Investigating the toxicological effects of aged nanoplastics (NPs) in soil is critical, as UV irradiation may exacerbate their ecological toxicity by altering surface properties and enhancing interactions with the soil. Here, we investigated the effects of different concentrations of pristine and aged polystyrene (PS) and carboxylpolystyrene (PSC) NPs on lettuce and soil properties. Both pristine and aged NPs inhibited pigment synthesis and lettuce growth. The maximum growth inhibition rates of leaf (root) biomass were 10.2 % (23.4 %) and 32.7 % (45.3 %) for pristine PS and PSC (50 mg center dot L- 1) and 26.7 % (35.9 %) and 43.1 % (57.8 %) for aged PS and PSC (50 mg center dot L- 1), respectively. NPs induced excessive reactive oxygen species (ROS) production in the leaves and roots, antioxidant defense mechanisms, and oxidative damage, which was more pronounced with aged NPs. ROS accumulation gradually increased with aging time and concentration of NPs, which inhibited photosynthesis and decreased biomass. At the same aging duration, exposure to either pristine or aged NPs significantly reduced soil pH. Compared to the control, neither pristine nor aged NPs altered the composition of dissolved organic matter, whereas aged PSC induced a significant increase in the intensity of soluble microbial byproducts; this was attributed to differences in soil acidity and alkalinity. Low concentrations of pristine and aged NPs increased the Chao 1 index in soils, exhibiting hormesis, and altered relative microbial abundances. Pristine and aged PS/ PSCs promoted microbial oxidative phosphorylation, carbon fixation pathways in prokaryotes, and the tricarboxylic acid cycle. The results provide critical insights into the impacts of NPs on plant and soil microbial growth.

PurposeThis study aims to investigate the effects of root exudates on the aggregate stability and permeability of loess and to further reveal the mechanisms of vegetation in preventing and controlling soil erosion beyond mechanical effects.Materials and methodsWetting tests were conducted to investigate how loess aggregate stability varies with curing time and root exudate concentration; and infiltration tests were carried out to examine the influence of root exudates on the infiltration characteristics of loess with varying degrees of compaction.Results and discussionThe results showed that the stability of loess aggregates significantly increased due to the application of root exudates. Curing could enhance the stabilizing effects of root exudates on loess aggregates; however, there existed a critical curing duration. The application of root exudates reduced the stable infiltration rate and hydraulic conductivity of loess. However, untreated specimens under lower degrees of compaction exhibited lower stable infiltration rate and hydraulic conductivity due to local structural damage. The stable infiltration rate of both treated and untreated specimens decreased with curing time.ConclusionsThe effects of root exudates can be attributed to their ability to function as stabilizing agents and promote aggregation, due to their high adsorption capacities and negatively charged groups on their surfaces. On the other hand, the presence of root exudates can significantly enhance the soil microbial activity, the microorganisms and their hyphae further strengthen the soil structure, fill pores and increase the soil hydrophobicity, thereby improving the aggregate stability while reducing the soil permeability.

Microplastics (MPs) are an emerging global change factor with the potential to affect key agroecosystem services. Yet, MPs enter soils with highly variable properties (e.g., type, shape, size, concentration, and aging duration), reflecting their heterogeneous chemical compositions and diverse sources. The impacts of MPs with such varying properties on agroecosystem services remain poorly understood, limiting effective risk assessment and mitigation efforts. We synthesized 6315 global observations to assess the broad impacts of microplastic properties on key agroecosystem services, including crop productivity and physiology, soil carbon sequestration, nutrient retention, water regulation, and soil physical and microbial properties. MPs generally caused significant declines in aboveground productivity, crop physiology, water-holding capacity, and nutrient retention. However, the direction and magnitude of these effects varied considerably depending on the specific properties of MPs. The hazards posed by MPs to aboveground productivity, antioxidant systems, and root activity were size- and dose-dependent, with larger particles at higher concentrations inducing greater damage. Prolonged microplastic exposure impaired crop photosynthesis and soil nutrient retention, but most other ecosystem services (e.g., belowground productivity, antioxidant systems, and root activity) showed gradual recovery over time. Fiber-shaped MPs positively influenced crop aboveground and belowground productivity and soil carbon sequestration, potentially due to their linear configuration enhancing soil aggregation and connectivity. Polymer type emerged as the most prominent driver of the complex and unpredictable responses of agroecosystem services to MPs, with biodegradable polymers unexpectedly exerting larger negative effects on crop productivity, root activity, photosynthesis, and soil nutrient retention than other polymers. This synthesis underscores the critical role of microplastic properties in determining their ecological impacts, providing essential insights for property-specific risk assessment and mitigation strategies to address microplastic pollution in agroecosystems.

