Effect of microplastics used in agronomic practices on agricultural soil properties and plant functions: Potential contribution to the circular economy of rural areas.

The extensive use of plastic materials and their improper disposal results in high amounts of plastic waste in the environment. Aging of plastics leads to their breakdown into smaller particles, such as microplastics (MPs) and nanoplastics. This research investigates plastics used in agricultural practices as they contribute to MP pollution in agricultural soils. The distribution and characteristics of MPs in agricultural soils were evaluated. In addition, the effect of MPs on soil properties, the relationship between MPs and metals in soil, the effect of MPs on the fate of pesticides in agricultural soils and the influence of MPs on plant growth were analysed, discussing legume, cereal and vegetable crops. Finally, a brief description of the main methods of chemical analysis and identification of MPs is presented. This study will contribute to a better understanding of MPs in agricultural soils and their effect on the soil-plant system. The changes induced by MPs in soil parameters can lead to potential benefits as it is possible to increase the availability of micronutrients and reduce plant uptake of toxic elements. Furthermore, although plastic pollution remains an emerging threat to soil ecosystems, their presence may result in benefits to agricultural soils, highlighting the principles of the circular economy.

Weed interference with peppermint (Mentha x piperita L.) and spearmint (Mentha spicata L.) crops under different herbicide treatments: effects on biomass and essential oil yield.

BACKGROUND: 'Minor crops' such as spearmint and peppermint are high added value crops, despite the fact that their production area is comparably small worldwide. The main limiting factor in mint commercial cultivation is weed competition. Thus, field experiments were carried out to evaluate the effects of weed interference on growth, biomass and essential oil yield in peppermint and spearmint under different herbicide treatments. RESULTS: The application of pendimethalin and oxyfluorfen provided better control of annual weeds resulting in higher crop yield. Additionally, when treated with herbicides both crops were more competitive against annual weeds in the second year than in the first year. All pre-emergence herbicides increased biomass yield, since pendimethalin, linuron and oxyfluorfen reduced the density of annual weeds by 71-92%, 63-74% and 86-95%, respectively. Weed interference and herbicide application had no effect on essential oil content; however, a relatively strong impact on essential oil production per cultivated area unit was observed, mainly due to the adverse effect of weed interference on plant growth. CONCLUSION: Considering that pendimethalin and oxyfluorfen were effective against annual weeds in both spearmint and peppermint crops, these herbicides should be included in integrated weed management systems for better weed management in mint crops. © 2017 Society of Chemical Industry.

Response of Purslane Plants Grown under Salinity Stress and Biostimulant Formulations.

Purslane has been suggested as an alternative crop suitable for human consumption due to its high content of minerals, omega-3 fatty acids, and several health-beneficial compounds. In this study, we aimed to evaluate the effect of salinity stress (tap water (control), 2000, 4000, 6000, 8000, and 10,000 mg L-1), biostimulant application (putrescine and salicylic acid at 200 mg L-1), and the combination of the tested factors (i.e., salinity × biostimulant application) on the growth and chemical composition of purslane plants (Portulaca oleracea L.) over two growing seasons (2022 and 2023). Irrigation with tap water and putrescine application resulted in the highest plant height, weight of aboveground and underground parts, and number of shoots per plant. In contrast, the lowest values of growing parameters were recorded under severe saline stress (10,000 mg L-1), especially for the plants that were not treated with biostimulants. The same trends were observed for macronutrients (N, P, K), total carbohydrates, total chlorophylls, and vitamin C content in leaves. Moreover, nitrate and proline content was higher in plants grown under salinity stress, especially under severe stress (8000-10,000 mg L-1) without biostimulant application. In general, the application of biostimulants mitigated the negative impact of salinity on plant growth and leaf chemical composition, while the effect of putrescine on the tested parameters was more beneficial than that of salicylic acid. In conclusion, this study provides useful information regarding the use of putrescine and salicylic acid as biostimulatory agents with the aim of increasing purslane growth under salinity conditions.

How Does Domestic Cooking Affect the Biochemical Properties of Wild Edible Greens of the Asteraceae Family?

Wild edible greens are a key ingredient of the so-called Mediterranean diet and they are commonly used in various local dishes in their raw or processed form. Domestic processing of edible greens may affect their nutritional value and chemical profile. In this work, six wild species (e.g., Cichorium spinosum L. (S1); Centaurea raphanina subsp. mixta (DC.) Runemark (S2); Picris echioides (L.) Holub (S3); Urospermum picroides (L.) Scop. ex. F.W. Schmidt (S4); Sonchus oleraceus L. (S5); and S. asper L. (S6)) were assessed for the effect of domestic processing (boiling) on chemical composition and bioactivities. Concerning the chemical composition, glucose, oxalic acid, α-tocopherol, and α-linolenic acid were the most abundant compounds, especially in P. echiodes leaves. After decoction, mainly sugars, tocopherols, and oxalic acid were decreased. The species and processing affected the phenolic compounds content and antioxidant, cytotoxicity, and anti-inflammatory activities. Specific compounds were not previously detected in the studied species, while hydroethanolic extracts contained a higher total phenolic compound content. Hydroethanolic and aqueous extracts were effective towards a range of bacterial and fungi strains. Therefore, the consumption of leaves has health-promoting properties owing to the bioactive compounds and can be integrated into healthy diets. However, domestic cooking may affect the chemical profile and bioactivities of the edible leaves, especially in the case of free sugars and phenolic compound content where a significant reduction was recorded in leaves after decoction. On the other hand, domestic processing could be beneficial since it reduces the oxalic acid content in edible leaves, which is considered an antinutritional factor.

Seed Germination of Three Milk Thistle (Silybum marianum (L.) Gaertn.) Populations of Greek Origin: Temperature, Duration, and Storage Conditions Effects.

Milk thistle besides being a highly competitive weed is cultivated as a medicinal plant, and the seeds of which have been clinically utilized in several disorders caused in liver. The present study aims to evaluate the effect of duration and storage conditions, population, and temperature on seed germination. The experiment was conducted in Petri dishes with three replications and three factors: (a) wild populations of milk thistle (Palaionterveno, Mesopotamia, and Spata) originating from Greece, (b) duration and storage conditions (5 months at room temperature, 17 months at room temperature, and 29 months in the freezer at -18 °C), and (c) temperature (5 °C, 10 °C, 15 °C, 20 °C, 25 °C, and 30 °C). All three factors significantly affected germination percentage (GP), mean germination time (MGT), germination index (GI), radicle length (RL), and hypocotyl length (HL) and significant interactions among the treatments were noted. In specific, no seed germination was recorded at 5 °C, while the populations showed higher GP and GI at 20 °C and 25 °C after 5 months of storage. Prolonged storage negatively affected seed germination although, cold storage mitigated this effect. Moreover, higher temperatures reduced MGT and increased RL and HL with the populations reacting differently in storage and temperature regimes. The results of this study should be taken into consideration when proposing the appropriate sowing date and storage conditions of the seeds used as propagation material for crop establishment. Moreover, the effects of low temperatures such as 5 °C or 10 °C on seed germination as well as the high decline rate in germination percentage over time could be utilized in the design of integrated weed management systems thereby indicating the importance of the sowing time and the suitable crop rotation system to weed control.