Nanoparticles, due to their extensive production and application, can have significant consequences for the environment, including soil and plant pollution. Therefore, it is very important to assess how nanoparticles will affect plants depending on the exposure pathways. The effect of gold nanoparticles in a concentration range of 1–100 mg/L on Mentha spicata L. during a 28-day experiment was investigated. Two routes of nanoparticles exposure were applied: root and foliar. Transmission electron microscopy was used to characterize nanoparticles and their effect on plant leaves’ ultrastructure. Gold content in soil and plant segments was determined using k0-neutron activation analysis. For root exposure, gold was mainly accumulated in soil (15.2–1769 mg/kg) followed by root systems (2.99–454 mg/kg). The maximum accumulation of gold in leaves (5.49 mg/kg) was attained at a nanoparticle concentration of 100 mg/L. Foliar exposure resulted in the maximum uptake of gold in leaves (552 mg/kg) and stems (18.4 mg/kg) at the highest applied nanoparticle concentration. The effect of nanoparticles on the Mentha spicata L. leaves’ biochemical composition was assessed. Nanoparticles affected the content of chlorophyll and carotenoids and led to an increase in antioxidant activity. Root exposure to gold nanoparticles resulted in an increase in the number of starch grains in chloroplasts and also suppressed the activity of the soil microbiota. Gold extraction from mint leaves into herbal infusion varied from 2 to 90% depending on the concentration of nanoparticles in the solution and the exposure route. The health risk as a result of gold exposure via herbal tea intake was assessed through estimated daily intake. The hazard quotient values were found to be less than the cutoff, indicating that a cup of tea infusion should not cause a serious impact to human health.

Metal nanoparticles are increasingly used in industry and agriculture to enhance crop yields and combat plant diseases. Their widespread application has led to exposure across all ecosystem components, including humans. However, there is a lack of a comprehensive assessment of the effect of copper nanoparticles on spearmint plants, applied in different ways (root and foliar) in a wide range of concentrations. The effect of copper nanoparticles at the concentration range of 1–100 mg/L on Mentha spicata L. plants under root exposure and foliar spraying conditions was studied during a 28-day experiment. Copper content in soil and spearmint segments was determined using inductively coupled plasma atomic emission spectroscopy, while the morphology of nanoparticles was characterized using transmission electron microscopy. Foliar spraying showed an inverse relationship between the concentration of copper in solution and root uptake. The highest copper uptake in roots of 27.51 mg/kg was attained at a nanoparticle concentration of 1 mg/L. Root exposure inhibited soil microbial activity, with copper mainly accumulating in soil (up to 950.2 mg/kg) and roots (up to 150.5 mg/kg). Both application methods stimulated pigment production and antioxidant activity, with root irrigation showing a more pronounced effect. Copper extraction efficiency varied (3–64%) depending on exposure method and concentration, raising concerns about transfer along the food chain. Health risk assessment associated with consumption of herbal infusions, prepared from copper-contaminated spearmint leaves, did not show adverse effects when copper levels in the infusion remained below 1.53 mg/L.

The release of nano-sized metal particles into the environment, along with the associated risk of their migration through the food web, is linked to the widespread application of nanomaterials in industry and agriculture. In this study Mentha spicata L. plants were exposed to silver nanoparticles (1–2 nm) at concentrations of 1, 5, 10, 50, and 100 mg/L over a 28-day period, employing two distinct application methods: root application and foliar spraying. Silver content in plant tissues, soil samples, and herbal infusions prepared from exposed spearmint leaves was determined via atomic absorption spectrometry. In root-applied treatments, silver predominantly accumulated in the soil; however, translocation to the leaves was also detected, reaching a maximum concentration of 16.9 mg/kg in leaves at the highest exposure level (100 mg/L Ag nanoparticles). Silver nanoparticles significantly reduced the soil basal respiration rate compared to the control on the 7 and 30 days of incubation. When silver nanoparticles were applied to the foliage, accumulation in the leaves (5.04–140.4 mg/kg) was observed, alongside excretion through the root system into the rhizosphere (up to 2.41 mg/kg). Interestingly, silver nanoparticles enhanced photosynthetic efficiency in the plants by increasing β-carotene and chlorophyll content, and they also stimulated higher antioxidant activity compared to untreated plants. During brewing, silver extraction into the infusion was below 1% for soil-applied treatments but ranged from 22 to 98% for foliar applications. Risk assessment indicated that prolonged consumption of mint infusion containing silver concentrations exceeding 0.348 mg/L could pose adverse health effects.

