Background: Drought and heat stress are significant concerns to food security in arid and semi-arid regions, where global warming is predicted to increase both frequency and severity. To cope with these challenges, the use of drought-tolerant plants or technological interventions are essential. In this study, the effects of foliar potassium nitrate (KNO₃) application on the stress tolerance and recovery of Myrobalan 29C rootstocks (Prunus cerasifera Ehrh.) were evaluated. These rootstocks are widely recognized for their adaptability and are extensively used in fruit production. To assess their response, the rootstocks were subjected to drought, heat shock, or a combination of both stressors. Additionally, they were treated with 1.0% KNO₃ via foliar application. Throughout the stress and recovery periods, various morphological, physiological, and bio-chemical parameters were measured. Results: Based on our results, KNO₃ treatment improved LRWC, Chl stability, SC, and key stress markers like proline, MDA, H₂O₂, along with antioxidant enzymes CAT, SOD, POD during both stress and recovery phases. Moreover, our results emphasized KNO₃'s critical role in hormone regulation under stress. KNO₃ application significantly altered hormone levels, notably increasing ABA during drought and heat shock stress, essential for stress response and adaptation. In contrast, IAA, GA, and cytokinin’s significantly increased during the recovery phase in KNO₃-treated plants, indicating improved growth regulation and stress recovery. In addition, KNO₃ application improved the recovery process of the rootstocks by restoring their physiological and biochemical functions. Conclusion: This study suggests that the application of foliar KNO3 is an effective technique for enhancing the drought and heat tolerance as well as the recovery of Myrobalan 29C rootstocks. These results hold significant value for farmers, policymakers, and researchers, as they offer crucial insights into the development of drought-tolerant crops and the management of climate change’s adverse effects on agriculture.

This work aimed to investigate the interaction between salt stress and the application of silicon dioxide-nanoparticles. In this study, gerbera plants grown in soilless culture were supplied with nutrient solutions with different NaCl concentrations (0, 5, 10, 20 and 30 mM) in combination with SiO ₂ -NPs spray (0, 25 and 50 mg · L ⁻¹ ). Exposure of gerbera to salinity increased sodium concentration but decreased potassium and calcium concentrations in leaf as well as stem length/diameter, fresh/dry weight, leaf/flower number, flower diameter and leaf area. It also increased the activities of antioxidant enzymes and electrolyte leakage. Results indicated that SiO ₂ -NPs could improve growth, biochemical and physiological traits. It increased stem thickness but slightly affected stem length. Flower diameter was not affected by salinity rates up to 10 mM of NaCl. However, a significant difference was observed between controls and plants treated with 30 mM of NaCl. Salinity increased the electrolyte leakage (32.5%), malondialdehyde (83.8%), hydrogen peroxide (113.5%), and the antioxidant enzyme activities such as ascorbate peroxidase (3.4-fold) and guaiacol peroxidase (6-fold) where SiO ₂ -NPs activated them more, except for superoxide dismutase. Under salinity (30 mM), the increase in SiO ₂ -NPs (especially at 25 mg · L ⁻¹ ) led to the increase in the uptake of Ca ²⁺ (25.3%) as well as K ⁺ (27.1%) and decreased absorption of Na ⁺ (6.3%). SiO ₂ -NPs has potential in improving salinity tolerance in gerbera. It seems that the sensitivity threshold of gerbera to the salinity was 10 mM and the use of SiO ₂ -NPs is also effective in non-saline conditions.

Background: Chitosan nanoparticles (CTS-NPs) protect the active ingredients from the environment for a specific period and reduces sweating, control weight loss, delay ripening, and increase vase life. So, a factorial experiment was carried out as a randomized complete design in three replications to investigate the efficiency of CTS-NPs in quality improvement and longevity extension of cut rose flowers. Results: The 15-day maximum vase life was attained by the rose placed in a preservative solution containing 10 mg L⁻¹ CTS-NPs. CTS-NPs also reduced microbial growth as compared to controls. Total phenolics, total flavonoids, and amount of anthocyanin in treated petals were dramatically increased. CTS-NPs solutions especially at 10 and 15 mg L⁻¹ concentrations, markedly reduced the H₂O₂ and malondialdehyde at the end of 15th day and maintained the membrane index. The protein and carbohydrate and petals anthocyanin content and enzymatic activities such as superoxide dismutase, polyphenol oxidase, peroxidase, catalase and ascorbate peroxidase increased in cut roses placed in 10 mg L⁻¹ CTS-NPs vase solution which in turn caused to increase in vase life. Conclusion: CTS-NPs especially at a level of 10 mg L⁻¹ can assist plants to enhance light usage efficiency, as well as promote photosynthetic carbon fixation and the production of additional carbohydrate products for plant growth and development. Graphical

