Vase Period Research Articles

Extension of Vase Life by Nano-Selenium in Rosa hybrida

Vase life directly affects the ornamental value of cut flowers, and extending vase life has been a research focus in the floriculture industry. The antioxidant and antimicrobial properties of Nano-Se provide a new direction to extend the life of cut-flower vase life. In order to explore the postharvest quality of Nano-Se on cut-flower roses, this study treated cut-flower roses with different concentrations of Nano-Se (200, 400, and 600 mM) using a commercially available preservative solution as a base solution. The results showed that appropriate concentrations of Nano-Se significantly increased the vase life of cut-flower roses and helped to maintain high petal moisture content. Nano-Se at concentrations of 200, 400, and 600 mM extended the vase life of cut roses by 4.3, 5.7, and 3.7 d, respectively. As the vase period extended, the Nano-Se treatment group effectively delayed the decline in antioxidant enzyme activities such as peroxidase (POD) and catalase (CAT), maintained the soluble sugar (SS) and soluble protein (SP) contents in the cut roses, and inhibited the production of malondialdehyde (MDA) and hydrogen peroxide (H2O2), reducing their accumulation. A correlation analysis of the physiological indexes of cut roses showed that vase life was positively correlated with POD and CAT activities, SS and SP contents, and total phenolic acid content and negatively correlated with MDA and H2O2 contents. This study provides a solid theoretical basis for the diversification of preservatives and the development of new preservatives for fresh-cut roses, which is expected to provide significant economic benefits.

Silicon dioxide and selenium nanoparticles enhance vase life and physiological quality in black magic roses

In contemporary floriculture, particularly within the cut flower industry, there is a burgeoning interest in innovative methodologies aimed at enhancing the aesthetic appeal and prolonging the postharvest longevity of floral specimens. Within this context, the application of nanotechnology, specifically the utilization of silicon and selenium nanoparticles, has emerged as a promising approach for augmenting the qualitative attributes and extending the vase life of cut roses. This study evaluated the impact of silicon dioxide (SiO2-NPs) and selenium nanoparticles (Se-NPs) in preservative solutions on the physio-chemical properties of ‘Black Magic’ roses. Preservative solutions were formulated with varying concentrations of SiO2-NPs (25 and 50 mg L−1) and Se-NPs (10 and 20 mg L−1), supplemented with a continuous treatment of 3% sucrose. Roses treated with 20 mg L−1 Se-NPs exhibited the lowest relative water loss, highest solution uptake, maximum photochemical performance of PSII (Fv/Fm), and elevated antioxidative enzyme activities. The upward trajectory of hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels in petals was mitigated by different levels of SiO2 and Se-NPs, with the lowest H2O2 and MDA observed in preservatives containing 50 mg L−1 SiO2- and 20 mg L−1 Se-NPs at the 15th day, surpassing controls and other treatments. Extended vase life and a substantial enhancement in antioxidative capacity were noted under Se and Si nanoparticles in preservatives. The levels of total phenols, flavonoids, and anthocyanin increased during the vase period, particularly in the 50 and 20 mg L−1 Se-NPs and SiO2-NPs. Petal carbohydrate exhibited a declining trend throughout the longevity, with reductions of 8% and 66% observed in 20 mg L−1 Se-NPs and controls, respectively. The longest vase life was achieved with Se-NPs (20 mg L−1), followed by SiO2-NPs (50 mg L−1) up to 16.6 and 15th days, respectively. These findings highlight the significant potential of SiO2- and Se-NPs in enhancing the vase life and physiological qualities of ‘Black Magic’ roses, with SiO2-NPs showing broad-spectrum efficacy.

Early Detection of Botrytis cinerea Infection in Cut Roses Using Thermal Imaging.

