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On-site decentralized urban stormwater management has gained significant momentum in urban planning. Recently, vegetated roofs have been recommended as a viable decentralized stormwater management system and nature-based solution to meet the challenge of urban floods. However, as another type of unconventional green infrastructure, vertical greenery systems (VGS), also known as vegetated facades, have received much less research attention. Even though some researchers suggest that stormwater management by VGS is comparable to that of vegetated roofs, empirical evidence to substantiate this claim is limited. In this study, we conducted rain simulations on newly-built vegetation containers with water storage compartments. These vegetation containers were designed to be incorporated into a VGS specifically for stormwater management. We tested variables that could influence water retention efficiency and evapotranspiration of the containers under field conditions, i.e., inoculation of plant growth-promoting microbes (PGPMs) (Rhizophagus irregularis and Bacillus amyloliquefaciens), different substrate types (sandy loam and reed-based substrate), simulated rain quantity, natural precipitation, substrate moisture, and air temperature. The inoculation of PGPMs significantly reduced runoff quantity from the vegetation containers. Meanwhile, the well-ventilated sandy-loam substrate significantly reduced the remaining water in the water storage compartments over 1-week periods between rain simulation events, achieving high water-use efficiency. The selected microbes were established successfully in the containers and promoted the growth of 2 out of 5 plant species. R. irregularis colonization responded to substrate type and host plant species, while B. amyloliquefaciens population density in the substrate did not respond to these factors. Environmental conditions, such as antecedent substrate moisture, air temperature, and natural precipitation also influenced the efficiency of stormwater retention and/or evapotranspiration. In conclusion, this study provides instructive and practical insights to reduce urban flood risk by using VGS.

Aims Plant Growth-Promoting Rhizobacteria (PGPR) support plant growth by alleviating plant stresses, among which those triggered by saline soils. We isolated Stenotrophomonas sp. SRS1 from salt-resistant Carex distans (distant sedge) roots to understand how this growth promotion was enabled and whether an active contribution of the bacteria and/or plant was required. Methods Various growth assays were used to analyze the effect of bacterial inoculation on Arabidopsis thaliana and Solanum lycopersicum (cherry tomato MicroTom) growth. Furthermore, droplet microfluidics, bacterial genome mining, and bacterial and plant gene expression analysis combined with plant mutant analysis were used for in-depth analysis. Results SRS1 application enhanced plant growth in both saline and nonsaline environments. The fresh weight of SRS1-inoculated plants was higher than that of noninoculated plants, whereas the fresh weight ratio between SRS1-inoculated and noninoculated plants differed whether the plants were grown on agar plates, white sand or in soil. We demonstrated that the strain grew well in high salt-containing media and that, besides plant-growth-promotion-related genes, the bacterium contained various active stress genes. Interestingly, inoculation with the strain increased the induction of plant genes related to abscisic acid and auxin signaling pathways under saline conditions. Conclusions SRS1 inoculation promoted the growth of Arabidopsis and MicroTom tomato under saline and nonsaline conditions, also when the plants were grown in white sand and potting soil. Overall, genetic traits related to stress alleviation, derived from both the bacteria and the plants, play a crucial role in the impact of this novel PGPR strain on plant performance.