Wood biochar in soil enhances the promotion of KNO3 on sulfur accumulation in apple trees by regulating root sulfate assimilation

Impact of microplastics on microbial-mediated soil sulfur transformations in flooded conditions

As emerging environmental pollutants, microplastics have become a crucial focus in environmental science research. Despite this, the impact of microplastics on soil in flooding conditions remains largely unexplored. Addressing this gap, our study examined the influence of polystyrene (PS) and polyphenylene sulfide (PPS) on the microbial populations in black soil, meadow soil, and paddy soil under flooded conditions. Given the significant regulatory influence exerted by microorganisms on sulfur transformations, our study was primarily focused on evaluating the microbial contributions to alterations in soil sulfur species. Our findings revealed several notable trends: In black soil, both PS and PPS led to a marked increase in the abundance of γ-proteobacteria and Subgroup_6, while reducing Clostridia. Ignavibacteria were found to be lower under PPS compared to PS. In meadow soil, the introduction of PPS resulted in increased levels of KD4-96 and γ-proteobacteria, while α-proteobacteria decreased. Chloroflexia under PPS was observed to be lower than under PS conditions. In paddy soil, our study identified a significant rise in Bacteroidia and Ignavibacteria, accompanied by a decrease in α-proteobacteria and γ-proteobacteria. γ-proteobacteria levels under PPS were notably higher than those under PS conditions. These shifts in microbial communities induced by both PS and PPS had a direct impact on adenosine 5'-phosphosulfate reductase, sulfite reductase, and polysulfide dioxygenase. Consequently, these changes led to soil organic sulfur decrease and sulfide increase. This study not only offers a theoretical framework but also provides empirical evidence for understanding the effects of microplastics on soil microorganisms and their role in regulating nutrient cycling, particularly in flood-prone conditions. Furthermore, this study underscores the importance of ensuring an adequate supply of sulfur in agricultural practices, such as rice and lotus root cultivation, to support optimal crop growth in the presence of microplastic pollution.

The impact of microplastics on sulfur REDOX processes in different soil types: A mechanism study

Microplastics can potentially affect the physical and chemical properties of soil, as well as soil microbial communities. This could, in turn, influence soil sulfur REDOX processes and the ability of soil to supply sulfur effectively. However, the specific mechanisms driving these effects remain unclear. To explore this, soil microcosm experiments were conducted to assess the impacts of polystyrene (PS) and polyphenylene sulfide (PPS) microplastics on sulfur reduction-oxidation (REDOX) processes in black, meadow, and paddy soils. The findings revealed that PS and PPS most significantly decreased SO42- in black soil by 9.4%, elevated SO42- in meadow soil by 20.8%, and increased S2- in paddy soil by 20.5%. PS and PPS microplastics impacted the oxidation process of sulfur in soil by influencing the activity of sulfur dioxygenase, which was mediated by α-proteobacteria and γ-proteobacteria, and the oxidation process was negatively influenced by soil organic matter. PS and PPS microplastics impacted the reduction process of sulfur in soil by influencing the activity of adenosine-5'-phosphosulfate reductase, sulfite reductase, which was mediated by Desulfuromonadales and Desulfarculales, and the reduction process was positively influenced by soil organic matter. In addition to their impacts on microorganisms, it was found that PP and PPS microplastics directly influenced the structure of soil enzymes, leading to alterations in soil enzyme activity. This study sheds light on the mechanisms by which microplastics impact soil sulfur REDOX processes, providing valuable insights into how microplastics influence soil health and functioning, which is essential for optimizing crop growth and maximizing yield in future agricultural practices.

Lanthanum Significantly Contributes to the Growth of the Fine Roots' Morphology and Phosphorus Uptake Efficiency by Increasing the Yield and Quality of Glycyrrhiza uralensis Taproots

The occurrence of different degrees of phosphorus deficiency in the vast majority of G. uralensis cultivation regions worldwide is common. There is a pressing need within the cultivated G. uralensis industry to identify appropriate exogenous substances that can enhance the uptake of phosphorus and improve both the yield and quality of the taproots of G. uralensis. This study was conducted to investigate the fine root and taproot morphology, physiological characteristics, and secondary metabolite accumulation in response to the supply of varying concentrations of LaCl3 to G. uralensis, to determine the optimal concentration of LaCl3 that can effectively enhance the yield and quality of G. uralensis's taproots, while also alleviating its reliance on soil phosphate fertilizer. The findings indicate that the foliar application of lanthanum enhanced root activity and increased APase activity, eliciting alterations in the fine root morphology, leading to promoting the accumulation of biomass in grown G. uralensis when subjected to P-deficient conditions. Furthermore, it was observed that the nutrient uptake of G. uralensis was significantly improved when subjected to P-deficient conditions but treated with LaCl3. Additionally, the yield and quality of the medicinal organs of G. uralensis were significantly enhanced.