The development and production of secondary metabolites from priceless medicinal plants are restricted by drought stress. Mentha pulegium L. belongs to the Lamiaceae family and is a significant plant grown in the Mediterranean region for its medicinal and aesthetic properties. This study investigated the effects of three polyethylene glycol (PEG) (0, 5, and 10%) as a drought stress inducer and four silicon nanoparticle (SiNP) (0, 25, 50, and 100 ppm) concentrations as an elicitor to overcome the adverse effect of drought stress, on the growth parameters and bioactive chemical composition of M. pulegium L. plants grown in vitro. The experiment was performed as a factorial experiment using a completely randomized design (CRD) consisting of 12 treatments with two factors (3 PEG × 4 SiNPs concentrations), 6 replicates were used for each treatment for a total of 72 experimental units.The percentage of shoot formation was inversely proportional to the PEG concentration; for the highest PEG concentration, the lowest percentage of shoot formation (70.26%) was achieved at 10% PEG. SiNPs at 50 ppm enhanced shoot formation, the number of shoots, shoot height, fresh and dry weight, rosmarinic acid, total phenols, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. The methanol extract from M. pulegium revealed the presence of significant secondary metabolites using gas chromatography‒mass spectrometry (GC–MS). The principal constituents of the extract were limonene (2.51, 2.99%), linalool (3.84, 4.64%), geraniol (6.49, 8.77%), menthol (59.73, 65.43%), pulegone (3.76, 2.76%) and hexadecanoic acid methyl ester or methyl palmitate (3.2, 4.71%) for the 0 ppm SiNPs, PEG 0% and 50 ppm SiNPs, and PEG 10%, respectively. Most of the chemical components identified by GC‒MS in the methanol extract were greater in the 50 ppm SiNP and 10% PEG treatment groups than in the control group. SiNP improves drought tolerance by regulating biosynthesis and accumulating some osmolytes and lessens the negative effects of polyethylene glycol-induced drought stress.Based on the results, the best treatment for most of the parameters was 50 ppm SiNPs combined with 10% PEG, the morphological and chemical characteristics were inversely proportional to the PEG concentration, as the highest PEG concentration (10%) had the lowest results. Most parameters decreased at the highest SiNP concentration (100 ppm), except for the DPPH scavenging percentage, as there was no significant difference between the 50 and 100 ppm SiNPs.

In plant production, evaluation of salt stress protectants concerning their potential to improve growth and productivity under saline stress is critical. Bacillus subtilis (Bs) and cobalt (Co) have been proposed to optimize salt stress tolerance in coriander (Coriandrum sativum L. cv. Balady) plants by influencing some physiological activities. The main aim of this work is to investigate the response of (Bs) and (Co) as eco-safe salt stress protectants to resist the effect of salinity, on growth, seed, and essential oil yield, and the most important biochemical constituents of coriander produced under salt stress condition. Therefore, in a split-plot factorial experiment design in the RCBD (randomized complete block design), four levels of salinity of NaCl irrigation water (SA) were assigned to the main plots; (0.5, 1.5, 4, and 6 dS m⁻¹); and six salt stress protectants (SP) were randomly assigned to the subplots: distilled water; 15 ppm (Co1); 30 ppm (Co2); (Bs); (Co1 + Bs); (Co2 + Bs). The study concluded that increasing SA significantly reduced coriander growth and yield by 42.6%, which could be attributed to ion toxicity, oxidative stress, or decreased vital element content. From the results, we recommend that applying Bs with Co (30 ppm) was critical for significantly improving overall growth parameters. This was determined by the significant reduction in the activity of reactive oxygen species scavenging enzymes: superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) and non-enzyme: proline by 5, 11.3, 14.7, and 13.8% respectively, while increasing ascorbic acid by 8% and preserving vital nutrient levels and enhancing plant osmotic potential to buffer salt stress, seed yield per plant, and essential oil yield increased by 12.6 and 18.8% respectively. The quality of essential oil was indicated by highly significant quantities of vital biological phytochemicals such as linalool, camphor, and protein which increased by 10.3, 3.6, and 9.39% respectively. Additional research is suggested to determine the precise mechanism of action of Bs and Co's dual impact on medicinal and aromatic plant salt stress tolerance.

