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Borage leaf extract improves the vase life of cut gladiolus flowers by delaying the senescence process and reducing water stress
Abstract
The quality of cut flowers is always associated with the vase life of the consumer. In previous studies, novel preservative postharvest treatments have been tested to prolong vase life and commercial quality. This work aimed to study the potential use of borage (Borago officinalis L.) leaf extract as a natural vase life enhancer for cut gladiolus flowers. Borage leaf extracts (BE) applied as 1 %, 2 %, 3 %, and 4 % (v/v) in vase solutions extended the vase life from 6.2 to 13 d. We recorded a concentration of BE at 3 % significantly improved the number of open flowers, the floret diameter, the relative fresh weight, chlorophyll, and carotenoid content. BE showed antioxidant properties, as they decreased oxidative stress and reduced lipid peroxidation as demonstrated by the malondialdehyde (MDA), hydrogen peroxide (H 2 O 2) concentrations, and membrane stability index (MSI). Post-harvest treatment with BE boosted proline content in cut gladiolus, indicating a reaction that was associated with the alleviation of water stress. BE application improved total soluble proteins, sugars, and phenols in the florets resulting in a prolong of the vase life. Bacterial count was reduced in BE-treated vase solutions depicting less proliferation of bacteria at stem ends and hence reduced stem blockage. The best postharvest performance was obtained by the BE at 3 %. The promising results of current experiments may be suggested as a potential post-harvest treatment to prolong the vase life of sword lily.
Gladiolus (Gladiolus grandiflorus Andrews) is a high-valued bulbous cut flower. However, the shorter postharvest life of the gladiolus, limits its marketing and commercial value. In the present investigation, the effect of lemon grass (LG) essential oil as an antimicrobial agent was studied towards increasing the vase life of gladiolus. The results revealed that as compared to control (distilled water), treatment with a lower concentration of 5 µL L⁻¹ LG essential oil prolonged the vase life of gladiolus up to 11 days (d). Scanning Electron Microscope (SEM) observation indicated that the sample treated with 5 µL L⁻¹ LG essential oil showed intact vasculature, suggesting reduced microbial blockage at the stem end which was further corroborated by microbial count. Biochemical analysis suggested an increased level of total soluble sugars, carotenoid content, lower MDA accumulation, and higher activity of antioxidant enzymes in LG treated flowers. Moreover, transcripts levels of genes associated with senescence viz., GgCyP1 and GgERS1a were downregulated, while expression of GDAD1 and antioxidant genes such as GgP5C5, GgPOD 1, GgMnSOD, and GgCAT1 were upregulated in LG treated cut spikes as compared to control. Among various treatments we have concluded that, the vase life of the gladiolus cut spike was improved along with the relative fresh flower weight and diameter of flower at the lower dose of 5 µL L⁻¹ LG oil in the vase solution. Thus, LG oil as an eco-friendly agent has the potential to extend the postharvest life of cut flowers.
Background
Cut flower longevity is often limited by adverse water relations or oxidative stress. The potential of single- and multi-walled carbon nanotubes (SWCNTs and MWCNTs, respectively) on prolonging vase life was addressed. Dose–response curves were obtained by applying five concentrations (0–80 mg L ⁻¹ ) of SWCNTs or MWCNTs either once as a foliar spray or continuously in the holding solution of three carnation cultivars. Next, the optimal concentration of either SWCNTs or MWCNTs was employed to evaluate several parameters critical for vase life.
Results
Foliar spray application exerted minor effects on water relations, flower opening and keeping quality. By contrast, including CNTs in the holding solution sustained a positive water balance for a longer period, improved flower opening and prolonged vase life. These effects were similar between SWCNTs and MWCNTs, and were concentration-dependent. The optimal concentration for vase life was higher for MWCNTs as compared to SWCNTs, and for two cultivars as compared to the third one. At optimal concentration, SWCNTs or MWCNTs in the holding solution generally maintained turgidity, and alleviated chlorophyll degradation, electrolyte leakage and lipid peroxidation. These effects were related to increased activation of enzymatic (ascorbate peroxidase, catalase, peroxidase and superoxide dismutase) and non-enzymatic (carotenoids, polyphenols, and flavonoids) antioxidants.
Conclusion
CNTs in the holding solution were very effective in stimulating vase life through improved water relations and enhanced antioxidant machinery stimulation.
Graphical Abstract
The efficacy of plant-based biostimulants lays on the extraction of bioactive compounds that can trigger positive biological responses in plants. Their use has been increasing for lowering the production costs, enhance the yield and the stress tolerance, and improve the cropping systems’ sustainability. The aim of this work was to investigate the effect of maceration time on borage extracts, subsequently sprayed on rocket plants hydroponically grown. A preliminary test was also assessed to evaluate the extracts’ effect on seeds germination. Borage leaves and flowers were separated and macerated in the same conditions for different times. The obtained borage extracts were applied two times during the cultivation of rocket plants. The yield was not affected by the treatments, while the quality of leafy vegetables was improved. The results indicated that the flower extracts (FE) were more active than leaf extracts (LE) in stimulating the crop response. Promising results were observed on the nitrate assimilation, with reduced accumulation in the edible and commercial parts. Non-destructive analysis revealed that electron transport rates were significantly higher in treated plants. Biostimulant effects were also confirmed by the lowering of sucrose and sugars content in the treated plants and by a general increment of secondary metabolites.
Cut flowers have become an export income in the global floriculture market. They have multiple uses, such as for home beautification, in ceremonies (including weddings and funerals), and as symbols of love, appreciation, respect, etc., in humane society. Each type of cut flower has a different vase life and the longevity of their freshness is linked to preharvest, harvest, and post-harvest tools and conditions. The postharvest quality and vase life must be considered in order to obtain the desirable qualities of cut flowers, and factors that affect this are important in the floral industry. The use of floral preservative solutions is good practice for prolonging the vase life of cut flowers. Currently, the eco-friendly solutions, which are used as floral preservatives for extending cut flower vase life, have been discovered to be a low-cost and organic alternative as compared to chemical solutions. However, there are certain problems associated with the use of chemical and eco-friendly solutions. In this review, we summarize several potential approaches to improve flower vase life and discuss the best choices for holding-preservative-solution practices.
