Plastic film mulching, widely used in agriculture, leads to microplastic (MP) pollution in soils. While biodegradable polybutylene adipate terephthalate (PBAT) films may offer a solution, their impacts on subsurface soils and microorganisms remain unclear. To investigate the effects of conventional non-biodegradable polyethylene (PE) and biodegradable PBAT MPs on the properties of sub-surface soils and microbial communities, MPs were added at varying doses in a field experiment and incubated for 160 days. Physicochemical characteristics, nutrient dynamics, and microbial composition, diversity, and networks of soils were analyzed using standard techniques and 16S rRNA/ITS gene sequencing. Correlations between soil properties and microbes were assessed. Both MP types significantly altered soil characteristics, with PBAT-MP elevating pH and the levels of available phosphorus and potassium more than PE-MP. Microbial composition shifts occurred, with low-addition PBAT-MP promoting plastic-degrading genera. The assessment of α/β-diversity indicated that PBAT-MP predominantly influenced fungi while PE-MP impacted bacteria. An examination of microbial co-occurrence networks highlighted that PE-MP primarily disrupted fungal interactions, whereas PBAT-MP streamlined network complexity. Correlation analyses revealed that PBAT-MP promoted fungal diversity/network resilience correlating to nutrients. PE-MP and PBAT-MP significantly altered native soil/microbe relationships. PBAT-MP may exert greater, yet unknown, impacts over time through its biodegradation into newer and smaller fragments. Future research needs to integrate multi-omics and stable isotope science to elucidate the deep mechanistic impacts of degraded film-derived MPs on microbial ecological functions and biogeochemical cycles. Attention should also be paid to the long-term accumulation/transport of MPs in agricultural soils. Overall, this work deepens the impact and understanding of MPs from plastic film on sub-surface soil ecology. Furthermore, it provides a theoretical foundation for managing ‘white pollution’ in the film-covered farmlands of arid and semi-arid regions in China.

Drought stress severely limits the productivity of sweet potato (Ipomoea batatas L.), yet the stage-specific molecular mechanisms of its adaptation remain poorly understood. Therefore, we integrated transcriptomics and extensive targeted metabolomics analysis to investigate the drought responses of the sweet potato cultivar ‘Luoyu 11’ during the branching and tuber formation stage (DS1) and the storage root expansion stage (DS2) under controlled drought conditions (45 ± 5% field capacity). Transcriptome analysis identified 8292 and 13,509 differentially expressed genes in DS1 and DS2, respectively, compared with the well-watered control (75 ± 5% field capacity). KEGG enrichment analysis revealed the activation of plant hormone signaling, carbon metabolism, and flavonoid biosynthesis pathways, and more pronounced transcriptional changes were observed during the DS2 stage. Metabolomic analysis identified 415 differentially accumulated metabolites across the two growth periods, with flavonoids being the most abundant (accounting for 30.3% in DS1 and 23.7% in DS2), followed by amino acids and organic acids, which highlighted their roles in osmotic regulation and oxidative stress alleviation. Integrated omics analysis revealed stage-specific regulation of flavonoid biosynthesis under drought stress. Genes such as CYP75B1 and IF7MAT were consistently downregulated, whereas flavonol synthase and glycosyltransferases exhibited differential expression patterns, which correlated with the selective accumulation of trifolin and luteoloside. Our findings provide novel insights into the molecular basis of drought tolerance in sweet potato and offer actionable targets for breeding and precision water management in drought-prone regions.