Background: Drought stress is a critical environmental factor that disturbs plant performance. However, some non-essential elements such as silicon can improve water deficit tolerance by modulating photosynthesis assimilates and compatible solutes production. Therefore, the present work was conducted to modulate polyethylene glycol (PEG)-induced water deficiency under in vitro culture in Damask rose genotypes (Maragheh and Kashan) by nano-silicon (SiO₂-NPs) treatment. A completely randomized factorial experiment was used as three concentrations of SiO₂-NPs (0, 50, and 100 mg L⁻¹) and five concentrations of PEG (0, 25, 50, 75, and 100 g L⁻¹). Then, the comparative effects of water deficiency on vegetative traits, metabolites, and nutrients were studied. Results: The drought promoted a significant decrease in chlorophyll, fresh/dry weight, biomass, and an increase in electrolyte leakage. The amount of micro- and macronutrients were affected by drought stress and decreased in both genotypes. In contrast, the activity of polyphenol oxidase (PPO) and total phenolic compounds (TPC) along with biochemical traits was increased. Treatment with SiO₂-NPs improved the leaf area index (LAI), chlorophyll, and biomass under severe water deficiency. The concentration of compatible solutes such as carbohydrates, total flavonoid content (TFC), TPC, anthocyanin, and antioxidative capacity enhanced by the application of SiO₂-NPs by about twofolded. As well as an increase in PEG concentration, the absorption of nutritional elements such as P, K, Mn, Fe, Zn, and Cu was decreased. However, SiO₂-NPs application especially at 100 mg L⁻¹ increased the amount of nutrient absorption. Conclusions: In general, the drought tolerance in Damask rose was associated mainly with its suitable manipulation of antioxidant production and orderly enhancement of nutrient adsorption, so that the effect of SiO₂-NPs in improving the qualitative and quantitative characteristics of ʻKashanʼ was more than that of ʻMaraghehʼ. These results briefly highlight that the SiO₂-NPs may provide greater tolerance to drought stress in Damask rose. Graphical

Background: Drought is a major abiotic stress that restricts plant growth and efficiency although some nutrients such as silicon improve drought tolerance by regulating the biosynthesis and accumulating some osmolytes. In this regard, a completely randomized factorial design was performed with three factors including two genotypes (‘Maragheh’ and ‘Kashan’), three concentrations of silicon dioxide nanoparticles (SiO₂-NPs) (0, 50, and 100 mg L^− 1), and five concentrations of PEG (0, 25, 50, 75, and 100 g L^− 1) with three replications.Results: The findings showed that drought stress decreased protein content and it was improved by SiO₂-NPs, so the genotype of ‘Maragheh’ treated with 100 mg L^− 1SiO₂-NPs had the highest protein content. Under severe drought stress, had a higher membrane stability index (MSI) than ‘Kashan’, and the ‘Maragheh’ explants subjected to 100 mg L^− 1SiO₂-NPs exhibited the uppermost MSI. The explants supplemented with 100 mg L^− 1SiO₂-NPs sustained their photosynthetic parameters more in comparison with other treatments under drought stress conditions and as well as 100 mg L^− 1SiO₂-NPs showed higher content of protein and proline of ‘Maragheh’ than ‘Kashan’. Drought stress reducedFm,Fv/Fm, andFv, while SiO₂-NPs treatment enhanced these parameters. SiO₂-NPs also improved water deficit tolerance by enhancing the activity of antioxidant enzymes such as catalase (CAT), peroxidase (POD), guaiacol peroxidase (GPX), and superoxide dismutase (SOD) and reducing lipid peroxidation and H₂O₂concentration.Conclusions: According to the findings, the genotype ‘Maragheh’ was more tolerance to drought stress than ‘Kashan’ by improving water balance, antioxidant enzyme activities, and membrane stability as it was obtained from the unpublished previous evaluation in in vivo conditions and we concluded based on these results, in vitro culture can be used for drought screening in Damask rose plants. The results of the current study revealed that the induced drought stress by polyethylene glycol (PEG) in two Damask rose genotypes was ameliorated with SiO₂-NPs and the tolerance genotypes were better than the sensitive ones in response to SiO₂-NPs treatment.

The preservation of cut flowers, particularly Gerbera jamesonii, is crucial for maintaining their aesthetic value and extending vase life in the floriculture industry. To address this challenge, this study investigated the effects of melatonin (Mel) and encapsulated melatonin with nanochitosan (nCS-Mel) as preservative solutions on cut Gerbera jamesonii cv. ‘Terra kalina’ flowers. In research, we examined various physiological and biochemical parameters, including relative water content, membrane stability index, carbohydrate content, and antioxidant enzyme activities, to evaluate the efficacy of these treatments in prolonging the vase life and quality of cut gerbera flowers under controlled environmental conditions. Our results demonstrated that cut Gerbera jamesonii flowers maintained in vase solutions containing 0.1 and 0.5 mM nCS-Mel exhibited enhanced preservation of cell membrane integrity and anthocyanin content, while also maintaining higher levels of carbohydrates and total flavonoids in petals at the conclusion of their vase life. A decline in petal relative water content and protein levels was observed concomitantly with petal senescence, whereas total phenolic compounds showed an increase. The hydrogen peroxide (H2O2) content in petals exhibited an upward trend during vase life in control specimens, but this effect was mitigated in treatments containing melatonin. Although malondialdehyde (MDA) content generally increased throughout the vase life period, flowers subjected to either Mel or nCS-Mel treatments displayed reduced MDA accumulation. The activity of catalase (CAT) demonstrated an increasing trend during vase life, with the maximum activity observed in Gerbera flowers treated with 0.1 mM nCS-Mel. A similar upward trend was noted for superoxide dismutase (SOD) activity, with flowers in 0.5 mM nCS-Mel treatment exhibiting peak SOD values on day 12 relative to control and other treatments. Peroxidase (POD) activity also increased across all treatments, with particularly pronounced effects in vase solutions containing 0.1 mM Mel and nCS-Mel. Notably, flowers placed in vase solutions containing 0.1 mM nCS-Mel, followed by 0.5 mM nCS-Mel and 0.1 mM Mel, exhibited the most prolonged vase life, extending up to 12, 10.66, and 10.33 days, respectively, under room temperature conditions. The application of nanoencapsulated melatonin as a vase solution for cut Gerbera jamesonii flowers demonstrates significant potential in extending vase life and maintaining flower quality through enhanced preservation of cellular integrity, antioxidant activity, and biochemical parameters. This innovative approach not only outperforms conventional treatments but also presents a more environmentally friendly alternative to traditional antimicrobial preservatives and sugars, offering a promising solution for the floriculture industry to improve cut flower longevity and reduce ecological impact.