Gladiolus is in demand worldwide as a cut-flower or landscaping plant, because of its superior commercial and ornamental value. Application of plant-based biostimulants has gained interest in the horticulture industry as an innovative and promising approach to ensure enhanced and sustainable yields along with better product quality. The influence of pre-plant corm soaks supplemented to 5% (v/v) with an aqueous extract from Moringa oleifera leaves (MLE) either alone or in combination with 50 mg/L salicylic acid (SA) or 50 mg/L gibberellic acid (GA) on the vegetative, physiological, and ornamental characteristics of potted gladiolus (Gladiolus grandiflorus) was investigated. In general, the treatment order for greatest horticultural value for all the parameters examined was: MLE + SA + GA > MLE + GA or SA individually > MLE alone > water-only control. Compared to other treatments, corms soaked in MLE + SA + GA had the earliest sprout time (3.7 days earlier than control), shortest production time (11 days earlier than control), tallest plant (159.5 cm), greatest number of leaves per plant (8.85 leaves), greatest maximum leaf area (66 cm 2), highest SPAD reading (112) and photosynthetic activity (6.7 mmol m −2 s −1), longest spike length (91 cm), greatest number of florets per spike (20 florets), longest vase life (14.8 days), greatest N (1.53%), P (0.28%), and K (0.64%) concentrations, and largest corm diameter (4.68 cm) and mass (22.25 g). The highest total protein and proline concentrations were observed with the combined application of MLE + GA + SA. Our findings suggested that MLE either alone or in combination with other plant growth regulators not only increased the yield and quality of cut spikes, but also prolonged the vase life of cut gladiolus.
Global climate change and associated adverse abiotic stress conditions such as drought, salinity, heavy metals, waterlogging, extreme temperatures, oxygen deprivation, etc., greatly influence plant growth and development, ultimately affecting crop yield and quality, as well as agricultural sustainability in general. Plant cells produce oxygen radicals and their derivatives, so-called reactive oxygen species (ROS) during various processes associated with abiotic stress. Moreover, the generation of ROS is a fundamental process in higher plants employs to transmit cellular signaling information in response to the changing environmental conditions. One of the most crucial consequences of abiotic stress is the disturbance of the equilibrium between the generation of ROS and antioxidant defense systems triggering the excessive accumulation of ROS and inducing oxidative stress in plants. Notably, the equilibrium between the detoxification and generation of ROS is maintained by both enzymatic and non-enzymatic antioxidant defense systems under harsh environmental stresses. Although this field of research has attracted massive interest, it largely remains unexplored, and our understanding of ROS signaling remains poorly understood. In this review, we have documented the recent advancement illustrating the harmful effects of ROS, antioxidant defense system involved in ROS detoxification under different abiotic stresses, and molecular cross-talk with other important signal molecules such as reactive nitrogen, sulfur, and carbonyl species. In addition, state-of-the-art molecular approaches of ROS-mediated improvement in plant antioxidant defense during the acclimation process against abiotic stresses have also been discussed.
The postharvest physiology of cut flowers is largely dependent on vase life, which is the maximum number of days before flower senescence. The use of tree bark extracts (major forest plant residues), as an eco-friendly and natural antioxidant preservative in holding solutions, is a novel tool for extending flower longevity. The morphological, physiological, biochemical, and genetic responses of Gladiolus grandiflorus cut spikes to Magnolia acuminata and Taxus cuspidata bark extracts as additives in holding solutions were investigated. G. grandiflorus subjected to bark extracts as well as catechin and protocatechuic acid (main phenols) displayed significant increased longevity (up to 18 days), an increased number of open florets, and increased floret fresh weight. Increases in the relative water content, leaf chlorophyll, carotenoids, soluble sugars, and protein content were observed in addition to a reduction in microbial growth in the cut spikes. Gas exchange parameters were higher in the bark extract treatments than in the controls. Higher antioxidant activities were detected and associated with increased superoxide dismutase and catalase enzyme activities and reduced H2O2 accumulation. The bark extract treatments associated with reduced expression of GgCyP1 (produces cysteine protease) and increased expression of both GgDAD1 (defends against apoptotic activity) and GgEXPA1 (regulates petal expansion). Several mechanisms were implicated in these effects, including maintenance of water content, enhanced management of reactive oxygen species (ROS), increased sugar and protein composition, and control of microbial growth. Thus, bark extracts and isolated phenols could be developed as an eco-friendly, non-toxic, and cost-effective natural preservative for cut gladiolus flowers.
Gladiolus is one of the most popular cut flower crops that manifest postharvest problems of rapidly losing the aesthetic value and short vase life that cause quality loss. The study was therefore carried out to investigate whether moringa leaf extract (MLE) has the ability to act as postharvest preservative solution to improve the quality and longevity of gladiolus spikes. Gladiolus spikes were subjected to various concentrations (0, 1, 2, 3, 4%) of MLE in vase solution. All MLE concentrations significantly extended the vase life and resulted in 10 days longer than the control when 3% MLE was applied. MLE treatment also improved the floret opening and reduced the weight loss of cut spikes. The relative water content (RWC), chlorophyll content, and membrane stability were considerably maintained while the microbial growth was suppressed in vase solution by MLE treatments. Also, malondialdehyde (MDA) and H 2 O 2 production was significantly suppressed by MLE treatments. MLE significantly increased the total phenolics and the activities of antioxidant enzymes (CAT and POX) in the florets. These ameliorative effects of MLE were more pronounced by the concentration 3% and further higher level causes no improvement in cut gladiolus spike longevity and quality. It is concluded that MLE showed these effects via alleviation the oxidative stress induced in the cut spike, maintaining photosynthetic pigments and water relations. We recommend MLE to be applied as a potential and promising eco-friendly alternative to common chemicals used in preservative solutions of cut flowers. MLE could also be commercialized as a novel floral preservative for future floral industry application.
