Abstract
The cut flower business has been growing rapidly worldwide, with a positive and significant impact on the economies of many countries. Maintaining quality and extending the vase life of cut flowers are crucial aspects of the floral industry. Synthetic preservatives (silver nitrate, silver thiosulfate, nano-silver, hydroxy quinoline, thiabendazole, and aluminum compounds) have been commercially used in the vase to maintain the quality and longevity of cut flowers for a long time. However, these preservatives may persist in the environment, causing severe health hazards and environmental pollution, and are also expensive. Therefore, cut flower industries seek low-cost, eco-friendly, and safer alternatives. In this context, natural preservatives (NPs), including plant extracts (PEs) and essential oils (EOs), offer a promising and sustainable alternative to synthetic preservatives in the vase. This review highlights the potential NPs and their role in enhancing the quality and vase life of cut flowers. We discussed how these preservatives exert their beneficial effects, such as inhibiting microbial growth, reducing ethylene production, and enhancing water uptake, and also explored the potential issues associated with them. We conducted a structured literature review and summarized the most commonly used EOs and PEs, their optimal dosages, efficacy, and combinations, and concluded with future directions to enhance the vase life of cut flowers sustainably.
Introduction
Floriculture is an important enterprise in the world and significantly contributes to the economy of many countries. 1 The cut flower business holds a substantial position in the global floriculture sector, and it has experienced significant growth in both national and international markets. Globally, more than 145 countries are involved in the floriculture sector, with leading producers mostly from Western countries like the Netherlands, the United States, Colombia, and Italy. 2 In developing countries as well, farmers have shifted towards the commercial production of cut flowers, and the production of cut flowers has been steadily growing. Cut flowers are valued for beautification, social and cultural ceremonies, and expressing affection, emotion, and gratitude on various occasions, from the birth to death of people, including enhancing the beauty of homes, being used in social events such as weddings and funerals, as well as for welcoming and bidding farewell to individuals. 3
The vase life of cut flowers is one of the most critical factors that affect the consumer's preference during buying. 4 The postharvest longevity of cut flowers plays a crucial role in determining the overall value of the flower crop. 5 Prolonging the vase life and controlling the growth of harmful microorganisms in cut flowers presents a substantial challenge for researchers in the field of floriculture. 6 Both preharvest and postharvest factors can affect the postharvest life of cut flowers. 7 Growing environments and genotypes are the most critical preharvest factors that determine the longevity of a cut flower inflorescence in a vase.8,9 Similarly, the harvesting time, the stage of development, and postharvest handling equally play a significant role in the vase life of cut flowers. 10 The postharvest loss of cut flowers ranges from 20% to 40% due to improper postharvest handling, 5 which reduces about 30% to 40% of the farm value. 11 Most of the cut flowers are highly perishable due to high respiration rates and are extremely sensitive to storage conditions. Thus, it is important to reduce the postharvest loss and increase the postharvest life.12,13
Ensuring the quality of cut flowers from harvest to vase is a significant challenge for supply chains worldwide. 14 Different types of floral preservatives have been used by value chain actors (growers, wholesalers, retailers, and consumers) at different levels. Chemical preservatives (silver thiosulfate, silver nitrate, aluminum sulfate, hydroxy quinoline sulfate, hydrogen gas, thiabendazole, and aluminum compounds) have been widely used to reduce the loss and increase the vase life of cut flowers.15–21 However, the use of natural preservatives (NPs) (essential oils (EOs) and plant extracts (PEs)) has yet to be commercially exploited in the floriculture industry. The reliance on synthetic preservatives raises concerns due to their long-term environmental and health effects, making them potentially unsustainable.3,10 Additionally, the European Union's initiative to reduce chemical usage by 50% by 2030 could influence the global use of synthetic chemicals. 22 In this context, NPs offer promising and sustainable options for extending the vase life of cut flowers. Application of NPs has multiple practical implications, including reduced chemical residues in environment, suitability with eco-labeling and export standards, improved worker and consumer safety, while maintaining postharvest quality under commercial handling conditions. 23
