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Modern horticulture relies heavily on chemical inputs to ensure plant growth and health. While the benefits of plant-associated microbes in promoting drought tolerance are well established, their consistent performance under field-like conditions remains limited. We hypothesize that a minimal, drought-adapted bacterial community—composed of strains isolated from resilient plants—can not only outperform single-strain inoculants, but also confer drought tolerance across plant cultivars when transplanted into a sensitive host such as clove basil. To test this hypothesis, three drought-tolerant bacterial strains from the Pseudomonas fluorescence genus were selected and their effects on clove basil ( Ocimum gratissimum ) plants were evaluated under severe drought stress conditions. The protectiveness of bacteria and their efficacy increased by growing the bacterial consortium size from one to three strains. A minimal community of three bacterial strains increased clove basil growth, nutrient content, stress tolerance and essential oil constituents under drought conditions. We propose that the minimal bacterial community enhance drought resilience in clove basil by boosting nutrient uptake and increasing the production of key secondary metabolites such as linalool and caryophyllene. By leveraging the potential of a minimal bacterial community, this research presents a pathway toward enhancing vegetable drought tolerance, contributing to a more sustainable and resilient horticultural practice.

Considering the significance of fenugreek as a valuable medicinal and food plant, assessing the genetic diversity of different populations of this species is essential for optimizing performance and adaptability to environmental conditions. This study aims to investigate genetic diversity and identify important phenotypic traits in various Iranian fenugreek accessions (“Mashhad”, “Tehran”, “Yazd”, “Shiraz”, “Birjand”, “Isfahan”, “Kerman”, “Kalat”, “Neyshabur”), an experiment was conducted in a randomized complete block design with three replications and nine treatments (accessions) in Iran. The results showed that the highest seed yield was observed in “Kalat” (120.73 g/m 2 ) and the lowest seed yield was observed in “Neyshabur” (29.28 g/m 2 ) accessions. Also, “Isfahan” had the highest number of branches (10.8/plant), and the highest 1000-seed weight (29.6 g) was recorded in “Shiraz”. It was also found that the number of days to the appearance of the first flower and the arrival of the last pod was the least in the “Yazd” (50 and 85 days) and the highest in the “Kerman” (87.67 and 170 days), respectively. It was also found that the highest content of soluble sugar (0.32%) belonged to the “Mashhad” and the highest amount of total chlorophyll (2.36 mg/gfw) belonged to the “Isfahan” accessions. “Birjand” had the highest antioxidant activity (55.64%). The highest abundance of bluish spots was also seen in the “Kalat” accession. The results of this study showed a considerable diversity between the studied accessions. The most suitable accession for harvesting seeds was “Kalat” and the “Isfahan” accession was the most appropriate for harvesting herbal yield. The results of this study provide a valuable foundation for future research aimed at identifying specific genotypes with superior traits, such as higher yield or stress resistance. Future studies can build upon these findings by focusing on selecting and breeding elite fenugreek lines for use in crop improvement programs.

Salinity is an abiotic stress that negatively affects plant growth and the synthesis of secondary metabolites. This study aimed to evaluate the effects of foliar applications of titanium (Ti) and nano-titanium (nano-Ti) at concentrations of 0, 50, and 100 mg/L under salinity levels of 0, 50, and 100 mM NaCl in controlled greenhouse conditions. A factorial experiment based on a completely randomized design with four replications was conducted. A comprehensive set of morphological (plant height, fresh and dry biomass), physiological (photosynthetic pigments, soluble carbohydrates, proline, and protein content), and biochemical parameters (antioxidant enzyme activities including superoxide dismutase, guaiacol peroxidase, and ascorbate peroxidase), as well as essential oil (EO) content and composition, were assessed. Salinity stress markedly reduced plant growth, chlorophyll content, and EO yield, while increasing oxidative stress markers such as malondialdehyde (MDA) and hydrogen peroxide (H₂O₂). The application of 100 mg/L nano-titanium under non-stress conditions significantly increased plant height (47.01 cm), fresh weight (87.33 g), and essential oil yield (0.639 g/pot). Moreover, essential oil content reached a maximum of 1.84% under 50 mM salinity with 100 mg/L nano-titanium, representing a 212% increase compared to the control. Nano-titanium application under salinity stress increased APX and SOD activities by 176% and 237%, respectively, compared to the control. GC–MS analysis revealed linalool, trans-caryophyllene, 1,8-cineole, and germacrene D as the major EO constituents, whose concentrations were notably influenced by both salinity level and Ti treatments. These findings suggest that nano-Ti has the potential to be used as a sustainable biostimulant to enhance growth and secondary metabolite production in M.  ×  gracilis under saline environments.