Corchorus olitorius is mainly cultivated in Africa and is used in the human diet for its nutraceutical
proprieties. In this work, C. olitorius was grown in a floating system using a standard (NS100%) or
halved (NS50%) nutrient solution. Yield was evaluated at harvest when plants reached the baby leaf
stage. Quality of leaves was estimated by measuring sugars, nitrate, chlorophylls, carotenoids,
polyphenols, and anthocyanins. Yield was similar to other common leafy vegetables cultivated in
floating systems. Analytical determinations showed good levels of antioxidant compounds and
sugars. Mineral contents were relevant for Ca, Mg and Fe in comparison with C. olitorius cultivated
in soil and other common leafy vegetables. Results showed these plants had healthy characteristics
for human nutrition, in particular for women and children. C. olitorius had a good performance in
the floating system with yield ranging from 0.8 to 2.4 kg m−2. Mineral nutrient levels were higher
than in the major leafy vegetables. Nutrient solutions influenced anthocyanin accumulation (+37%
in NS50% in spring and +48% in NS50% in summer). Leaf nitrate content was –50% in NS50% at
spring cultivation. The overall quality parameters suggest that C. olitorius can be an optimal
candidate for baby leaf production in the fresh cut leafy vegetable industry.
The relatively brief postharvest life of most cut flowers and potted flowering
plants can be extended by a range of technologies. Studies have shown that vase
life is negatively correlated with respiration after harvest, so prompt cooling to
the lowest safe storage temperature is a key to long-distance transport of these
perishable crops. Forced air cooling is the method of choice for cut flowers, and
vacuum cooling has been shown to be very effective for cooling potted plants. In
contrast to some other horticultural crops, controlled and modified atmospheres
seem to have little effect on petal respiration, and these techniques have not
proved commercially useful in the marketing of many cut flowers. Low temperatures
are also important in managing the effect of other factors contributing
to early senescence, including water loss, the effects of ethylene, leaf yellowing,
and the growth of diseases, particularly caused by Botrytis cinerea. Ornamentals
originating in the tropics and subtropics cannot be cooled below 10!C because
they rapidly show the symptoms of chilling injury. Chemical strategies to
improve the life of ornamentals include the application of abscisic acid to
reduce water loss, particularly in potted and bedding plants, pretreatment with
the volatile ethylene inhibitor 1-methylcyclopropene (1-MCP) to prevent the
effects of endogenous or exogenous ethylene, treatment with gibberellins or
cytokinins (CKs), which often delay leaf yellowing and may increase bud
opening and flower life. Thidiazuron, a nonmetabolized CK, has proven particularly
effective for this purpose. A new strategy for inhibiting the growth of
B. cinerea on floral tissues is to treat them with low concentrations of hypochlorite.
Floral senescence is an active process with many of the hallmarks of
programmed cell death. Molecular analysis has revealed a large number of
candidate genes with possible roles in senescence and remobilization. Virusinduced
gene silencing has been used to evaluate the potential role of some of
these genes, particularly regulatory genes such as transcription factors and
kinases, although none has yet been identified as a key controller. Ornamentals
are particularly suited to testing transgenic strategies for extending shelf-life,
and we report results of experiments using constructs where inducible promoters
are used to drive genes that extend flower life. Of particular interest is the
dramatic extension of longevity resulting from silencing a component of the 26S
proteasome, which indicates the importance of targeted protein degradation in
control of floral senescence, and could serve as a strategy for extending the life of
ethylene-insensitive ephemeral flowers. Future research will undoubtedly
focus on providing better germplasm by using traditional, genomic assisted,
and/or molecular breeding approaches for improving the postharvest performance
of ornamentals.
Cut flowers of Dianthus caryophyllus L. cv. Asso were treated with 8-hydroxyquinoline sulphate (8-HQS) at 200 and 400 ppm with or without sucrose at 50 g l-1, silver thiosulphate (STS) at 0.2 and 0.4 mM with or without sucrose at 50 g l-1, and 1-methylcyclopropene (1-MCP) at 0.3, 0.5 and 0.7 g m-3 for 6 h to study the effect of these chemicals on post-harvest quality. 8-HQS treatments increased the vase life and the percentage loss of initial fresh weight compared to the control. In addition, the vase life was longer when sucrose was applied in combination with 8-HQS. The best treatment involved 400 ppm 8-HQS + 50 g l-1 sucrose. All the concentrations of STS prolonged the vase life and fresh mass compared to the control. The best treatment was STS at 0.4 mM with or without sucrose. All levels of 1-MCP prolonged the vase life and increased the fresh weight in comparison with the control. The best treatment in this respect was 1-MCP at 0.5 g m-3 for 6 h. The chlorophyll content (chl a and chl b) in the leaves was higher than the control in the best treatment of each chemical.
Bacterial distribution, both external (epiphytic) and internal (endophytic), on Gerbera jamesonii L. cv.
Provence and its relationship to gerbera stem break and ethylene production were investigated. The greatest number
of epiphytic bacteria was found at capitulum level and 20 cm below. Three genera of bacteria were identified:
Acinetobacter, Bacillus and Pantoea. A silver-nitrate solution greatly reduced ethylene production in cut flowers.
The use of acid fuchsin solution revealed an occlusion of the xylem vessels, probably due to bacterial cells. The
bacteria Acinetobacter, Pantoea and Bacillus appeared to be involved in stem break once their populations reached
105 cfu g-1 of stem tissue.
