Zahra Karimian

Given the increasing scarcity of potable water and the rising generation of domestic and industrial wastewater, the reuse of greywater to meet part of plant water requirements, along with its environmentally friendly approach, has gained increasing attention. The present study was conducted in 2023 to investigate the effects of microorganisms and biochar on the establishment and growth of Crassula capitella Thunb., as well as on greywater treatment. Cyanobacteria (C0, C0.4, and C0.8 g), mycorrhiza (M0, M5, and M10 g), and biochar (B0, B5, and B10 g) were evaluated under two irrigation regimes including municipal water (MW) and greywater (GW) within a green wall system in Mashhad, Iran. The results indicated that the combined treatments and irrigation water type had statistically significant effects on most of the measured traits. The C0.4–M10–B0 treatment increased chlorophyll content by more than 97% (from 4.93 to 9.74 µg g⁻¹ FW), while the C0–M10–B5 treatment increased RFW and RDW by 189 and 298%, respectively (from 2.530 to 7.309 g and from 0.353 to 1.407 g), compared to their respective minimum values. The initial wastewater COD (376 mg/L) was 118% greater than the COD measured after treatment with C0.4–M10–B0 (173 mg/L). Overall, the C0–M10–B5 and C0.4–M10–B0 treatments showed superior performance in improving plant establishment and growth of C. capitella in the green wall system, while the C0.4–M10–B0 and C0.4–M5–B5 treatments were more effective in greywater treatment. Based on these findings, the integrated use of cyanobacteria, mycorrhizae, and biochar may contribute to the establishment of Crassula in green wall systems and to urban water resource management under the conditions tested in Mashhad, Iran. However, further studies are needed to assess the applicability of these results to other cities or environmental conditions.

Using nanofertilizers in certain concentrations can be a novel method to alleviate drought stress effects in plants as a global climate problem. We aimed to determine the impacts of zinc nanoparticles (ZnO-N) and zinc sulfate (ZnSO₄) fertilizers on the improvement of drought tolerance in Dracocephalum kotschyi as a medicinal-ornamental plant. Plants were treated with three doses of ZnO-N and ZnSO₄ (0, 10, and 20 mg/l) under two levels of drought stress [50% and 100% field capacity (FC)]. Relative water content (RWC), electrolyte conductivity (EC), chlorophyll, sugar, proline, protein, superoxide dismutase (SOD), polyphenol oxidase (PPO) and, guaiacol peroxidase (GPO) were measured. Moreover, the concentration of some elements interacting with Zn was reported using the SEM-EDX method. Results indicated that foliar fertilization of D. kotschyi under drought stress with ZnO-N decreased EC, while ZnSO₄ application was less effective. Moreover, sugar and proline content as well as activity of SOD and GPO (and to some extent PPO) in treated plants by 50% FC, increased under the influence of ZnO-N. ZnSO₄ application could increase chlorophyll and protein content and PPO activity in this plant under drought stress. Based on the results, ZnO-N and then ZnSO₄ improved the drought tolerance of D. kotschyi through their positive effects on physiological and biochemical attributes changing the concentration of Zn, P, Cu, and Fe. Accordingly, due to the increased sugar and proline content and also antioxidant enzyme activity (SOD, GPO, and to some extent PPO) on enhancing drought tolerance in this plant, ZnO-N fertilization is advisable.

Background: The use of organic nanoparticles to improve drought resistance and water demand characteristics in plants seems to be a promising eco-friendly strategy for water resource management in arid and semi-arid areas. This study aimed to investigate the effect of chitosan nanoparticles (CNPs) (0, 30, 60 and 90 ppm) on some physiological, biochemical, and anatomical responses of Salvia abrotanoides under multiple irrigation regimes (30% (severe), 50% (medium) and 100% (control) field capacity). Results: The results showed that drought stress decreases almost all biochemical parameters. However, foliar application of CNPs mitigated the effects caused by drought stress. This elicitor decreased electrolyte conductivity (35%), but improved relative water content (12.65%), total chlorophyll (63%), carotenoids (68%), phenol (23.1%), flavonoid (36.4%), soluble sugar (58%), proline (49%), protein (45.2%) in S. abrotanoides plants compared to the control (CNPs = 0). Furthermore, the activity of antioxidant enzymes superoxide dismutase (86%), polyphenol oxidase (72.8%), and guaiacol peroxidase (75.7%) were enhanced after CNPs treatment to reduce the effects of water deficit. Also, the CNPs led to an increase in stomatal density (5.2 and 6.6%) while decreasing stomatal aperture size (50 and 25%) and semi-closed stomata (26 and 53%) in leaves. Conclusion: The findings show that CNPs not only can considerably reduce water requirement of S. abrotanoides but also are able to enhance the drought tolerance ability of this plant particularly in drought-prone areas. Graphical

Salt stress is a serious problem in urban landscape of arid and semi arid regions. To overcome the adverse impacts of salinity, the application of organic matter and plant nutrients in the growth media for improving of plant growth is essential. An experiment was conducted in order to determine the response of Salvia splendens to salinity levels and also the role of humic acid in the salt stress alleviation. In the current experiment five salinity (0, 20, 40, 60, and 80 mM NaCl) and three humic acid (0, 100, 500 and 1000 mg l−1) treatments were prepared. The effects of these treatments were investigated on some growth parameters, physiological characteristics and also biochemical compounds. The results indicated that the growth parameters decreased in saline-treated plants than control plants. Different salinity levels significantly affected relative water content, evaporation rate and also electrolyte leakage. Salinity caused the increase in proline, malondialdehyde, sugar content, DPPH, total phenol content and decrease in chlorophyll, compare to the control plants. Application of humic acid on Salvia splendens, decrease leaf area and plant height compared to the control plants. Thus, regarding the growth parameters, it is probable that the effect of humic acid on the biochemical compounds is similar to salinity effect. The findings suggest that Sage is a sensitive ornamental plant to salinity and humic acid (in the studied levels) could not alleviate the negative effects of salt stress on this plant.

Various planting designs behave in different ways on microclimate and thermal comfort due to mainly distinct features of vegetation type and ratio. The papers simulated the microclimate behavior and thermal comfort of different planting design scenarios of an urban park using ENVI-met model. We measured temperature, relative humidity and wind velocity during the coldest period of 2016. Seven scenarios of planting design with different types and ratios of vegetation were simulated. In scenario of evergreen trees, humidity was relatively high while temperature and wind velocity were decreased. Simulated grass covered park and deciduous trees showed higher temperature and wind velocity. Scenario of grasses and the scenarios with high ratio of deciduous trees in comparison with other scenarios indicated lower wind speeds. The findings can be seen as a possibility of improvement of winter thermal comfort, considering a proper planting design as an important step in order to achieve Citizen Satisfaction.