All the samples were analyzed by the LC-MS/MS. The LOQ was set at 1.0 μg/kg. Out of the total 103 tested samples, 32 samples (31.1%) were contaminated with atropine and scopolamine in concentrations above the LOQ. The highest concentrations of the studied TAs were observed in a semolina sample-atropine: 58.80 μg/kg, scopolamine: 10.20 μg/kg. The obtained results indicate that the TAs concentrations are above the LOQ which can be considered potential human and animal health hazards.

The noticeable reduction in plant species abundance near industrial hemp (Cannabis sativa L.) highlights the need to investigate its potential allelopathic effects on selected cultivars’ seed germination and seedling growth. Industrial hemp of the “Helena” variety was used to obtain aqueous extracts by conventional (macerate, hydrolate, and post-distillation residue) and green methods (ultrasonic and microwave extracts) in order to treat thirteen most commonly cultivated plant species, including lettuce, kohlrabi, onion, tomato, carrot, pepper, savoy cabbage, rocket, alfalfa, white mustard, pea, sunflower, and parsley. This is the first time that the allelopathic effects of seven different hemp extracts were tested simultaneously on thirteen different species. The extracts were applied at 10, 25, 50, and 100% concentrations. The seed germination percentage and root/shoot length results for all tested plants, except peas, clearly demonstrated an inhibitory effect of higher concentrations of hemp extracts. This effect was observed regardless of variations in chemical composition (CBD, THC, and total polyphenols), suggesting that different extracts have varying impacts on different species. The weakest inhibitory effect on the germination and seedling length for the majority of the tested plant species was noted for PDR, while the strongest inhibitory effect in terms of seedling length was observed in the case of MAE700.

Asclepias syriaca L. is an invasive plant in Serbia which threatens the biodiversity and ecosystem functionality with its high production of wind-dispersed seeds and the rapid proliferation by the lateral rhizomes. The mechanism that allows its competitiveness is allelopathy - the release of the chemical compounds identified in the roots and leaves which have negative effects on the other plants. These allelochemicals not only affect the development of the neighboring plants, but also are a potential source of the antioxidant and antimicrobial compounds, which increase the immunity of the plant itself, protecting it from the pests and the pathogens. The present study aimed to screen the antifungal activity of the A. syriaca water and methanol extracts. In vitro antimicrobial activity was analyzed by the radial growth assays against the three phytopathogenic fungi isolates: Alternaria alternata, Fusarium avenaceum and Discula platani. The results were processed by factorial ANOVA and the statistically significant differences were determined by Duncan’s multiple range test using the software STATISTICA 13.5. The obtained results suggest that the A. syriaca water extract has a significant fungistatic and potential fungicidal effect towards the tested phytopathogenic fungi and thus can be considered as a potential tool for their biological control.