The postharvest life of cut flowers is limited, which is a major challenge and varies greatly depending on plant varieties, cut flower stage, flower length of the harvested shoots, and storage conditions including postharvest treatments. As a result, improving the vase life and quality of cut flowers in regulating postharvest characteristics and overcoming these challenges is critical to the horticulture business. Novel engineered nanocomposites were created and tested for possible impacts on flower bud opening, postharvest life extension, longevity regulation, and preservation and enhancement of the strength and appearance of cut flowers. The experiment was conducted as a factorial experiment using a completely randomized design (CRD) with two factors. The first factor was two holding solutions (without or with sucrose at 20 gL⁻¹). The second factor was 12 pulsing treatments for 24 h; distilled water as a control, 75 ppm GA₃, multi-walled carbon nanotubes MWCNTs at 10, 20, 30, 40, and 50 ppm, and MWCNTs (10, 20, 30, 40, and 50 ppm)/GA₃ (75 ppm) composites; each treatment had 3 replicates, for a total of 72 experimental units. In the present study, gibberellic acid (GA₃) was synthesized in functionalized (MWCNT/GA₃ composites) as a novel antisenescence agent, and their effect on the vase life quality of cut rose flowers Rosa hybrida cv. ‘Moonstone’ was compared by assaying several parameters critical for vase life. The adsorption of GA₃ on MWCNTs was proven by performing FTIR spectroscopy which ensures that the formation of the MWCNTs/GA3 composite preserves the nanostructure and was examined by high-resolution transmission electron microscopy (HR-TEM). The results revealed that sucrose in the holding solution showed a significant increase in fresh weight, flower diameter, and vase life by 10.5, 10.6, and 3.3% respectively. Applying sucrose with MWCNTs 20 ppm/GA₃ 75 ppm composites or MWCNTs 20 ppm alone, was critical for the significant increase in flower opening by 39.7 and 28.7%, and longevity by 34.4 and 23.2%, respectively, and significantly increased chlorophyll a, b, total chlorophyll, anthocyanin, total phenolic content, and 2,2-Diphenyl-1-picrylhydrazyl scavenging activity as compared to the control.

To maximize the economic benefits of Hyacinthus orientalis L., the micropropagation and morphogenesis induction of five Hyacinthus cultivars were investigated under four different concentrations of indole acetic acid (IAA) with two cytokinins, benzyl adenine (BA), or kinetin (Kin). Days for morphogenesis initiation and shoot formation in the red cultivars were fewer than in the blue and white cultivars. Blue cultivars showed an increase in fresh weight and chlorophyll content under either BA or Kin, but they showed an increase in shoot height in the BA treatments only. IAA at 1.5 mg/L caused a time reduction in days for morphogenesis induction and shoot formation and enhanced shoot height and fresh weight. Kin had a lesser impact than BA on all parameters at all concentrations. The number of shoots differed significantly among the cultivars. The Murashige and Skoog (MS) medium supplemented with 3.0 mg/L indole-3-butyric acid (IBA) produced the highest percentage of root formation (93.3%), number of roots/plantlet (5.26), and root length (1.10 cm). The Jan Bos cultivar at 3.0 mg/L IBA had the highest mean rooting percentage (100%) and number of roots per plantlet (6.66), while Pink Pearl had the highest root length (1.39 cm).

Ocimum basilicum L. sweet basil is native to India and Iran, an aromatic herb and perennial belong to the Lamiaceae family. This study was done at the Genetic Engineering and Biotechnology Laboratory, Faculty of Agriculture, Damanhour University, Egypt from 2019 to 2020. Developing stress tolerant plants using in vitro selection is an effective method; therefore, the purpose of this study was to detect the best concentration of phytohormones to produce embryogenic callus of Ocimum basilicum L. and study the effect of poly ethylene glycol (PEG) on embryogenic callus of basil.Leaf specimens of basil were cultured on MS medium (Murashige and Skoog) with concentration of auxin and cytokinin. A1 (2, 4-D at 0.5 mg/l), A2 (2, 4-D at 1.0 mg/l) and A3 (2, 4-D and BAP at 1.0 mg/l and 0.2 mg/l). Embryogenic callus of basil was sub cultured under normal and drought stress media containing different concentration of polyethylene glycol (PEG; M.W 4000) at 2, 5 and 10%. Results showed that medium A3 was the best medium of embryogenic callus induction. Also, the concentration of PEG at 5% was shown maximized callus survivability compared with the other PEG concentrations with no significant effect. This study adds new information on the effect of 5% PEG which showed the highest (positive) survivability of callus. The morphogenic of calluses on 5% PEG were yellowish, friable while the morphogenic of calluses on 10% PEG turned into brown.