Some synthetic chemical preservatives, like silver thiosulfate, contain heavy metals that pose risks of environmental pollution and health hazards. 24 Due to the persistence of these metals in soil and groundwater, as well as their potential migration into drinking water systems, many countries have already banned the use of silver thiosulfate.24,25 Consequently, growers and consumers seek cost-effective and environmentally sustainable alternatives, such as NPs.6,10 NPs such as EOs, PEs, plant juice, and plant sap offer antioxidative, antimicrobial, and bioregulatory properties that could benefit the cut flower industry.6,21,26,27 Studies have shown that adding EOs and PEs to the vase solution can significantly extend the vase life of cut flowers by several days, in some cases even doubling their expected lifespan, depending on the flower type and the nature and concentration of the extract used.6,27,28 Therefore, due to their antimicrobial properties and eco-friendly nature, exploring the use of NPs as a substitute for synthetic chemicals is necessary and promising.28,29
Despite increasing interest in NPs, existing studies on cut flowers remain scattered across species, preservative types, and mechanisms, with no comprehensive synthesis to guide researchers or the floriculture industry. Therefore, this review aims to evaluate and synthesize the current knowledge on the application of NPs in extending the vase life of cut flowers, with an emphasis on potential EOs and PEs for the cut flower industry and their mechanisms of action, comparative effectiveness, synergistic combinations, and practical applicability. Identifying trends, knowledge gaps, and promising natural compounds opens avenues for future research, provides insights to researchers, florists, and industry professionals, and promotes the adoption of sustainable postharvest practices in floriculture. Accordingly, we have structured this review around the following questions: (i) Which and what concentrations of NPs are most effective for major cut-flower species? (ii) What underlying mechanisms, such as antimicrobial action, membrane stabilization, oxidative stress reduction, or enhanced water uptake, explain their efficacy? (iii) What are the limiting factors of NPs for commercial application?
Review methodology
A structured literature review was conducted to summarize existing information on the use of NPs for extending the vase life of cut flowers. Relevant publications were extracted through searches in Web of Science, Scopus, PubMed, and Google Scholar, covering the period from 2000 to 2025. Peer-reviewed articles on application of PEs, EOs, organic acids, or other biological agents to extend the vase life of cut flowers were included in this study. We screened titles, abstracts, and full texts, and key information on species, treatments, and outcomes to support the synthesis, and identified research gaps as well.
Challenges encountered by cut flowers in a vase
Cut flowers encounter significant challenges affecting their shelf life in a vase. One major issue is the growth and proliferation of harmful microorganisms at the basal stem end, leading to vascular plugging. Due to this blockage, water uptake and retention are significantly reduced. 30 Microorganisms can rapidly colonize the cut ends of flower stems, leading to the blockage of xylem vessels, the disruption in water uptake, and early wilting.31,32 Bacterial growth is the primary reason for xylem vessel blockage, which reduces the hydraulic conductivity of water, produces ethylene endogenously and toxic secondary metabolites, and fosters cell wall degradation.33–36 Water stress resulting from limited water availability further reduces the vase life of cut flowers.30,37 Additional factors, such as physiological wound healing and air embolism, also contribute to xylem occlusion. 30 The vase life and quality of cut flowers are affected by the water relations and oxidative stress response. 28 After harvesting, cut flowers undergo oxidative stress,38,39 resulting in the production of reactive oxygen species (ROS), membrane degradation, accelerated senescence, and ultimately, cell death. 40 The ROS act upon nucleic acids, cellular proteins, and membrane lipids, which leads to oxidative damage.41,42 Hence, preventing the xylem blockage by microorganisms and oxidative injuries plays a crucial role in delaying senescence, maintaining floral quality, extending the longevity of flowers in a vase, and ensuring their high quality.6,10,28,43
Use of floral preservatives