Botrytis cinerea (B. cinerea) causes gray mold disease (GMD), which results in physiological disorders in plants that decrease the longevity and economic value of horticultural crops. To prevent the spread of GMD during distribution, a rapid, early detection technique is necessary. Thermal imaging has been used for GMD detection in various plants, including potted roses; however, its application to cut roses, which have a high global demand, has not been established. In this study, we investigated the utility of thermal imaging for the early detection of B. cinerea infection in cut roses by monitoring changes in petal temperature after fungal inoculation. We examined the effects of GMD on the postharvest quality and petal temperature of cut roses treated with different concentrations of fungal conidial suspensions and chemicals. B. cinerea infection decreased the flower opening, disrupted the water balance, and decreased the vase life of cut roses. Additionally, the average temperature of rose petals was higher for infected flowers than for non-inoculated flowers. One day before the appearance of necrotic symptoms (day 1 of the vase period), the petal temperature in infected flowers was significantly higher, by 1.1 °C, than that of non-inoculated flowers. The GMD-induced increase in petal temperature was associated with the mRNA levels of genes related to ethylene, reactive oxygen species, and water transport. Furthermore, the increase in temperature caused by GMD was strongly correlated with symptom severity and fungal biomass. A multiple regression analysis revealed that the disease incidence in the petals was positively related to the petal temperature one day before the appearance of necrotic symptoms. These results show that thermography is an effective technique for evaluating changes in petal temperature and a possible method for early GMD detection in the cut flower industry.

Postharvest bacterial succession on cut flowers and vase water.

In cut flowers, xylem occlusion or blockage by bacteria negatively affects water balance and postharvest quality. Many studies have used culture-based methods to examine bacterial populations in vase water and their effects on flower longevity. It is still unclear if and how bacterial communities at the 16S rRNA gene (16S) level change during the vase period and how such change might correlate with postharvest longevity. This study compared the sequences of 16S amplicons from 4 different types of flowers and their vase water over the course of 7 days (Rosa spp., Gerbera jamesonii, and two Lilium varieties). The relative abundance of plant chloroplast and mitochondria 16S decreased significantly over the course 7 days in all 4 flowers as bacterial diversity increased. Richness and evenness of the bacterial communities increased over time, as did the number of rare taxa and phylogenetic diversity. Bacterial communities varied with time, as well as by flower source, types, and sample location (water, stem surface, whole stem). Some taxa, such as Enterobacteriacea and Bradyhizobiaceae decreased significantly over time while others such as Pseudomonas spp. increased. For example, Pseudomonas veronii, implicated in soft rot of calla lily, increased in both whole stem samples and water samples from Gerbera jamesonii. Erwinia spp., which includes plant pathogenic species, also increased in water samples. This work highlights the dynamic and complex nature of bacterial succession in the flower vase ecosystem. More work is needed to understand if and how bacterial community structure can be managed to improve cut flower vase life.

Sensitivity Consequences of Ethylene in Determining the Vase Life of Eremurus spectabilis and E. persicus

Foxtail lily (Eremurus), as a medicinal-ornamental geophyte, has recently emerged in the cut flower market as a novel, commercially significant specialty cut flower (SCF). However, there is limited information about the sensitivity to ethylene of foxtail lily species for managing the ethylene-mediated senescence to prolong the vase life and maintain the ornamental quality of this flower. The purpose of the current study was to compare the ethylene production rates and patterns, as well as the responses to exogenous ethylene and ethylene inhibitors, between two species, E. spectabilis and E. persicus, to better understand the role of ethylene in Eremurus inflorescence senescence. The results revealed that exogenous ethylene (10 μL L−1), as a pulsing or continuous method, dramatically accelerated petal wilting in E. spectabilis and petal abscission in E. persicus. Furthermore, the rate and patterns of endogenous ethylene production varied significantly among the two investigated species. Interestingly, E. persicus exhibited a higher rate of ethylene production than E. spectabilis on the first day after harvesting, but the reverse was true at the end of the vase life (Day 4 of the vase period). The results revealed that the treatments with ethylene inhibitors considerably improved the water relations and vase longevity of both foxtail lily species. The vase life of E. spectabilis was dramatically enhanced by silver thiosulfate complex (STS) treatment (0.2 mM pulse for 24 h) from 5 d (control) to 7 d. Furthermore, 1-methylcyclopropene (1-MCP) at 0.5 and 1.0 μL L−1 markedly improved water uptake, relative fresh weight, and water balance and extended the vase life of cut inflorescences by ~2 d in E. spectabilis and E. persicus, compared with those of control cut inflorescences, respectively. This research revealed that ethylene is involved in controlling the senescence of foxtail lily flowers, and two tested species exhibited distinct forms of ethylene sensitivity, including abscission type in E. persicus and wilting-type in E. spectabilis. Collectively, these findings suggest that ethylene is involved in the senescence of cut foxtail lily inflorescence and that ethylene inhibitors can prolong vase life.