Background: Medicinal plants are natural sources of bioactive compounds whose therapeutic properties have been recognized for millennia. Among these, mustard stands out due to its wide range of biological properties, being used as an expectorant, analgesic, antibacterial, antioxidant, digestive stimulant, and diuretic. Mustard cultivation is influenced by several risk factors, including soil quality, susceptibility to diseases common to other crops, pest pressure, and occasionally reduced seed germination capacity. The aim of this study was to evaluate the potential of three Pseudomonas bacterial strains as plant growth-promoting agents for mustard, with the objective of improving seed germination and supporting plant development under cultivation constraints. Materials and methods: mustard seeds were treated with suspensions of Pseudomonas fluorescens CNMN-PsB-01, CNMN-PsB-02, and CNMN-PsB-12, cultivated in King B liquid medium. Results: The treatment of mustard seeds led to increases in seed germination, seedling length, and dry weight by 11.6-15.0%, 16.0-18.7%, and 20.0-22.9%, respectively, compared with the control. In addition, total chlorophyll content - particularly chlorophyll b - increased significantly. In the most effective treatments (Pseudomonas fluorescens CNMN-PsB-02 and Pseudomonas fluorescens CNMN-PsB-12), chlorophyll b content was 52.6-71.8% higher than in the control. An increase in chlorophyll content in mustard leaves has important physiological and agronomic implications, as this pigment plays a central role in photosynthesis. Elevated chlorophyll levels, especially chlorophyll b, enhance the efficiency of light energy capture. Consequently, an intensified photosynthesis leads to greater production of assimilates necessary for plant growth and development, which likely explains the observed stimulation of mustard growth. In mustard, enhanced photosynthetic activity may contribute to faster leaf development and improved formation of reproductive organs. Plants with a well-developed photosynthetic apparatus can sustain active metabolic processes for longer periods, providing a competitive advantage. Furthermore, increased chlorophyll content may reflect improved mineral nutrition, particularly with respect to nitrogen and magnesium - key elements in the chlorophyll molecule. Thus, the stimulation of chlorophyll biosynthesis may serve as indirect evidence of enhanced nutrient uptake and utilization. Conclusion: The tested Pseudomonas spp. strains demonstrate significant potential as growth promoters for mustard. Their application improves seed germination, plant growth, and chlorophyll content, thereby contributing to increased productivity and resilience under variable environmental conditions.

Background: Fusariosis is a widespread infection by fungi of the genus Fusarium, affecting a wide range of crops and causing significant economic losses in global agriculture. Biological control using antagonistic microorganisms represents an effective and environmentally friendly strategy for managing fusariosis. In particular, bacteria are known for their ability to secrete fungicidal compounds while promoting root growth, to compete for iron, and to induce systemic resistance in plants. Conventionally, microorganisms with antifungal activity are identified through in vitro screening on agar media. However, this approach does not account for the influence of the host plant on microbial activity at the initial screening stage. Since environmental conditions can significantly affect microbial behavior, this may lead to the selection of strains that are active only in the absence of plants or the rejection of those that exhibit activity only in their presence. The aim of this study was to develop a method for evaluating antimicrobial activity in the presence of agricultural plants and to compare the results with those from conventional screening. Materials and methods: Wheat seeds (cv. Moldova 16), a highly phytopathogenic strain (Fusarium solani CNMN-FF-07), and four bacterial strains from the National Collection of Non-pathogenic Microorganisms (Bacillus cereus var. fluorescens CNMN-BB-07, Bacillus velezensis CNMN-BB-31, Pseudomonas fluorescens CNMN-PsB-01, and CNMN-PsB-02) were used as experimental materials. The bacterial strains exhibited antimicrobial activity against the phytopathogen, as determined by the agar block method, with inhibition zones of up to 23 mm. Results: As a result, a novel methodology was developed for screening microorganisms capable of protecting plants against Fusarium infections. The method involves the germination and growth of bacterized seeds in test tubes containing semi-solid Knop agar medium. The treated seeds were placed on the surface of the medium, after which different concentrations of the phytopathogen were applied dropwise onto the seeds. The test tubes were subsequently sealed with air-permeable cotton plugs and incubated at room temperature for up to 14 days. Conclusions: Of all tested bacteria, only Bacillus cereus var. fluorescens CNMN-BB-07 retained its antifungal activity in the presence of the host plant. These results highlight the importance of screening potential biocontrol agents under conditions that include the target plant, thereby ensuring the selection of strains effective in real plant-microbe-pathogen interactions.