The vase life of cut flowers and foliage is often shortened by vascular occlusions that constrict vase solution supply. Reductions in stem conductivity are typically caused by blockage of cut stem ends and xylem conduits by microbes, physiological plugging, and disruption of water columns in xylem vessels by cavitation and air emboli. Cut flower and foliage longevity can be greatly affected by the chemical composition of the vase solution. Provision of biocides prolongs the vase life of numerous species. A broad range of biocides has been suggested to prevent the proliferation of microorganisms in vase solutions; however, their assumed antimicrobial action may be confounded by their other physicochemical effects. In this context, the response of cut stems to biocides may also vary according to the cut flower or foliage type, the specific microorganisms involved, and other vase solution ingredients. This paper explores the efficacy and multifunctional roles of vase solution biocidal agents used in industry and by researchers for cut flowers and foliage.
The object of the work is to evaluate whether rhizobacteria populating dry salty environments can increase resistance in tomato to salt stress. Seven strains of plant growth-promoting bacteria that have 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity were isolated from soil samples taken from the Arava region of southern Israel. Following growth of these seedlings in the presence of 43 mM NaCl for 7 weeks, the bacterium that promoted growth to the greatest extent was selected for further study. DNA analysis of the 16S RNA indicated that the selected bacterium was Achromobacter piechaudii. This bacterium significantly increased the fresh and dry weights of tomato seedlings grown in the presence of up to 172 mM NaCl salt. The bacterium reduced the production of ethylene by tomato seedlings, which was otherwise stimulated when seedlings were challenged with increasing salt concentrations, but did not reduce the content of sodium. However, it slightly increased the uptake of phosphorous and potassium, which may contribute in part to activation of processes involved in the alleviation of the effect of salt. In the presence of salt the bacterium increased the water use efficiency (WUE). This may suggest that the bacterium act to alleviate the salt suppression of photosynthesis. However, the detailed mechanism was not elucidated. The work described in this report is a first step in the development of productive agricultural systems in saline environments.
Flowering duration and post-harvest life of flowers are dependent upon their senescence. The present investigation discerns the toppling of different physiological and biochemical parameters that shift floral bud to senescent flower. Chrysanthemum morifolium L. (Chrysanthemum) and Gladiolus grandiflora Hort. (Gladiolus) are two important crops occupying leading positions in cut flower industry. The tepals of Gladiolus and Chrysanthemum were evaluated at different developmental stages, ranging from tight bud to senescence to identify the stage to extend flowering duration on the plant or post-harvest life of flower through chemical manipulation. The physiological and biochemical parameters, viz., membrane stability index, relative water content, total soluble sugars, proteins, and phenols increased during initial stages of development and then decreased towards later stages. The flower colour is dependent upon the pigments, viz., anthocyanins and carotenoids that also increased from early developmental stages to fully open stage, but declined towards senescence. The increase in content of metabolites during earlier stages of flower development or flower opening indicated that developing flowers act as a sink for photo assimilates, but towards maturity, they act as a source and transfer its metabolites to developing parts of the plant. Thus, the pattern of metabolites depicted that chemical manipulation through plant growth substances could be done at loose bud stage or partially opened flowers in Chrysanthemum and colour break stage or half opened floret in Gladiolus that could delay senescence and improve their post-harvest performance.
Gladiolus (Gladiolus grandiflorus L.) is a commercial ornamental plant cultivated for its inflorescences. Improving quality and vase life (VL) of gladiolus inflorescences is an important research topic for both the growers and the sellers. For this reason, we studied the effects of preharvest potassium (K⁺) foliar application on postharvest physiological and biochemical changes. Our hypothesis was that K⁺ foliar application could improve preharvest physicochemical responses such as photosynthesis and stomatal conductance and also improve postharvest quality by reducing oxidative damage in cells. In series of pot experiments we studied the effects of 0 %, 1 %, 2 % and 3 % K⁺ on net CO2 assimilation (As), stomatal conductance (gs), transpiration (E), water use efficiency (WUE), soluble sugars (SS), total soluble proteins (TSP), VL and antioxidant activity of gladiolus cv. Manhatten. The results showed that K⁺ application, especially on inflorescences treated with the highest K⁺ concentrations, positively affected As and WUE. This resulted in higher SS and TSP by 45 % and 93 %, respectively. Potassium supplementation improved VL and reduced postharvest oxidative stress by enhancing superoxide dismutase (SOD) and catalase (CAT) enzyme activities. The 3 % K⁺ treatments increased SOD by up to 107 % and CAT by up to 188 %, compared to the control inflorescences. K⁺ treatments at 3 % significantly reduced malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents, by up to 42 % and 57 %, respectively indicating a strong reduction of oxidative stress. We suggest that, K⁺ supplementation strategies may improve postharvest quality of cut gladiolus inflorescences and extend VL by enhancing antioxidant activity and reduce oxidative stress.
Keeping quality is frequently terminated by adverse water relations or oxidative stress. This study was designed to evaluate whether postharvest application of single, multi-walled carbon nanotubes and nanographene oxide (SWCNTs, MWCNTs, and NGO respectively) can improve keeping quality in rose, along with the processes involved. Dose-response curves were realised by applying five concentrations of SWCNTs, MWCNTs, and NGO (0–80, 0–80, and 0–2 mg L⁻¹ respectively) either once as a foliar spray or continuously in the holding solution of different rose cultivars. At optimal concentration, CNTs and NGO through either application method extended keeping quality. CNTs improved water balance by promoting water uptake more than water loss, whereas NGO did not. Each nanomaterial at optimal concentration was also employed to assess various parameters underlying keeping quality. CNTs generally enhanced leaf stomatal conductance and transpiration. CNTs and NGO attenuated chlorophyll degradation, electrolyte leakage and lipid peroxidation due to the amplified triggering of both enzymatic and non-enzymatic antioxidants. In conclusion, the extension of keeping quality by postharvest application of CNTs and NGO was characterised by different modes of action. Both upgraded the antioxidant status, while CNTs additionally promoted water relations.Abbreviations: APX, ascorbate peroxidase; CAT, catalase; CNTs, carbon nanotubes; DW, dry weight; FW, fresh weight; GAE, gallic acid equivalent; NGO, nanographene oxide; MDA, malondialdehyde; MWCNTs, multi-walled CNTs; NBT, nitro-blue tetrazolium chloride; POD, peroxidase; RH, relative air humidity; ROS, reactive oxygen species; RUE, rutin equivalent; RWC, relative water content; SOD, superoxide dismutase; SWCNTs, single-walled CNTs.