Medicinal and aromatic plants have the ability to transmit volatile allelochemicals and affect their surrounding organisms. In this regard, their interaction should also be considered. The inhibitory effects of 112 essential oils on lettuce seed and seedling were investigated by cotton swab method. Germination (G%), Mean germination time (MGT), Lethal of embryo (L%), dormancy (D%), radicle growth (R%), and hypocotyl growth (H%) were measured. Two methods were used for evaluating allelopathic interaction effects: the simplified modified dilution check-board technique (SMCT) and the isobologram. Thymus daenensis had the highest inhibitory effect on G% (IC50 = 2.9 ppm) and the most lethal effect on the embryo (LC50 = 7.2 ppm). Thymus transcaspicus, Dracocephalum moldavica, Artemisia sieberi and Amomum subulatum had the greatest effect on MGT. Ziziphora tenuior, Trachyspermum ammi and Pelargonium graveolens had the highest effect on D%. Origanum vulgare was the strongest growth inhibitor. The highest synergistic effect on G% was in A. subulatum + Mentha suaveolens, on H% was related to Perovskia abrotanoides + T. daenensis, and on R% was observed in Artemisia vulgaris + M. suaveolens. The results of this study can lead to identification of new phytotoxic compounds in EOs and control weeds more effectively.

One of the major factors limiting the production of medicinal plants in arid and semi-arid areas is water deficit or drought stress. One-third of the land in the world is arid and semi-arid and is inhabited by nearly 4 × 108 people. Ocimum basilicum (sweet basil) is a valuable medicinal plant that is sensitive to water deficit, and water shortage negatively affects sweet basil yield and quality. Water availability in the root zone of basil could ameliorate the negative effects of water shortage. To the best of our knowledge, although the effects of hydrophilic polymers (HPs) have been studied in different agricultural crops, the effects of HP application in medicinal plants have not been previously investigated. This investigation was conducted to explore the effects on water use efficiency when using Stockosorb® (STS) and psyllium seed mucilage (PSM) as hydrophilic polymers (HPs) and the effects of these HPs on essential oil quality, quantity, and yield. The research was set up in a factorial experiment on the basis of completely randomized block design with three replications. We used two HPs, STS (industrial) and PSM (herbal), with two methods of application (mixed with soil, mixed with soil + root) at four concentrations (0%, 0.1%, 0.2%, and 0.3% (w/w)). Results showed that the STS and PSM significantly increased the dry herb yield (both shoot and root) in comparison to the control, and the improving effect was higher when these HPs were mixed with soil + root. The highest dry herb yield (6.74 and 3.68 g/plant for shoot and root, respectively) was detected in the PSM at 0.1% mixed with soil + root. There was not any significant difference in dry herb yield among PSM (0.1%), PSM (0.2%), and STS (0.2%) when mixed with soil + root. Soil application of PSM and soil + root application of STS at a concentration of 0.3% increased the Essential Oil (EO) content almost three-fold in comparison to the control (0.5% and 0.52% to 0.18% v/w, respectively). The maximum essential oil yield was recorded in plants treated with STS (0.2% in) or PSM (0.1%) by soil + root application (0.21 and 0.19 mL/plant, respectively). PSM at concentrations of 0.1% and 0.2% (mixed with soil + root) showed the highest water use efficiency (1.91 and 1.82 g dry weight (DW)/L H2O, respectively). STS mixed with soil also significantly improved water use efficiency (WUE) in comparison to the control. The application of these HPs improved the quality of sweet basil essential oil by increasing the linalool and decreasing the eugenol, epi-α-cadinol, and trans-α-bergamotene content.

Carbon nanomaterials such as single-walled carbon nanotubes (SWCNTs) offer a new possibility for phyto-nanotechnology and biotechnology to improve the quality and quantity of secondary metabolites in vitro . The current study aimed to determine the SWCNTs effects on Thyme (Thymus daenensis celak.) seed germination. The seedlings were further assessed in terms of morphological and phytochemical properties. Sterile seeds were cultured in vitro and treated with various concentrations of SWCNTs. Biochemical analyses were designed on seedling sample extracts for measuring antioxidant activities (AA), total flavonoids (TFC) and phenolic contents, and the main enzymes involved in oxidative reactions under experimental treatments. The results indicated that an increase in SWCNTs concentration can enhance the total percentage of seed germination. The improvement was observed in samples that received SWCNTs levels of up to 125 µg ml −1 , even though seedling height and biomass accumulation decreased. Seedling growth parameters in the control samples were higher than those of grown in SWCNT-fortified media. This may have happened because of more oxidative damage as well as a rise in POD and PPO activities in tissues. Additionally, secondary metabolites and relevant enzyme activities showed that maximum amounts of TPC, TFC, AA and the highest PAL enzyme activity were detected in samples exposed to 62.5 µg ml −1 SWCNTs. Our findings reveal that SWCNTs in a concentration-dependent manner has different effects on T. daenensis morphological and phytochemical properties. Microscopic images analysis revealed that SWCNTs pierce cell walls, enter the plant cells and agglomerate in the cellular cytoplasm and cell walls. The findings provide insights into the regulatory mechanisms of SWCNTs on T. daenensis growth, germination and secondary metabolites production.