The vase life of cut flowers varies significantly among different flower species, varieties, growing environments, preharvest management practices, harvesting methods, and postharvest handling techniques, including the use of preservatives. Among these factors, the choice and application of floral preservatives play a crucial role in maintaining flower quality and extending the vase life. These preservatives are diverse solutions derived from a mixture of sugar, salts, acids, biocides or germicides, and growth regulators. 3 Typically, the vase life of cut flowers is preserved by using solutions with sugars for energy and disinfectants to prevent microbial growth. 44 Sucrose is a primary component of the vase solution, which is generally enriched with different biocides or germicides, ethylene inhibitors, and organic acids.7,45 Floral preservatives reduce transpiration and senescence, inhibit ethylene production, enhance water uptake, improve the petal color, promote bud and flower opening, and prevent bacterial growth.3,46 Generally, cut flowers are treated with three types of preservative solutions, a bud-opening solution, a pulsing solution, and a holding solution, all of which help prolong the vase life. Synthetic biocides or germicides are typically used in preservative solutions to inhibit the growth of harmful microorganisms and prolong the vase life of cut flowers.47,48
Vase water chemistry plays a critical role in determining the performance of NPs. Electrical conductivity and pH of the vase solution influence water uptake, physiological responses of cut flowers, and the solubility, dispersion, and stability of NPs in the vase. 49 An acidic vase solution improves water uptake and suppresses microbial proliferation, whereas alkaline or hard water can reduce preservative efficacy by promoting the formation of mineral deposits in xylem vessels.50–53 Most EOs are hydrophobic in nature, their performance depends on the vase matrix. Generally, neutral to low pH and low hardness enhance dispersion and stability in water-in-oil emulsions, whereas hard water and high organic loads hinder solubilization, resulting in phase separation and reduced bioactivity. 54 However, the influence of vase water chemistry on EOs performance in cut flowers is poorly understood.
Among different preservatives, silver nitrate and silver thiosulfate are the most widely used synthetic germicides. However, silver is a toxic metal with harmful effects on microorganisms, plants, animals, and the ecosystem as a whole. 55 The organelles and cellular structure of organisms are disrupted by silver species through unfavorable binding interactions. 56 Silver ions and silver nanoparticles (SNPs) have cytotoxic effects and increase the production of ROS, which interfere with the DNA, lipids, proteins, and antioxidant defense system. 57 Additionally, these silver-based preservatives are costly, pose risks to human health and the environment, and can cause flower toxicity.10,26,58 As flowers are not a commodity used for consumption, many regulatory concerns regarding the use of synthetic preservatives remain undefined. However, the increasing popularity of edible flowers in culinary applications underscores the need for safer alternatives. 59 It is therefore imperative to replace synthetic chemicals and substances with natural and organic substances, especially EOs and PEs, as an eco-friendly, economical, and sustainable approach.
Studies indicate that natural products can be equally as effective as synthetic substances in maintaining vase life. For instance, Solgi et al. 47 reported that the vase life of gerbera flowers treated with 2 mg L−1 of SNPs (15.8 days) was statistically comparable to those treated with 100 mg L−1 of natural compounds such as carvacrol (15.9 days), thymol (14.4 days), zataria oil (14.0 days), and thyme oil (14.7 days). Similarly, Marandi et al. 60 found that ajowan oil at 500 mg L−1 (20 days) had a comparable effect to silver thiosulfate (150 mg L−1) (19 days) on the vase life of gladiolus flowers.
Ethylene production is one of the major factors limiting the longevity and quality of cut flowers, accelerating floral senescence and petal abscission. To avoid this, 1-methylcyclopropene (1-MCP), a synthetic plant growth regulator, has been widely used as an ethylene action inhibitor. It suppresses ethylene receptor genes while enhancing antioxidant activity.61,62 Compared to synthetic preservatives, 1-MCP is considered environmentally safer, though its effectiveness varies depending upon factors such as the flower genotype, formulation and concentration, treatment duration, maturity stage, and ethylene sensitivity.62,63 Additionally, the efficacy of 1-MCP diminishes at low temperatures.62,64
Alcohols (particularly ethanol and methanol) have also been used as floral preservatives. Studies have suggested that an ethanol treatment inhibits ethylene production and delays programed cell death, thereby significantly extending the vase life of cut flowers.65,66 While alcohol treatment is also an eco-friendly alternative, its commercial application remains limited, as other preservatives have shown greater effectiveness. Alcohol at high concentrations may act as a desiccant, drawing moisture from plant tissues and leading to dehydration, wilting, and necrosis. 67 In addition, NPs have been found to outperform alcohol in extending the quality and vase life of cut flowers. 68 However, combining NPs with 1-MCP and ethanol may enhance their efficacy while minimizing environmental and health hazards. 69
