Environmental issues are a pressing concern for modern societies, and the increasing levels of atmospheric CO₂ have led to global warming. To mitigate climate change, reducing carbon emissions is crucial, and carbon sequestration plays a critical role in this effort. Technologies for utilising CO₂ can be divided into two major categories: direct use and conversion into chemicals and energy, and indirect use as a carbon source for plants. While plants’ ability to absorb and store CO₂ makes them the best CO₂ sink, finding suitable urban areas for significant green spaces is a challenge. Green walls are a promising solution, as they require less land, provide more ecosystem services than horizontal systems do, and can contribute to reducing environmental problems. This study evaluates the conceptual potentials and limitations of urban biomass circulation in terms of energy production, food production, and CO₂ consumption, focusing on growth-promoting bacteria, urban agriculture, and vertical systems. The aim of this research is discovering new methods of carbon sequestration using multi-purpose green walls to achieve sustainable urban development and CO₂ reduction strategies to contribute to a more sustainable future.

Juniperus sabina is an interesting species for forest restoration and ornamental purposes. The seeds of this plant have several types of dormancies; therefore, seed propagation is difficult and time consuming. The production of cuttings can be an alternative way to produce plants more quickly. The main objective of this experiment was to determine the best propagation conditions (indole butyric acid dose, substrate, and season) for this species using stem cuttings. Rooting performance of the cuttings was evaluated based on the rooting percentage (%), root biomass, and specific root length (SRL). In addition, we examined the internal composition (auxin and peroxidase content) in treated stem cuttings. Cuttings were pretreated with five doses of indole butyric acid (IBA; 0 (control), 1000, 2000, 4000, and 8000 ppm) and were rooted in four substrates (perlite, perlite-cocopeat, pumice, and mixed substrate) during the four seasons (winter, spring, summer, and autumn). The best treatments, with more than 60% rooting, were applied in spring, and IBA at 1000 ppm in perlite–cocopeat substrate obtained 62% rooting. The highest rooting percentage correlated with the highest root biomass production and the lowest SRL. IBA pretreatment decreased the concentration of peroxidase in spring (coinciding with maximum rooting), representing an indicator of rooting performance. Based on these results, we recommend a new protocol for Juniperus sabina production: (i) prepare cuttings in spring, (ii) treat cutting bases with 1000 ppm IBA, and (iii) plant cuttings in a substrate of perlite–cocopeat (1:1).

In vitro culture of twin-scaling explants of Galanthus transcaucasicus with different concentrations of plant growth regulators (PGRs) including 0.5, 1, 2, 3, 4, 6, 8, and 10 mg L-1 naphthaleneacetic acid (NAA) and 0.5, 1, 2, 3, and 4 mg L-1 benzyladenine (BA) was studied. After 18 weeks, the number of regenerated bulblets and intensity of callus was measured. Subsequently, bulblets were transferred to a medium with 0.5, 1, 2, 3, and 4 mg L-1 NAA and 0.5, 1, 2, 3, and 4 mg L-1 BA and, after 15 weeks, the bulblets length and diameter were measured. The highest intensity of callus was obtained on 4 mg L-1 NAA or 8 mg L-1 NAA with 1 mg L-1 BA. The highest number of regenerated bulblets was detected with 6 mg L-1 NAA and 2 mg L-1 BA. The highest diameter of bulblets occurred on four mgL-1 NAA (9.4 mm), while the lowest was observed on 0.5 mg L-1 BA (1.83 mm). The analysis of genetic variation using ISSR revealed that there was no somaclonal variation among the regenerated plants from BA and low level of NAA, but there was a significant somaclonal variation at high concentrations of NAA.

Background: Rapid urbanization and population growth exert a substantial impact on the accessibility of drinking water resources, underscoring the imperative for wastewater treatment and the reuse of non-potable water in agriculture. In this context, green walls emerge as a potential solution to augment the purification of unconventional waters, simultaneously contributing to the aesthetic appeal and enjoyment of urban areas. This study aims to optimize water management in green walls by investigating the impact of bacterial strains on the biochemical properties and performance of the ornamental accumulator plant, Aptenia cordifolia, grown with various unconventional water sources. The experiments were designed as split plots based on a completely randomized block design with three replications. The main factor was recycled water with three levels (gray water, wastewater from the Kashfroud region of Mashhad, and urban water (control)). The sub-factor included different bacterial strains at four levels, composed of various bacteria combinations, (B1: Psedoumonas flucrecens + Azosporillum liposferum + Thiobacillus thioparus + Aztobactor chorococcum, B2: Paenibacillus polymyxa + Pseudomonas fildensis + Bacillus subtilis + Achromobacter xylosoxidans + Bacillus licheniform, B3: Pseudomonas putida + Acidithiobacillus ferrooxidans + Bacillus velezensis + Bacillus subtilis + Bacillus methylotrophicus + Mcrobacterium testaceum, and the control level without bacterial application (B0). Result: The findings revealed significant differences at the 5% probability level across all morphophysiological traits, including plant height, the number and length of lateral branches, growth index, and plant coverage. Moreover, superior morphophysiological traits were observed in plants cultivated in substrates inoculated with wastewater irrigation. Substrates inoculated with bacteria exhibited the highest relative water content (RWC) and chlorophyll levels, coupled with the lowest relative saturation deficit (RSD), electrolyte leakage (EL), and carotenoid levels. Furthermore, plant growth-promoting bacteria (PGPB), from a biochemical perspective, were associated with increased carbohydrates, total protein, and anthocyanin. They also contributed to controlling oxidative stress caused by free radicals by enhancing the activity of antioxidant enzymes, such as guaiacol peroxidase (GPX), polyphenol oxidase (PPO), ascorbate peroxidase (APX), and peroxidase (POD), while reducing catalase enzyme (CAT) activity. This led to increased resistance to stress, as evidenced by a decrease in malondialdehyde and proline levels. The study concludes that the MIX B3, being both ecofriendly and economical, represents an effective strategy for mitigating the adverse effects of wastewater on plants. Conclusion: This study showed that plant irrigation using wastewater increases the levels of proline, phenols and oxidative stress. However, the application of plant growth promoting bacteria (PGPB) reduced oxidative damage by increasing antioxidant activity and decreasing proline and phenol levels. These findings show the potential of bacterial treatments to improve plant growth and reduce adverse effects of recycled water irrigation.