Senescence is the major physiological process that influence the quality of cut flowers. Among cut flowers, gladiolus known for its glamour, perfection and colorful spikes occupies leading position in Indian as well as international markets. Thus, in the present investigation, evaluation of sodium nitroprusside (nitric oxide, NO donor) as holding solution on biochemical and physiological parameters affecting postharvest life of gladiolus spikes (varieties: Punjab Glad-1 and Punjab Glad-2) was done. Gladiolus spikes harvested at tight bud stage were kept in different solutions viz. 50, 100, 150, 200 mg L−1 sodium nitroprusside (SNP); 2% sucrose and 400 mg L−1 aluminium sulphate; water as control. The holding solution of 100 mg L−1 SNP extended the vase life of Punjab Glad-1 from 7 days in control to 13 days and Punjab Glad-2 from 6 days in control to 11 days. The results revealed that holding solution @SNP 100 mg L−1 improved membrane stability index and relative water content, increased total soluble sugars, total soluble proteins, catalase and peroxidase activity during floret development more in Punjab Glad-1 than Punjab Glad-2 that enhanced the number of floret opened at one time, percent floret opened, floret size, solution absorbed and ultimately vase life. Thus, 100 mg L−1 SNP as a holding solution could improve the postharvest quality of gladiolus spikes by influencing biochemical and physiological attributes.
Gladiolus is among the most versatile cut flowers and available in an array of colors. However, it has a relatively short vase life, associated with increased postharvest losses and decreased quality. Commercially, synthetic chemicals are applied to enhance its postharvest vase life, but in general they are not environmentally friendly. The current research aimed to evaluate whether natural plant extracts can serve as effective preservatives to extend the postharvest vase life of gladiolus spikes. There is no record in the literature of the use of leaf extract of Calotropis procera as a vase-life extender for cut flowers, though its leaf extract has been shown to have antimicrobial, antioxidant and insecticidal activity. In contrast, leaf extract of Moringa sp. and Mentha sp. are commonly known to extend the vase life. The leaf extracts of Moringa olifera, Mentha piperita and Calotropis procera at 2 and 4 % were used in holding solutions to compare their effects on vase life, physiological and metabolic activities of gladiolus cut spikes. In current results, Calotropis procera leaf extract (CPLE) at 2 % exhibited maximum vase life up to 14.50 days, open florets (64 %) and RFW (40 %) in comparison to Moringa olifera leaf extract (MOLE) and Mentha piperita leaf extract (MPLE). Similarly, maximum RWC (41 %), MSI (30 %), and CAT (66 %), POX (74 %), SOD (57 %) and reduced bacterial count (64 %) was also recorded in 2 % CPLE than MOLE and MPLE over untreated spikes. The cut spikes preserved in 2 % MOLE described maximum Chl a, (71 %), Chl b (64 %) and Car (49 %) contents than CPLE. Hence, CPLE at 2 % appears to be an effective natural preservative to prolong the vase life of gladiolus cut spikes.
Sunlight includes UVA (320–400 nm). Since it is irrelevant for driving photosynthesis, less recognition is given to its usefulness in indoor cultivation. We examined how the cultivation under different UVA levels (0, 10 and 40 μmol m−2 s−1) affects the lettuce postharvest quality by evaluating the temporal dynamics of several underlying aspects, including weight loss, chlorophyll fluorescence, protein content, primary energy reserves (starch, sugars), pigments (chlorophyll, carotenoids), the activity of enzymes related to enzymatic browning [phenylalanine ammonia lyase, polyphenol oxidase (PPO)], the activity of antioxidant machinery enzymes (superoxide dismutase, catalase), the accumulation of non-enzymatic antioxidants (polyphenols, ascorbic acid) and the accumulation of reactive oxygen species (ROS; H2O2, O2−). Evaluations were conducted (5 d intervals) on dark-stored excised leaves for 15 d (16 ℃, 70 % relative air humidity). Control samples gradually underwent a decrease in both primary energy reserves and protein content. They also suffered from color degradation owing to both a decrease in chlorophyll content and an enhanced PPO activity. Increased electrolyte leakage was also observed as a result of enhanced ROS levels. The low UVA level clearly improved all quality parameters, whereas the application of high UVA intensity caused limited effects in comparison to the control. In the former case, ROS accumulation was counteracted by an enhanced stimulation of the non-enzymatic and enzymatic antioxidant machinery. Overall, the results show that the promotive effect of UVA during cultivation on lettuce nutritional quality and shelf-life is strongly intensity-dependent and is mediated by diverse processes.