Nanoelicitors are biological and non-biological factors that can affect the synthesis of secondary metabolites in medicinal plants. Feverfew is a valuable medicinal plant containing effective and important anti-cancer compounds (essential oil and parthenolide). This study was conducted to investigate the effects of zinc oxide nanoparticles (ZnONPs) on yield, metabolites content, and zinc and iron absorption of Feverfew. After seed preparation, seedling production, soil physicochemical properties analysis, ZnONPs treatments, maintenance and harvesting at full flowering stage, morphological traits and yield components were measured. The essential oil was extracted by Clevenger and parthenolide was identified by UPLC-MRM-MS. The content of Zn and Fe were measured by OES-ICP. The effects of ZnONPs were significant on all morpho-phytochemical traits. An increased biological yield (dry weight) was observed at 2000 ppm ZnONPs (32.54 g/day) compared to control (28.09 g/day). The highest (0.9% V/W) and lowest (0.56% V/W) content of essential oil were related to 1000 ppm ZnONPs and control. The content of parthenolide decreased at different levels of ZnONPs. The lowest (36.83 mg/kg DW) and highest (266.02 mg/kg DW) rates of Zn absorption were observed in control and 2000 ppm ZnONPs. Nanoparticles at all concentrations increased the biological yield, essential oil content, and Zn absorption. None of the ZnONPs concentrations improved the flower yield. Along with increasing ZnONPs and Zn uptake, parthenolide levels decreased. Also, it was determined that there was an antagonistic effect between Zn and Fe absorption.

Grafting is a technique commonly used in horticulture to minimize damage from soil-borne diseases and bolster plants’ ability to withstand stress, ultimately resulting in increased plant productivity. Cucurbit plants are frequently grafted for these purposes, and their seeds are widely used as nuts, food additives, and for medicinal properties worldwide. However, no information is available on the impact of grafting on the seed and oil yield and properties of medicinal pumpkins. This study is the first to investigate the effect of grafting on medicinal pumpkin ( Cucurbita pepo var. styriaca) seeds’ yield and oil properties. Commercial medicinal pumpkins were grafted onto five different rootstocks ( C . pepo hybrids) including: ‘code 11’, ‘code 36’, ‘code 45’, ‘code 42’ and ‘code 21’) using three different grafting methods (Side grafting, Hole insertion grafting and cleft grafting). The results showed that the type of rootstock and grafting method significantly affected fruit yield, seed yield, oil yield, and oil qualities. The research revealed that there were no issues with graft incompatibility between the rootstock and medicinal pumpkins. Side-grafting was identified as the most successful method, and these plants were utilized in farm experiments. Furthermore, the rootstocks had a notably positive impact on the success rate, with code 42, code 45, and code 21 rootstocks demonstrating the highest percentage of successful grafts. Medicinal pumpkin ( Cucurbita pepo var styriaca ) plants grafted through the side grafting technique on code 45 hybrids have demonstrated the highest yield and optimal oil properties. Thus, these grafted plants are highly recommended for the commercial production of medicinal pumpkins.

Safranal, the main volatile chemical of Saffron (Crocus sativus) was studied to estimate its allelopathic effects on the photosynthetic pigment chlorophyll, leaf electrolyte leakage, fresh weight, catalase (CAT), and peroxidase (POX) activity of the test plant Lettuce (Lactuca sativa). In this study, the effective concentration (EC50) of safranal on CAT was estimated to be 6.12 µg/cm3. CAT activity was inhibited in a dose-dependent manner by the increase in the safranal concentration while POX activity was increased. Moreover, Safranal caused significant physiological changes in chlorophyll content, leaf electrolyte leakage, and fresh weight of several weed species with Lolium multiflorum being the most sensitive. Furthermore, 5 µM Safranal showed significant inhibitory activity against dicotyledonous in comparison to the monocotyledons under greenhouse conditions. The inhibition of the CAT by safranal was similar to those of uncompetitive inhibitors, and therefore the decline in carbon fixation by plants might be the mechanism behind the inhibitory activity of safranal.

In this study the sensitivity of peach tree (Prunus persica L.) to three water stress levels from mid-pit hardening until harvest was assessed. Seasonal patterns of shoot and fruit growth, gas exchange (leaf photosynthesis, stomatal conductance and transpiration) as well as carbon (C) storage/mobilization were evaluated in relation to plant water status. A simple C balance model was also developed to investigate sink-source relationship in relation to plant water status at the tree level. The C source was estimated through the leaf area dynamics and leaf photosynthesis rate along the season. The C sink was estimated for maintenance respiration and growth of shoots and fruits. Water stress significantly reduced gas exchange, and fruit, and shoot growth, but increased fruit dry matter concentration. Growth was more affected by water deficit than photosynthesis, and shoot growth was more sensitive to water deficit than fruit growth. Reduction of shoot growth was associated with a decrease of shoot elongation, emergence, and high shoot mortality. Water scarcity affected tree C assimilation due to two interacting factors: (i) reduction in leaf photosynthesis (-23% and -50% under moderate (MS) and severe (SS) water stress compared to low (LS) stress during growth season) and (ii) reduction in total leaf area (-57% and -79% under MS and SS compared to LS at harvest). Our field data analysis suggested a Ψstem threshold of -1.5 MPa below which daily net C gain became negative, i.e. C assimilation became lower than C needed for respiration and growth. Negative C balance under MS and SS associated with decline of trunk carbohydrate reserves--may have led to drought-induced vegetative mortality.