Preparation and potential roles of NPs
The methods of extraction of EOs and PEs may vary depending on the location of the presence of volatile oils and bioactive compounds in the plant and their proposed use. EOs are often extracted using the hydro-distillation method.6,70 In contrast, PEs are prepared by crushing plant components in a minimal volume of a solvent, such as water, followed by centrifugation to obtain a supernatant solution. This solution is then diluted with distilled water to create various concentrations of PEs.26,28 Steam distillation (azeotropic distillation), enfleurage, extraction with organic solvent in a continuous and discontinuous way, pressing or supercritical CO2 extraction are the most common methods for EOs extraction. 71 While the methods for PEs extraction are relatively simple, the proposed methods are direct, aqueous, and juice extraction. 72 However, analysis of bioactive compounds present in the PEs involves common phytochemical screening assays to different chromatographic and nonchromatographic techniques. 73 Using natural and active compounds such as herbal extracts and EOs is an alternative approach that has been considered for controlling fungal and bacterial infections and reducing the postharvest loss of horticultural crops and products, including flowers.74,75 Several studies have shown that EOs and PEs could be a promising and sustainable strategy to replace synthetic preservatives in the vase. PEs of neem, cinnamon, rosemary, and Aloe vera gel, as well as EOs of thyme, lemon grass, clove, eucalyptus, and peppermint, and many other spices have already been used as cut flower preservatives with greater efficacy. NPs are diverse, and their application in an optimum concentration can enhance the vase life and postharvest characteristics of cut flowers (Table 1).
List of commonly used natural preservatives and their optimal concentrations for prolonging vase life in different cut flower species.
EO: Essential Oil.
EOs have been shown to increase the vase life by maintaining the fresh weight, increasing the water uptake, and preserving the cell membrane integrity, which delays senescence and enhances the vase life.6,80 These oils also reduce water loss and transpiration while increasing the water uptake, thereby prolonging the vase life. 92 Similarly, PEs exhibit strong antimicrobial properties, preventing microbial growth, delaying bent neck, and reducing ethylene production, all of which contribute to the prolonged freshness of leaves and petals. 83 The application of EOs and PEs markedly increases the petal expansion, relative water content (RWC), chlorophyll content in the cut flower leaves, and carbohydrate content. 6 The treatment of cut flowers with EOs and PEs significantly improved the physiological and structural attributes of cut flowers, including the diameter of the flower head and stem, dry matter of flowers, total vase solution uptake, relative fresh weight, pigment content (chlorophyll a, chlorophyll b, carotenoid, and anthocyanin), sugar content, membrane stability index (MSI), water loss, stem bending, petal abscission, wilting percentage, and bacterial counts, thereby increasing postharvest longevity.27,28,70,77,79
Some studies on botanical preservatives have shown their potential as excellent preservatives. For instance, thyme EO significantly increased petal expansion (13.10%), showing the lowest reduction in the MSI value (7% decrease in membrane integrity), the highest chlorophyll content (79.63 SPAD), higher RWC levels, the highest carbohydrate content (14.5%), the highest phenol content (21.68 mg g−1 GAE), and a reduction in malondialdehyde (MDA) and hydrogen peroxide (H2O2) levels in cut carnations. 6 Similarly, in chrysanthemums, thyme EO (500 mg L−1) extended the vase life to 36.50 and 33.40 days in two consecutive seasons, while clove EO (250 mg L−1) prolonged the vase life to 35.88 and 31.33 days. In contrast, untreated control flowers lasted only 18 and 17 days, respectively. 27 Salmi et al. 77 also reported that the vase life of cut roses was almost double when treated with 200 μL L−1 (11.2 days) of EO of mentha as compared to an untreated control (6.70 days). However, the effectiveness of botanical preservatives varies depending on the type and concentration used, as shown in Table 2. Further research is necessary to optimize formulations for different flower species and postharvest conditions.
Comparison of relative vase life of different cut flowers treated with different essential oils and plant extracts versus untreated control.
EO: essential oil; PE: plant extract.