The use of chemical pesticides in agriculture leads to the accumulation of harmful compounds in soil and plants that can cause diseases of humans and animals. The biological method of plant protection is a promising alternative to chemical pesticides. The purpose of this study was to analyze the antagonistic activity of the Acinetobacter sp. GET13 strain against common bacterial and fungal pathogens of plant diseases in in vitro and in planta experiments. As a result, the effect of the bacterium on the growth of phytopathogenic bacteria (Clavibacter michiganensis, Erwinia carotovora, Pectobacterium carotovorum and Pseudomonas syringae), as well as phytopathogenic fungi (Helminthosporium sativum, Piricularia oryzae.) that cause serious damage to agriculture, was studied. To confirm the results obtained in these experiments, an in planta experiment was conducted on Phaseolus vulgaris (L.) The effectiveness of Acinetobacter GET13 strain for plant protection against phytopathogens was proved based on the results of taking into account the linear function between weight and volume parameters of plants at the end of the experiment. Therefore, this strain has the potential to create a biological product.

The growth of different grafted guava was different as affected by grafting on different rootstock varieties, which also influenced the damage degree of Spodoptera litura larvae. The co-regulation of the pest gut by rhizosphere microorganisms and root exudates may contribute to this differential damage. In this study, the microorganisms of soil, plants, S. litura larvae and root exudates of guava grafted on different rootstock varieties were analysed and compared. The activities of superoxide dismutase, peroxidase and catalase in the midgut of S. litura larvae feeding on heterograft leaves of guava (where rootstock and scion are of the different variety) were significantly higher than those in the midgut of S. litura larvae feeding on homograft leaves of guava (where rootstock and scion are of the same variety), and glutathione s-transferase activity showed an opposite result. Enterococcus spp. and Escherichia spp. were the two bacterial genera with the greatest difference in abundance in the midgut of S. litura larvae and exhibited a negative correlation with each other. The root system of guava influenced the root structure, soil nutrients and the population structure and diversity of rhizosphere microorganisms by regulating the type and amount of root exudates. Root exudates also influenced the physiological and biochemical status of S. litura larvae by regulating the rhizosphere microorganisms driving the tritrophic interaction of plant-microbes-insects. Based on our results and the observed differences in pest occurrence among different grafted plants, improving varieties through grafting may become an effective strategy to reduce the impact of insect pests on guava.

China has significant mineral resources, but prolonged extraction has caused considerable environmental degradation. Interactions among rhizosphere, phyllosphere, and soil microorganisms, along with host plants, are essential for supporting plant growth and increasing stress tolerance. This study employed high-throughput sequencing to assess microbial diversity and community structure related to four common tree species in the mountainous areas of Shanxi Province, with samples collected from three regions over two seasons and three locations. The dominant fungal and bacterial phyla identified were Ascomycota, Basidiomycota, Mortierellomycota, Pseudomonadota, Actinobacteriota, Gemmatimonadota, Acidobacteria, Myxococcota, and Firmicutes. Alpha-diversity analysis revealed that Taiyue Mountain exhibited the highest fungal diversity among the plots, while Liushenyu displayed the highest bacterial diversity. Alpha-diversity was greater in spring than in summer across the seasons. Significant differences in Alpha-diversity were observed among different tree species, with Betula platyphylla showing the lowest diversity. In comparison to phyllosphere microorganisms, rhizosphere and soil microorganisms exhibited higher diversity, richness, and evenness. Beta-diversity analysis indicated significant differences in fungal and bacterial community composition between spring and summer samples, as well as among samples from leaves, roots, and soil. The assessment of soil physicochemical properties and redundancy analysis demonstrated that soil moisture content and organic matter were key factors influencing the composition of fungal and bacterial communities. These findings provide valuable insights into the structural changes in plant microbial communities in mining areas and the restoration of damaged ecosystems.

