Implementation of plant extracts that are rich in phytochemicals and have the allelopathic potential for weed management could help reduce the use of chemical herbicides. The present study investigated the herbicidal potential of walnut (Juglans regiaL.) leaf extract (WLE) against two weeds,Amaranthus retroflexusL. andChenopodium albumL., by testingin vitrotheir seed germination and seedling growth, and then evaluatedin vivothe oxidative stress of potted plants. The effects of the walnut leaf extract were also tested on maize (Zea maysL.) to eliminate possible negative impacts on a cultivated plant. Total phenolic acids and total flavonoid content in the extract were determined in prior bioassays, followed by separation and analysis of flavonoids and phenolic acids by high-performance liquid chromatography (HPLC). Phytochemical analysis revealed that the obtained extract was notably rich in phenolic compounds, while HPLC analysis confirmed the presence of (+)-catechin, luteolin, myricetin, rutin, (–)-epicatechin, genistin, protocatechuic acid, and caffeic acid as major extract components. The results obtained in bioassays revealed a significant negative impact of the walnut leaf extract on germination and seedling growth of the tested weeds, as well as significant oxidative stress in weeds grown in pots. Although it affected the maize seedling growthin vitrosimilar to the tested weeds, maize germination was less sensitive to treatment, and the extract did not have a significant negative impact in terms of oxidative stress in maize plants grown in pots. The findings show that walnut leaf extract may have a promising role in replacing chemical herbicides in maize.

Pesticides are one of the major inputs used for increasing agricultural productivity of crops. However, their inadequate application may produce large quantities of residues in the environment and, once the environment is contaminated with pesticides, they may easily enter into the human food chain through plants, creating a potentially serious health hazard. Nowadays, consumers are becoming more aware of the importance of safe and high quality food products. Thus it is pertinent to explore simple, cost-effective strategies for decontaminating food from pesticides. Various food processing techniques, at industrial and/or domestical level, have been found to significantly reduce the contents of pesticide residues in most food materials. The extent of reduction varies with the nature of pesticides, type of commodity and processing steps. Pesticides, especially those with limited movement and penetration ability, can be removed with reasonable efficiency by washing, and the effectiveness of washing depends on pesticide solubility in water or in different chemical solvents. Peeling of fruit and vegetable skin can dislodge pesticide residues to varying degrees, depending on constitution of a commodity, chemical nature of the pesticide and environmental conditions. Different heat treatments (drying, pasteurization, sterilization, blanching, steaming, boiling, cooking, frying or roasting) during various food preparation and preservation processes can cause losses of pesticide residues through evaporation, co-distillation and/or thermal degradation. Product manufactures, from the simplest grain milling, through oil extraction and processing, juicing/pureeing or canning of fruits and vegetables, to complex bakery and dairy production, malting and brewing, wine making and various fermentation processes, play a role in the reduction of pesticide contents, whereby each operation involved during processing usually adds to a cumulative effect of reduction of pesticides present in the material. There is diversified information available in literature on the effect of food processing on pesticide residues which has been compiled in this article.

The use of Artemisia species’ plant extracts and essential oils, which are rich in bioactive compounds (allelochemicals), could support weed management. This study focused on the chemical analysis and evaluation of the allelopathic potential of plant extracts (PEs) and essential oils (EOs) of Artemisia absinthium and A. vulgaris on the germination and early seedling growth of weeds (Amaranthus retroflexus and Setaria viridis) in vitro. The plant extract from A. vulgaris showed higher antioxidant activity (IC₅₀ = 0.171 ± 0.01 mg/mL) and phenolic content than that from A. absinthium (IC₅₀ = 0.263 ± 0.01 mg/mL). Chlorogenic acid was the most abundant phenol in both extracts. However, A. absinthium contained a higher amount (1.694 ± 0.081 mg/g) and exhibited a stronger inhibitory effect on the germination of A. retroflexus (EC₅₀ = 0.54 ± 0.02%) and S. viridis (EC₅₀ = 1.51 ± 0.07%) compared to A. vulgaris. The dominant components of A. absinthium essential oil were β-thujone (18.9%), cis-ocimene epoxide (7.88%), and bicyclogermacrene (7.04%), while the main constituents of A. vulgaris essential oil included gurjunene (10.41%), cis-crysanthenyl acetate (7.17%), and γ-humulene (6.67%). The lowest EC₅₀ values for A. absinthium essential oil regarding seed germination and seedling length were estimated for S. viridis (0.28 ± 0.48% and 0.03 ± 0.00%, respectively), whereas A. retroflexus was the most sensitive to A. vulgaris essential oil (0.11 ± 0.04% and 0.02 ± 0.00%, respectively). All tested extracts showed allelopathic potential; however, the results indicate that the essential oils had a stronger inhibitory effect than the plant extracts.

Kinetic studies are important for understanding the parameters and processes involved in the sorption of pesticides to soil. Considering the agricultural and environmental relevance of clomazone, its sorption kinetics was studied in four agricultural soils (Regosol, Planosol, Chernozem and Vertisol) at two concentrations (0.5 and 15 mg L⁻¹). Different kinetic models were applied to the experimental data. The pseudo-second-order model described the data much better than the hyperbolic and pseudo-first-order models, and the kinetic rate constants indicated concentration-dependent clomazone sorption kinetics. The application of the two-site nonequilibrium model (TSNE) revealed a more time-dependent sorption of the lower clomazone concentration than that of the higher clomazone concentration, and the greatest concentration impact occurred in Regosol. Elovich and intraparticle diffusion models predicted more intensive sorption during the slower second phase and that sorption kinetics is governed more by mass transfer across the boundary layer than by a intraparticle diffusion process at higher clomazone concentration. Intraparticle diffusion is the rate-controlling process in Regosol at lower concentration, while this process and the boundary layer control the sorption kinetics in other soils. Significant correlations between some kinetic parameters and soil properties indicate an impact of the soil texture on the clomazone sorption mechanism, which must be considered in assessing the clomazone leaching behavior.

The purpose of this study was to examine in vitro the herbicidal effect of an essential oil of dill (Anethum graveolens) on germination and early seedling growth of two parasitic flowering plants in the genus Cuscuta (Cuscuta campestris and C. epithymum), as well as its phytotoxic impact on germination and early seedling growth of two host plants (alfalfa and red clover). Chemical analysis of the essential oil extracted from dill leaves and flowers showed that carvone (51.69%) and limonene (39.88%) predominated. The results of a seed bioassay showed inhibitory effects of different concentrations (1%, 0.5%, 0.1%, and 0.01% v v-1) of the essential oil of dill leaves on germination and early seedling growth of both tested species of the genus Cuscuta. Germination of C. campestris seeds was inhibited between 67% and 94%, while seed germination of C. epithymum was inhibited between 67% and 100%. A similar inhibitory effect was observed regarding the seedling length parameter. Moreover, the bioassay results indicated significant phytotoxic effects of dill essential oil on the seed germination and early seedling growth of host plants. Red clover proved more sensitive as even the lowest concentration inhibited germination by 35%, while higher concentrations caused 70-100% inhibition. On the other hand, lower concentations inhibited germination of alfalfa seeds by 5%, while higher concentrations caused greater inhibition (36-100%). Future research should include both pot experiments and field micro-trials to determine herbicidal, i.e. phytotoxic, effects of dill essential oil on parasitic flowering plants and cultivated species.