Preservative action of NPs
Plant extracts
PEs (leaf extract, fruit extract, and peel extract) have been extensively used to improve the postharvest longevity and quality of cut flowers. PEs contain bioactive secondary metabolites, such as flavonoids, steroids, and terpenoids, which possess antimicrobial, antioxidant, and insecticidal properties. 137 Studies have shown that vegetables, fruits, herbs, and spices are rich in a variety of antioxidant compounds such as carotenoids, retinoids, tocopherols, ascorbic acid, phenolics, flavonoids, and polyphenols along with essential nutrients, vitamins, and phytohormones (Table 3).47,121,147 PEs can induce an antioxidant defense system in plants due to the presence of antioxidants, osmoprotectants, and phytohormones. 148 They can alter gene expression and induce anatomical modifications that help improve flower longevity. 26 Additionally, these PEs affect physiological and biochemical processes, protecting plants from oxidative damage by stimulating the production of antioxidative enzymes. 149
Bioactive phytochemical constituents of major essential oils and plant extracts.
EO: essential oil.
One of the key benefits of PEs is their biocidal properties, which can control the diverse range of microbial populations in vase solutions, thereby extending the vase life of cut flowers. 150 PEs improve key physiological and biochemical biomarkers. Treating cut flowers with PEs increases total phenolic and antioxidant enzyme activities, suppresses MDA and H2O2 production, maintains the membrane integrity, and could serve as a novel preservative in the cut flower industry.116,121 Phenols are known for their non-enzymatic antioxidative properties, which may lead to decreased levels of MDA and H2O2. 151 Applying PEs has been shown to extend the longevity of flowers in the vase by increasing the MSI and enhancing the activity of antioxidant enzymes, such as catalase (CAT) and peroxidase (POD). 66 The postharvest treatment with PEs increases proline levels in cut flowers, indicating a reduction in the water stress and scavenging of oxidative stress. 26 Treating cut flowers with PEs maintains water relations and induces stomatal closure, which reduces the water loss, delays senescence, and ultimately prolongs the vase life. 26 Furthermore, using PEs enhances levels of total soluble proteins, sugars, and phenols in the florets of cut flowers, contributing to an extension of their vase life.6,116
Essential oils
EOs are emerging as a novel and eco-friendly approach with diverse agricultural and industrial applications. The EOs extracted from various aromatic plants, spices, and herbs offer a wide array of phytochemicals known for their remarkable antimicrobial and antioxidative characteristics.152–154 EOs are natural compounds primarily derived from plants belonging to families such as Apiaceae, Asteraceae, Lamiaceae, Myrtaceae, Lauraceae, Poaceae, and Rutaceae.155,156 While EOs have been widely used to control postharvest pathogens of fruits and vegetables, their use as preservatives in the cut flower industry remains limited. However, EOs hold great potential as a natural and eco-friendly approach to improve the vase life of cut flowers. 157
EOs contain sulfur-containing and oxygenated compounds, like alcohols, terpenes, phenols, and their derivatives, which are valued for astounding antimicrobial properties (Table 3).158–160 The antimicrobial properties of EOs increase the uptake of the solution62,79 and may also inhibit ethylene production, thereby delaying floral senescence and extending the longevity of cut flowers. 79
EOs have been reported to increase the petal flower diameter and petal reflection in cut flowers.27,96 The antioxidative properties of EOs possess chlorophyllase activity, preventing chlorophyll breakdown. 161 This results in sustained glucose synthesis and cellular activity, 162 ultimately preserving the chlorophyll content of the cut flowers. 163 Studies have demonstrated that the total carbohydrate content (primarily glucose) is increased with the increase in the chlorophyll content, which helps maintain the osmotic balance and effective respiration.6,110
Water stress and vascular blockage lead to an increase in free radicals within chloroplasts. 27 The presence of free oxygen radicals, such as H2O2, results in lipid peroxidation, leading to elevated MDA production.27,164 The accumulation of H2O2 and MDA serves as an indication of cellular membrane degradation. The application of EOs has been shown to significantly reduce H2O2 levels in the leaves of cut flowers. 6 EOs derived from plant herbs contain high levels of phenolic compounds that possess the ability to decrease membrane lipid oxidation and MDA levels and eliminate ROS. 165 High MSI and low MDA levels are indicative of an extended vase life for cut flowers. 166 The level of critical biomarkers such as MDA, H2O2, and total antioxidant activity (DPPH radical-scavenging activity) decreased with the application of NPs in the vase. 167