Salt stress threatens global food security, and although plant growth-promoting rhizobacteria (PGPR) can boost plant resistance and productivity, their field effects are poorly understood. Therefore, this experimental trial explored the mechanisms of PGPR-induced salt stress resistance on ion homeostasis, the photosynthetic system, enzymatic activities, and rhizosphere diversity in rice. The study was conducted in the first week of May 2022, using rice (Tongxi 945) seeds, which were pelleted at the seedling nursery and cultivated in the field under salinity conditions (0.5 and 2.35 g kg- 1) with (+) or without (-) PGPR treatment. Na+/K+ concentrations, photosynthetic, leaf water potential, enzymatic activities, and changes in rhizosphere microorganisms were measured at the heading stage of rice. The findings of this study revealed that salinity stress significantly increased Na+ concentrations in leaves (257.70%), the leaf Na+/K+ ratio (567.96%), and leaf water potential (63.47%) while markedly reducing the net photosynthetic rate (71.72%), stomatal conductance (81.36%), thousand-grain weight (2.22%), and yield (114.15%). However, the application of PGPR mitigated the adverse effects of salinity stress by reducing Na+ concentrations in roots (45.22%) and leaves (26.20%), the root Na+/K+ ratio (64.68%), and leaf water potential (31.39%). PGPR also significantly improved the net photosynthetic rate (29.75%), stomatal conductance (46.89%), transpiration rate (25.56%), and chlorophyll content (11.95%). Applying PGPR significantly enhanced antioxidant enzyme activity, regulated carbon metabolism, increased microbial diversity in rhizosphere soil, and boosted the abundance of dominant fungal genera, alleviating salt stress damage to rice. Overall, PGPR improves microbial diversity, photosynthesis, and enzyme activities, mitigating salt stress effects. Further research is necessary to implement these findings in agriculture and evaluate their long-term impacts on crop productivity and soil health.

Antimony smelting activities damage the soil and vegetation surroundings while generating economic value. However, no standardized methods are available to diagnose the extent of soil degradation at antimony smelting sites. This study developed a standardized framework for assessing soil quality by considering microbial-induced resilience and heavy metal contamination at Xikuangshan antimony smelting site. The soil resilience index (SRI) and soil contamination index (SCI) were calculated by Minimum Data Set and geo-accumulation model, respectively. After standardized by a multi-criteria quantitative procedure of modified Nemerow's pollution index (NPI), the integrated assessment of soil quality index (SQI), which is the minimum of SRINPI and SCINPI, was achieved. The results showed that Sb and As were the prominent metal(loid) pollutants, and significant correlations between SQI and SRI indicated that the poor soil quality was mainly caused by the low level of soil resilience. The primary limiting factors of SRI were Fungi in high and middle contaminated areas, and Skermanella in low contaminated area, suggesting that the weak soil resilience was caused by low specific microbial abundances. Microbial regulation and phytoremediation are greatly required to improve the soil quality at antimony smelting sites from the perspectives of pollution control and resilience improvement. This study improves our understanding of ecological effects of antimony smelting sites and provides a theoretical basis for ecological restoration and sustainable development of mining areas. (c) 2024 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Subsidence from coal mining is a major environmental issue, causing significant damage to soil structure. Soil microorganisms, highly sensitive to environmental changes, adapt accordingly. This study focused on four areas of the Burdai coal mine: a non-subsidence area (CK), half-yearly (HY), 1-year (OY), and 2-year (TY) subsidence areas. Using high-throughput sequencing and molecular ecological network analysis, we examined soil microbial community diversity and structure across these zones, exploring microbial community assembly and functional predictions. Results showed that compared to the control, subsidence areas experienced reduced soil water content, organic matter, available phosphorus, and alkaline nitrogen, with the lowest levels observed at 1 year. These values began to rise after 1 year, suggesting natural recovery after subsidence stabilized. Microbial communities were closely related to soil organic matter, water content, and alkaline nitrogen. At the 1-year mark, soil property changes significantly reduced microbial diversity, which then began to recover after 2 years. The microbial network during 1-year subsidence was simpler, with 102 nodes, 179 edges, and an average degree of 3.51, indicating that early subsidence was unstable, and the microbial community was still adapting. By 1 year, community structure and interactions had begun to stabilize. Stochastic processes played a key role in microbial variability during short-term subsidence.

Ensuring food security through sustainable systems remains a key goal for the agricultural sector. However, poor crop management practices in recent decades have caused significant ecological harm, evidenced by climate change impacts, soil degradation, and water scarcity. Biotic and abiotic stresses during crop development further reduce yield and quality. Reviving traditional farming practices, such as the milpa system, offers a solution to boost production sustainably while repairing past damage. This comprehensive polyculture system centers on maize, intercropped with beans, squash, chili, fava beans, and other crops. Ecologically, milpas enhance biodiversity, improve soil physicochemical properties, and mitigate environmental harm through beneficial interactions among plants, insects, and microorganisms. This work examines these interactions, with a focus on the role of beneficial microorganisms in reversing environmental damage and revitalizing milpa systems. Adopting these tools can strengthen traditional practices, promoting sustainability and ensuring food security.