Sufficient soil moisture is required to ensure the successful transplantation of sweet potato seedlings. Thus, reasonable water management is essential for achieving high quality and yield in sweet potato production. We conducted field experiments in northern China, planted on 18 May and harvested on 18 October 2021, at the Nancun Experimental Base of Qingdao Agricultural University. Three water management treatments were tested for sweet potato seedlings after transplanting: hole irrigation (W₁), optimized drip irrigation (W₂), and traditional drip irrigation (W₃). The variation characteristics of soil volumetric water content, soil temperature, and soil CO₂ concentration in the root zone were monitored in situ for 0–50 days. The agronomy, root morphology, photosynthetic parameters, ¹³C accumulation, yield, and yield components of sweet potato were determined. The results showed that soil VWC was maintained at 22–25% and 27–32% in the hole irrigation and combined drip irrigation treatments, respectively, from 0 to 30 days after transplanting. However, there was no significant difference between the traditional (W₃) and optimized (W₂) drip irrigation systems. From 30 to 50 days after transplanting, the VWC decreased significantly in all treatments, with significant differences among all treatments. Soil CO₂ concentrations were positively correlated with VWC from 0 to 30 days after transplanting but gradually increased from 30 to 50 days, with significant differences among treatments. Soil temperature varied with fluctuations in air temperature, with no significant differences among treatments. Sweet potato survival rates were significantly lower in the hole irrigation treatments than in the drip irrigation treatments, with no significant difference between W₂ and W₃. The aboveground biomass, photosynthetic parameters, and leaf area index were significantly higher under drip irrigation than under hole irrigation, and values were higher in W₃ than in W₂. However, the total root length, root volume, and ¹³C partitioning rate were higher in W₂ than in W₃. These findings suggest that excessive drip irrigation can lead to an imbalance in sweet potato reservoir sources. Compared with W₁, the W₂ and W₃ treatments exhibited significant yield increases of 42.98% and 36.49%, respectively. The W₂ treatment had the lowest sweet potato deformity rate.

Biodegradable film mulching is increasingly used to replace polyethylene in agriculture, but effects on soil respiration (SR) and components remain unclear, especially during degradation. This study investigated biodegradable mulching’s regulation of SR, root-derived respiration (RDR), and non-root-derived respiration (NRDR) under varying phases. A two-year field experiment was conducted in a rainfed maize system in northern China, comparing conventional tillage with biodegradable film mulching (BM), conventional tillage with polyethylene film mulching (PM), and conventional tillage without mulching (CT). Continuous measurements of soil CO₂ concentration (SCC), temperature, water content, and respiration components were used to assess dynamic responses. Results showed that BM enhanced SR and shifted peak timing, with the SR peaking at 106 days after sowing (DAS) under BM, 91.8 DAS under PM, and 91.2 DAS under CT, mainly through a more sustained RDR (BM peak at 103 DAS with a broader peak and greater cumulative RDR than PM and CT). As the biodegradable plastic film degraded, NRDR was higher during the degradation phase, consistent with a priming-like response. These phase-dependent effects suggest that BM first facilitates root growth then serves as a microbial substrate. Moreover, elevated SCC was positively associated with both RDR and NRDR, indicating that CO₂ may function as a regulatory signal rather than a passive byproduct of respiration. These findings reveal distinct temporal mechanisms by which BM influences soil carbon fluxes and offer mechanistic insights into the sustainable application of biodegradable film mulching. Future research should evaluate long-term effects on microbial community composition, soil carbon balance, and potential trade-offs with crop productivity and environmental risks.

Biochar and seaweed fertilizers could improve soil quality and promote plant growth. However, the key soil factors and microbial mechanisms that drive maize growth in coastal saline–alkali soils remain unclear. A soil culture experiment was designed with four treatments—no organic fertilizer (CK), single seaweed fertilizer (F), single biochar (B), and combined application of seaweed fertilizer and biochar (BF)—to investigate the effects of biochar and seaweed fertilizer on maize growth and its mechanism. The results showed that B and BF significantly increased maize aboveground biomass by 8.86% and 17.28% compared to CK, respectively. The soil organic carbon, total nitrogen, available nitrogen, available phosphorus, available potassium content, and pH of B and BF were significantly increased. Bacterial diversity increased under B and BF, while fungal richness decreased under BF. The changes in the fungal community were mainly affected by soil available nitrogen, but there was no significant correlation between bacterial communities and these indicators. Pearson correlation analysis suggested that the bacterial Chao1 index was significantly positively correlated with maize growth indicators, soil available phosphorus, and available potassium, as well as the bacterial PD whole tree index with leaf area and available phosphorus. The fungal Shannon index was significantly negatively correlated with maize plant height, leaf area, SPAD, aboveground biomass, and soil total nitrogen and available nutrients. Overall, biochar and seaweed fertilization could significantly promote maize growth by improving soil chemical properties and microbial communities in coastal saline–alkali soils.

Sweet potato (Ipomoea batatas (L.) Lam.) is an important food crop worldwide, but its production is often constrained by drought and low soil potassium (K)