Urban vegetation can act as an effective sink for airborne particulate matter (PM) in densely populated cities, yet how specific leaf functional traits regulate the retention of different PM size fractions remains poorly resolved. In particular, it is unclear whether fine and coarse particles are governed by similar trait mechanisms under realistic urban roadside conditions. Here, we examined 44 common roadside plant species along roads with contrasting traffic intensity and surrounding land-use characteristics in Nanjing, China. Foliar retention of multiple PM size fractions (total suspended particles, PM >10 μm, PM10-3 μm, and PM3_-1 μm) was quantified using a three-stage membrane filtration method, together with measurements of leaf functional traits and surface micromorphology. PM retention capacity differed significantly among species and life forms (p < 0.05). Retention of coarse particles was primarily associated with structural traits that enhance mechanical interception, whereas fine-particle retention was more strongly linked to micro-scale leaf traits, particularly stomatal width, indicating a clear size-dependent shift in trait importance. Although particle-size distributions varied among roadside environments, trait-PM relationships remained broadly consistent across sites. These findings demonstrate that particulate matter retention by urban vegetation is regulated by distinct, size-dependent trait mechanisms rather than by a uniform set of functional traits. By highlighting functional specialization in plant-PM interactions, the present study provides a trait-based framework for optimizing urban roadside vegetation design according to local pollution profiles and mitigation objectives.

Leaf functional traits are an important part of plant adaptive strategies and respond differently to different environments, but our understanding of how plants adapt to highly complex urban environments through coordinated changes in leaf functional traits is limited. In order to deeply explore the effects of different urban environments on the leaf functional traits of landscape plants, this study focused on ten common landscape plants in Nanjing, specifically, Euonymus japonicus, Pittosporum tobira, Loropetalum chinense, Photinia × fraseri, Acer palmatum, Euonymus japonicus ‘Aurea-marginatus’, Platanus acerifolia, Camphora officinarum, Ginkgo biloba, and Lagerstroemia indica. The study employed one-way analysis of variance (ANOVA), two-way ANOVA, principal component analysis (PCA), and membership function comprehensive evaluation to explore the responses of green space plants to the environments of urban park green spaces (PAR), urban community green spaces (NL), and urban road green spaces (CR) and to analyze the impact of the trade-off strategies of plants in different green space environments based on leaf functional traits. The results showed that plant leaf functional traits and their adaptive strategies varied in different urban environments in Nanjing. The contents of LDMC, MDA, POD, and CAT in the ten plant species followed the order CR > NL > PAR, and SLA, SOD, SS, and total chlorophyll showed trends of PAR > NL > CR. The microstructures of the leaves of the ten plant species, such as SA, TUE, and TS, were evident in the expression of adaptive adjustments to the different green space environments. The principal component analysis and the comprehensive evaluation of the affiliation function of the indicators of the ten plant species revealed that the adaptability of the ten green space plants to the complex urban environment was as follows: Euonymus japonicus ‘Aurea-marginatus’ > Lagerstroemia indica > Acer palmatum > Photinia × fraseri > Platanus acerifolia> Camphora officinarum > Loropetalum chinense > Ginkgo biloba > Euonymus japonicus > Pittosporum tobira. The results of the study will help to further understand the layout, application, and maintenance of landscape plants in the context of urbanization and provide support for related theories.

Efficient cultivation is essential for the rose industry. Both substrate formulation and plant growth-promoting rhizobacteria (PGPR) application both critical, yet their synergistic effects remain limited. This study investigated the synergistic effects of Bacillus subtilis (Bs) and Priestia megaterium (Pm) combined with five substrate formulations on the growth physiology, photosynthetic characteristics, and soil properties of Rosa × hybrida ‘Ruby’. Two-way ANOVA revealed significant interactions between substrate and PGPR treatments for most growth and physiological indicators. Orthogonal experiments demonstrated that specific PGPR–substrate combinations significantly enhanced plant growth and photosynthetic performance of the studied cultivar, as well as soil quality. Principal component analysis and membership function analysis identified four substrate–PGPR combinations as optimal, with the T4 substrate (humus/perlite/vermiculite/coconut coir/peat/biochar = 5:1.5:1:1:1:0.5) showing the most pronounced effects. In this T4 substrate, PGPR inoculation significantly altered the rhizobacterial community structure. LEfSe analysis revealed 67 enriched microbial biomarkers—substantially more than single-strain treatments. The relative abundance of beneficial genera such as Acidibacter and Chryseotalea increased, and the combined bacterial treatment enhanced functional pathways associated with signal transduction, cell motility, and RNA processing. Compared to single-strain treatments, the combined bacterial application demonstrated superior regulatory effects on plant growth. The optimal combined treatments increased plant height by up to 42.7%, root activity by 103.0%, soluble protein content by 302.8%, and soil ammonium nitrogen by 168.8%. These findings demonstrated that tailored combinations of PGPR and cultivation substrates highlight the potential for optimizing rose cultivation and improving the rhizosphere microecological environment.