In the present study, we demonstrated that borage (Borago officinalis L.) seed oil subjected to immobilized lipase pretreatment are enriched with linoleic acid (LNA, 18:2n‐6), γ‐linolenic acid (GLA, 18:3n‐6), and oleic acid (OLA, 18:1n‐9). We further showed that lipase‐treated borage oil (LT‐BOL) regulates the activity and degradation of tyrosinase, an important enzyme implicated in the synthesis of melanin in murine melanocytes, B16F10. LT‐BOL and its free fatty acid components reduced the levels of melanin and tyrosinase in melanocytes with GLA exerting similar or stronger effects compared with LNA and OLA. The brightening efficacy of LT‐BOL on melanin metabolism in humans was tested by an 8‐week, double‐blind, randomized clinical trial, which enrolled 21 Korean female adults (mean age 48.57 ± 3.28). Visual evaluation showed that cream containing 1% LT‐BOL significantly decreased (p < 0.05) melasma on the treated skin area after 6 and 8 weeks. The analysis of the skin brightness using Chromameter CR‐400 confirmed that the brightness of the treated area was significantly increased (p < 0.01) after 4, 6, and 8 weeks. Together, our results suggest that LT‐BOL may be suitable as a natural skin whitening cosmeceutical product.
The vase life of industrial cut flowers is relatively short and hence seeking eco-friendly strategies to extend its commercially needed. This research was consequently undertaken to study either moringa leaf extract (MLE) or moringa seed extract (MSE) can be applied as a natural preservative to prolong the vase life of cut roses. Both applications were selected and tested because they are natural and have no environmental hazards. Cut flowers of Rosa hybrida cv. ‘Upper Class’ were overnight pulsed in either MLE or MSE at 1:40, 1:30, 1:20, 1:10 (extract/water, v/v) and then transferred to distilled water. The vase life was significantly extended by MLE or MSE, more so with 1:30 and 1:20 extracts. Both MLE and MSE resulted in 8 and 5 days, respectively, longer than the untreated flowers. Pulsing with MLE or MSE significantly maintained the relative water content (RWC) and suppressed the microbial growth at the stem base. However, although SEM investigation showed few bacteria on the cut ends of the flowering stems pulsed with MLE or MSE even on day 5, there was no visual bacterial blockage observed in the xylem vessels. Contrary, the cut ends of untreated flowers were completely covered with bacterial cells and a lot of bacteria were detected inside the xylem vessels. SEM investigation also revealed that MLE or MSE treatment reduced the stomatal aperture which was widely opened in untreated flowers. Additionally, MLE or MSE pulsing increased proline content, reduced H2O2 production and lipid peroxidation, enhanced total phenol content, radical scavenging and the activity of CAT and POX enzymes, which altogether resulted in maintained membrane stability. Expression of RhPIP1, RhTIP1 and RhLAC genes were considerably induced in control samples up to day 4 relative to MLE or MSE treated flowers, but no significant difference was observed between both moringa extracts in this respect. In conclusion, MLE or MSE treatment extended the vase life of cut roses via keeping water relations and enhancing the antioxidant machinery, the impact was more pronounced with MLE. Therefore, MLE as a novel preservative is recommend for future using in floral industry.
Leaf chlorophyll is essential to harvest light energy to drive photosynthesis. Yet, most of studies of leaf chlorophyll concentration (Chl) have typically been limited to few species or sites, and there has been little understanding of its variation among species of contrasting environments, or across forests differing in gross primary productivity (GPP). We measured mass-based foliar Chl concentrations (Chl a, Chl b, and total Chl) for 937 species of nine Chinese forests ranging from tropical to cold-temperate regions. Total Chl varied by over ten-fold from 1.45 to 19.2 mg g⁻¹ (mean: 5.54 mg g⁻¹), and differed among plant functional groups. At the community level, total Chl decreased with increasing latitude. The ratio of Chl a/b decreased from trees to shrubs to herbs, consistent with adaptation to contrasting irradiance, i.e., overstory vs. understory. Total Chl was positively related to leaf N and P concentrations, as would be expected to optimize photosynthesis and carbon fixation. Across forests, GPP was positively correlated with community-averaged Chl (r = 0.57; P < 0.01), a new case of a linkage between leaf traits and ecosystem function at regional to continental scale. Our findings revealed variation in Chl from tropical to cold-temperate forests, and the linkage of leaf Chl with ecosystem function, enhancing our ability to parameterize vegetation models.
Postharvest treatments with nano-silver (NS) alleviate bacteria-related stem blockage of some cut flowers to extend their longevity. Gladiolus (Gladiolus hybridus) is a commercially important cut flower species. For the first time, the effects of NS pulses on cut gladiolus ‘Eerde’ spikes were investigated towards reducing bacterial colonization of and biofilm formation on their stems. As compared with a deionized water (DIW) control, pulse treatments with NS at 10, 25 and 50 mg L⁻¹ for 24 h significantly (P ≤ 0.05) prolonged the vase life of cut gladiolus spikes moved into vases containing DIW. The NS treatments enhanced floret ‘opening rate’ and ‘daily ornamental value’. Although there were no significant differences among NS treatments, a 25 mg L⁻¹ NS pulse treatment tended to give the longest vase life and the best ‘display quality’. All NS pulse treatments significantly improved water uptake by and reduced water loss from flowering spikes, thereby delaying the loss of water balance and maintaining relative fresh weight. Fifty (50) mg L⁻¹ NS pulse-treated cut gladiolus spikes tended to exhibit the most water uptake and highest water balance over the vase period. However, there was no significant difference between 25 and 50 mg L⁻¹ NS pulse treatments. Observations of stem-end bacterial proliferation during the vase period on cut gladiolus spikes either with or without NS pulse treatments were performed by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). As compared to the control treatment, they revealed that the 25 mg L⁻¹ NS pulse treatment effectively inhibited bacterial colonization and biofilm formation on the stem-end cut surface and in the xylem vessels, respectively. In vitro culture of the bacterial microflora and analysis of biofilm architecture using CLSM revealed that NS treatment restricted bacterial biofilm formation. After static culture for 24 h at 35 °C with 25 mg L⁻¹ NS in the medium, no biofilm form or structure was evident. Rather, only limited bacterial cell number and scanty extracellular polysaccharide (EPS) material were observed. In contrast, mature bacterial biofilm architecture comprised of abundant bacteria interwoven with EPS formed in the absence of NS.