Furthermore, EOs have been found to enhance the total phenol content in the leaves of cut flowers, which is essential for counteracting oxidative damage. 6 One of the primary causes of premature petal ageing is the release of free oxygen species during hydrogen peroxide decomposition. Phenols act as antioxidants that counteract the detrimental effects of oxygen released during hydrogen peroxide breakdown, thereby slowing down the ageing process of petals.168,169
Mechanism action of NPs against pathogens
NPs have significantly reduced the bacterial populations in the vase solutions, as reported by various studies.10,28,70,115,116,121 EOs and PEs possess an antibacterial activity against both Gram-positive and Gram-negative bacteria.105,170 The active components of EOs and PEs are also capable of penetrating the cell wall and cytoplasmic membranes of fungi, leading to structural disruption and microbial death.170,171
Although the mechanism by which EOs and PEs, and their active ingredients, impede pathogens is not fully understood, it is hypothesized that their lipophilic compounds disrupt cell membranes, causing the loss of structural integrity. The low-molecular-weight, highly lipophilic compounds found in EOs and PEs can easily pass through cell membranes to elicit biological responses. 63 In general, EOs and PEs inhibited the pathogen's growth by various mechanisms, such as disrupting the membrane structure and function (including the efflux system), interrupting DNA/RNA synthesis and function, interfering with the intermediary metabolism, and inducing the coagulation of cytoplasmic constituents.172–174
Some EOs and their derivatives exhibit antimicrobial properties as a result of their hydrophobic nature, allowing them to interact with the lipids present in the bacterial cell wall, cell membrane, and mitochondria. This interaction increases the membrane permeability, leading to ion leakage, cellular dysfunction, and ultimately cell death. 175 Additionally, EOs disrupt bacterial respiratory chains, further contributing to their antimicrobial efficacy. 47 Evidence suggests that a number of these antimicrobials act on the cytoplasmic membrane, disrupting its structure and function, leading to membrane swelling and increased permeability. The loss of the selective permeability of the cytoplasmic membrane is commonly cited as the primary cause of cell death. 176 The hydrophobic nature of PEs allows them to integrate into the lipid layers of the cell membrane and mitochondria, making them more permeable and ultimately leading to the leakage of cell contents from bacterial cells. 177
Some other EOs, such as carvacrol, alter the structure of bacterial cell membranes by modifying fatty acids, leading to changes in fluidity and permeability, as well as depleting the adenosine triphosphate (ATP) of bacterial cells.6,159,178 Carvacrol can also inhibit the production of the protein flagellin, which is crucial for bacterial mortality. 178 Methyl carvacrol, thymol, citronellol, and menthol induce cell membrane expansion and facilitate passive ion transport across phospholipids 179 or inhibit toxin release and reduce bacterial virulence. 180 Similarly, eugenol demonstrates its antimicrobial properties by modifying the outer fatty acid layer of bacterial cell membranes. Additionally, it can target key bacterial enzymes such as amylase, histidine, proteases, ATPase, and carboxylase. 181 In addition to those EOs, citronellal has been shown to alter hydrophobicity and disrupt membrane integrity, allowing the efflux of K+ ions. 182
In cut flowers, bacterial biofilm formation at the stem-cut surface occludes xylem vessels and restricts subsequent water uptake, thereby accelerating wilting and senescence. 183 NPs disrupt early biofilm establishment at the cut end by inhibiting microbial adhesion, suppressing quorum-sensing (QS) pathways, degrading extracellular polymeric substance production, and disrupting membrane integrity, thus maintaining xylem conductivity. 184 At the cellular level, different classes of natural compounds target distinct microbial structures and functions. However, disruption of biomembranes is the most frequently reported mechanism. Phenolic isomers like thymol and carvacrol perturb the lipid fraction of bacterial membranes, leading to bacterial lysis due to alterations of membrane permeability and leakage of intracellular contents.185,186 The other proposed mechanisms include inhibition of efflux pumps, prevention of the formation of biofilms, and inhibition of cell division, motility, membrane porins, and membrane ATPases.186,187
Limitations of NPs
Considerable work has been carried out to test the efficacy of NPs for the postharvest management of fruits and vegetables around the globe. The industrial application of plant-based products has also been gaining momentum for the postharvest management of fruits and vegetables. However, their use in the cut flower industry remains relatively unexplored, necessitating further research to enable large-scale applications. While NPs have several theoretically desirable attributes over synthetic chemicals, they also come with challenges that must be addressed before their widespread adoption.
The efficacy of NPs greatly depends on the quality of the raw material used, the availability of the raw material, the presence of active ingredients, product standardization, and the integration of multiple NPs for enhanced efficacy. 188 Additionally, their practical application is hindered by a limited range of effectiveness, lack of consistency, poor solubility in water, rapid degradation, lack of formulations, oxidation susceptibility, and diverse extraction methods.189–191 This variability is further influenced by chemotype, plant part, geographic origin, harvest stage, and extraction method, leading to batch-to-batch variability in bioactive composition.192,193 Such inconsistency complicates reproducibility and may limit standardization for commercial use in cut flowers. Environmental factors such as light, temperature, and oxygen availability are also recognized to have a crucial impact on NPs, particularly EOs stability and integrity. 194
Moreover, the potential phytotoxicity of certain phytochemicals is a concern. NPs may cause phytotoxicity, leading to visible damage, leaf abscission, or premature senescence. 195 Studies have shown that roses treated with medium to high concentrations of EOs in an aqueous form exhibited greater phytotoxic damage compared to those exposed to low concentrations or vapor-based treatments. 60 EOs at high concentrations may impose a phytotoxic response to cut flowers and cause visible damage to leaves and their early abscission due to cell membrane injury. 196
Furthermore, regulatory issues remain a significant challenge to the commercial availability of novel NPs in the market. 188 In addition, synthetic, substandard, and adulterated products available on the market may also pose a serious challenge for NPs. For NPs to be widely adopted in the cut flower industry, it is, therefore, essential to investigate their mode of action and efficacy on various types of cut flowers. A deep understanding of these mechanisms would facilitate the development of optimized treatment plans that aim to extend the vase life of cut flowers.
Conclusions and future prospects
NPs offer a promising solution for improving the quality and longevity of cut flowers, primarily by inhibiting microbial growth and preventing the plugging of water vessels. They could serve as an effective and economically viable alternative to synthetic chemical substances in the cut flower industry. However, further research is necessary to understand and optimize their chemical properties, including the concentration, hydrophobicity, pH, composition, synergistic interaction, and functional groups. Future research should also focus on refining existing NPs and investigating their physiological, biochemical, and genomic effects on cut flowers. NPs should be standardized based on vase life (days), RWC, MSI, microbial load (CFUs at stem end or vase water), and ethylene production or sensitivity. Other important future strategies include encapsulation and use of co-formulants to increase the effectiveness of NPs. Additionally, exploring the use of ornamental cut foliage, known for beneficial NPs, could be a cost-effective strategy for enhancing the longevity of cut flowers in a vase without requiring separate extract formulations. Research should also aim to explore locally available plant species that have a potential preservative action. NPs must be optimized based on the characteristics of target microorganisms (type, genus, species, and strain). An emphasis should also be placed on validating their efficacy and safety, particularly in overcoming challenges, such as minimal residual activity, through improvements in formulation technology. Appropriate benefit-cost analysis could aid in the comparability, reproducibility, and relevance of using NPs in preserving cut flowers. Prioritizing the development and commercialization of NPs solutions will contribute to a healthy and eco-friendly floral industry. Furthermore, the potential of NPs in prolonging the shelf life of edible flowers presents an exciting path for research, as these applications could gain quicker acceptance within the industry.
Footnotes
Ethical considerations
Ethical approval and informed consent were not required for this review.
Author contributions
Nirajan Bhandari: conceptualization, review, writing original draft, and visualization; Umed Kumar Pun: conceptualization, writing-review and editing, supervision, and validation; Milan Panth: writing-review and editing, and validation. All authors have read and agreed to the published version of the manuscript.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Data availability
This review is based entirely on previously published studies and publicly available data. No new data were generated or analyzed in this study.