Early senescence is the main limiting factor during the marketing of cut flowers. The current experiments were aimed at understanding the effects of pre- or post-transport application of salicylic acid (SA) on physicochemical characteristics affecting vase life of cut flower spikes of gladiolus cv. Amsterdam. SA was foliar sprayed at 0, 0.5, 1 or 2 mM concentrations on harvested flowers before or after simulated transport to local market, in order to evaluate its effect on post-harvest qualities and physiochemical parameters. The results showed that 0.5 mM SA significantly increased flower vase life, as well as membrane stability, anthocyanin and flavonoid concentrations, and activities of catalase and superoxide dismutase enzymes in the flower petals. The relative fresh weight was not significantly affected by SA foliar treatment applied pre- or post-transport. Significant reduction was observed in lipid peroxidation of the SA-treated flowers, compared with the control group. The results suggest that foliar application of SA, especially at low concentration (0.5 mM), improves gladiolus vase life through modulating its antioxidative system and reducing lipid peroxidation. This treatment can be easily applied for commercial use.
The present review, an update of van Doorn (1997), covers topics such as the role of xylem and phloem in providing water to flowers in intact plants, the artificial reduction of stomatal opening, xylem blockage (including work on cavitations), the effect of ions in the vase solution on the water flow rate in the xylem, the possible formation of small air bubbles (not cavitations) in the xylem when the vase solution passes through, the idea of using artificial tap water rather than deionized water as a standard vase solution, and the effects of ethylene as a result of water stress. Recent work on hydraulic conductance in isolated stem segments suggests that small, but coalescing, air bubbles are formed in the xylem conduits, which results in a decrease of hydraulic conductance. The importance of this finding for cut flowers remains to be investigated. A new type of physiological xylem blockage has been found, which was prevented by chemicals that inhibit either polyphenol oxidase/catechol oxidase (PPO) or peroxidase. Several possible mechanisms might explain this xylem occlusion, such as the formation of lignin, suberin, and quinones or semiquinones. S-carvone, which is a phenylalanine ammonia lyase antagonist, also inhibits a physiological blockage, which might be the same as the one inhibited by antagonists of PPO or peroxidase. This review also evaluates the recent proposal to replace deionized water as a standard vase solution in research on cut flowers with a specific artificial tap water. This proposal is considered incorrect, since this artificial tap water has been shown thus far to extend the vase life of only one cultivar of one species (Chrysanthemum 'Cassa'). In other flowers, the artificial tap water had no effect or was detrimental. Deionized water should therefore remain the standard vase solution, in experiments with cut flowers and cut foliage.
The activation of oxygen stress-related enzymes was compared in regenerating and non-regenerating tulip bulb scale explants and regenerating stalk explants. The phospholipid composition of scale explants showed an increase of linolenic acid (1–15%) and a decrease in linoleic acid (70–55%). After incubation it was comparable to that of stalk explants in which no changes were observed. In all tested systems an increase in activity of catalase, peroxidase, SOD, lipoxygenase, polyphenoloxidase and phenylalanine ammonia lyase, was observed during incubation of the explants. The reaction can be divided into two phases. The first one (observed for scale explant lipoxygenase and to a lesser extent for SOD) occurs rapidly (1–2 h) after cutting the explants and appears to be wounding related. In the second phase (observed for all enzymes), starting during the first week of incubation, wound healing and regeneration can be observed. The activation of catalase, peroxidase and phenylalanine ammonia lyase was comparable in all tested systems and appears not to be related with the differences in tissue culture performance. In the second phase, the activity of lipoxygenase, peroxidase, catalase and phenylalanine ammonia lyase decreases in regenerating explants, while in non-regenerating explants they remain high. Our conclusion from these results is that oxidative damage is not the prime cause of the low regenerability of tulip bulb scale explants.
Cut flowers face the problem of short display life and lose their aesthetic value rapidly. In order to enhance the vase life of gladiolus, its cut spikes were subjected to different levels of gibberellic acid (GA3), viz., 0, 25, 50, 100 and 200 mg L−1 in vase solution, during two consecutive years 2010 and 2011. The GA3 treatment significantly influenced the vase quality attributes and antioxidants capacity of gladiolus cut flowers. Gibberellic acid at 25 mg L−1 caused the longest time taken to open the floret and increased the floret opening, vase life duration and fresh weight. The highest antioxidative activities of superoxide dismutase and free radicals scavenging were also recorded with GA3 at 25 mg L−1. The highest peroxidase, catalase activity and the lowest membrane leakage were recorded with GA3 at 50 mg L−1. Present study concludes that GA3 applied at lower concentrations (25 mg L−1) renders greater beneficial effects on vase life quality, membrane stability and antioxidant activities in gladiolus cut spike, and further higher application rates cause no improvement in the flower longevity.
Publisher Summary This chapter discusses the analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent. Analyses of the Folin-Ciocalteu (FC) type are convenient, simple, and require only common equipment and have produced a large body of comparable data. Under proper conditions, the assay is inclusive of monophenols and gives predictable reactions with the types of phenols found in nature. Because different phenols react to different degrees, expression of the results as a single number—such as milligrams per liter gallic acid equivalence—is necessarily arbitrary. Because the reaction is independent, quantitative, and predictable, analysis of a mixture of phenols can be recalculated in terms of any other standard. The assay measures all compounds readily oxidizable under the reaction conditions and its very inclusiveness allows certain substances to also react that are either not phenols or seldom thought of as phenols (e.g., proteins). Judicious use of the assay—with consideration of potential interferences in particular samples and prior study if necessary—can lead to very informative results. Aggregate analysis of this type is an important supplement to and often more informative than reems of data difficult to summarize from various techniques, such as high-performance liquid chromatography (HPLC) that separate a large number of individual compounds .The predictable reaction of components in a mixture makes it possible to determine a single reactant by other means and to calculate its contribution to the total FC phenol content. Relative insensitivity of the FC analysis to many adsorbents and precipitants makes differential assay—before and after several different treatments—informative.
An experiment was conducted with three wheat genotypes differing in their sensitivity to moisture and/or temperature stress to study the relationship of the chloroplast antioxidant system to stress tolerance. Both moisture stress and temperature stress increased glutathione reductase and peroxidase and decreased membrane stab-iltty, chlorophyll content and chlorophyll stability index in all genotypes. Under moisture stress. DL 153–2 showed the highest membrane stabihty index, chlorophyll content, chlorophyll stability index, glutathione reductase activity and peroxidase activity. However, under elevated temperature conditions, HD 2285, and to a lesser extent DL 153–2, showed higher membrane stability, chlorophyll content and chlorophyll stability index and activities of glutathione reductase and peroxi-dase. Raj 3077, which is sensitive to both drought and temperature stress, showed the lowest membrane stability, chlorophyll content and chlorophyll stability index and glutathione reductase and perosidase activity under elevated temperature as well as drought conditions. Thus, it can be concluded that tolerance of the genotype to moisture and/or temperature stress is closely associated with its antioxidant enzyme system.
Proline, which increases proportionately faster than other amino acids in plants under water stress, has been suggested as an evaluating parameter for irrigation scheduling and for selecting drought-resistant varieties. The necessity to analyze numerous samples from multiple replications of field grown materials prompted the development of a simple, rapid colorimetric determination of proline. The method detected proline in the 0.1 to 36.0 moles/g range of fresh weight leaf material.
The aqueous solutions in which stems of cut flowers had been placed were sampled in order to measure the bacterial count. The study involved keeping solutions used for eight flower species (Rosa hybrida L., Gerbera jamesonii H. Bolus, Dianthus caryophyllus L., Tulipa hybrids, Lilium hybrids, Chrysanthemum morifolium Ramat., Iris hybrids and Freesia hybrids). In a total of 3385 samples taken, the numbers of bacteria found were relatively low at the grower level, but became successively higher at auctions, wholesalers and retailers. Pretreatment solutions (containing silver thiosulphate, gibberellic acid or a mixture of these compounds) used by growers contained a high number of bacteria. When chlorine was used as an antibacterial chemical, the number of bacteria was low. The use of flower preservatives (which contain antibacterial chemicals and sugars) did not, however, result in a decrease of bacterial numbers. The results suggest that the number of bacteria, especially at the retail level, was often high enough to reduce flower longevity.
Grevillea ‘Crimson Yul-lo’ inflorescences have cut flower potential, but their vase life is short. End of vase life is characterized by early wilting. The possibility of physiologically mediated stem end blockage was investigated. Hydraulic conductance of 2 cm long stem end segments declined rapidly and remained lower throughout vase life than that of 2 cm long stem segments from immediately above. Re-cutting daily to remove basal 2 cm stem ends increased solution uptake, delayed declines in inflorescence water potential and water content, and improved inflorescence vase life. S-carvone is a potential inhibitor of wound related suberin formation, via inhibition of phenylalanine ammonia-lyase. Vase solution treatments with S-carvone (0.318 and 0.636 mM) delayed the decline in hydraulic conductance of basal 2 cm long stem end segments and decreases in vase solution uptake and relative fresh weight of cut stems, and extended vase life. Treatments with the catechol oxidase inhibitor 4-hexylresorcinol (2.5–10 mM) also delayed stem end blockage. These findings suggest that stem end blockage in cut G. ‘Crimson Yul-lo’ stems is physiologically mediated.
Senescence is a highly regulated process terminating with programmed cell death (PCD). Floral senescence, and in particular petal senescence, forms an interesting model to study this process in that floral lifespan is species specific and linked to biological function. A feature of petal senescence is a rise in reactive oxygen species (ROS) and a change in redox balance. A key question is whether this is merely a consequence of de-regulation of antioxidant systems as cells enter PCD, or whether the rise in ROS may have a regulatory or signalling function. An important division in the physiology of floral senescence is between species in which ethylene is a key regulator, and those in which it appears not to perform an important regulatory role. Another important question we can therefore ask is whether the redox and ROS changes have the same significance in species with different physiologies. Transcriptomic studies in ethylene-sensitive and -insensitive species allow us to further determine whether changes in the activity of ROS-scavenging enzymes are transcriptionally regulated during floral senescence. Finally, it is important to assess how a signalling role for ROS or redox status would fit with known plant growth regulator (PGR) control of floral senescence.
The rapid evaluation of antioxidant activity of crude borage (Borago officinalis L.) extract was determined by using DPPH free radical method. This borage extract resulted in a rapid decrease of the absorbance and showed very high hydrogen-donating capacity towards the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical. A new HPLC-DPPH on-line method was applied for a screening of several radical scavenging components in this borage extract as well as for quantitative analysis. This on-line HPLC-DPPH method was developed using a methanolic solution of DPPH-stable radical. The HPLC-separated analytes reacted post-column with the DPPH solution in methanol. The induced bleaching was detected as a negative peak photometrically at 515 nm. The separation of antioxidative components was carried out by gradient HPLC with mobile-phase composition ranging from 2% to 80% acetonitrile with 2% acetic acid in water, UV detection was carried out at 280 nm. The HPLC analysis of borage extract revealed the presence of several radical scavenging components in the borage extract. The results obtained from the chromatograms suggest that some compounds present in the extract possess high radical quenching ability. The dominant antioxidative compound in the crude extract of borage leaves was identified as rosmarinic acid.
Postharvest biology and technology of cut flowers and potted plants
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