Application of Cytokinin under Modified Atmosphere (MA) Delays Yellowing and Prolongs the Vase Life of Davallia solida (G. Forst.) Sw. Leaves

Cut leaves of Davallia solida are widely used in bouquet greenery. However, the leaves wilt and yellow after seven days. Postharvest applications of exogenous cytokinins (CKs), a plant growth regulator (PGR), preventing senescence in many green leafy plants, were studied by pulsing cut D. solida leaves with 6-benzylamiopurine (BA) at a concentration of 100 ppm, or thidiazuron (TDZ) at a concentration of 10 μM for 24 h, compared with distilled water as a control, and then placing the ferns in a controlled room (21 + 2 °C, 70–80% relative humidity (RH), under cool-white fluorescent lights for 12 h/d). Pulsing with BA and TDZ delayed leaf yellowing while preserving chlorophyll (Chl) content. This was due to reduced Chl-degrading enzyme activities on day 8 of the vase life of the leaves, resulting in longer display life of 11.1 and 11.5 days, respectively. TDZ delayed Chl breakdown on day 8 of the vase life of leaves more than was the case for BA. Subsequently, leaves were pulsed in 10 μM TDZ, or distilled water for 24 h, and then 10 leaves from each treatment were packaged in a 25 × 30 cm, 25-μm thickness BOPP bag. All the packages were stored at 10 °C in 10 h/d light for one, two and three weeks, then unpacked and placed in distilled water. Pulsing with TDZ before one-week storage delayed leaf yellowing, maintained Chl content and extended their vase life to 9.6 days compared with one-, two-, and three-week control leaves, which had a vase life of 6.2, 5.8, and 3.6 days, respectively. After one week, the relative fresh weight of the leaves and water uptake did not alter between the control and TDZ groups. The activities of Chl degradation enzymes in the leaves of D. solida pulsed with TDZ prior to storage were significantly suppressed, related to higher Chl content and a lower percentage of leaf yellowing than the control, resulting in a longer vase life of 9.0 days, while the control lasted 7.0 days. A 10 µM TDZ pulsing treatment significantly prevented the yellowing of D. solida fronds during the vase period or storage period, and one-week storage under MA with light conditions is recommended for retaining postharvest quality after storage.

Nonrefrigerated Dry Storage Can Have Negative Effects on Postharvest Quality of Cut Lilium

Water uptake is a critical issue for postharvest physiology of cut flowers. After harvest, cut flowers lose access to water from roots and sometimes develop emboli inside the xylem, which can disrupt water uptake and undermine flower longevity. The duration of dry storage (desiccation) before flowers are placed in a vase may affect rehydration capability. Despite the appreciated importance of desiccation time on water balance, the duration of desiccation that might cause irreversible damage in Lilium sp. L. is unknown. Therefore, we investigated effects of pre-vase dehydration on water uptake and postharvest quality of cut lilies. Stems of Lilium ‘Nashville’, ‘Santander’, and ‘Sorbonne’ were subjected to 0, 8, 24, or 48 hours of dehydration at 20 °C, then rehydrated in a solution containing 2% sucrose and a biocide. Water uptake in the first 24 hours of rehydration was significantly greater in dehydrated stems than in control (0 hour) stems. Although dehydration treatments increased water uptake in the first 24 hours after rehydration, total water uptake in dehydrated stems over the ensuing 9- to 10-day vase period was significantly less than in controls. In the vase, 48 hours of dehydration reduced the total water uptake in ‘Nashville’ by 27% and in ‘Sorbonne’ by 48%. Individual flower life and stem vase life were not affected significantly by dehydration treatment; however, ‘Sorbonne’ stems dehydrated for 24 or 48 hours had smaller flowers than controls and those that underwent the 8-hour dehydration treatment. ‘Nashville’ stems dehydrated for 24 hours showed visible leaf yellowing 3 days earlier than controls; ‘Sorbonne’ dehydrated for 48 hours showed leaf yellowing 2 days earlier. We conclude cut lilies have an ability to recover partially from significant dehydration and can restore water uptake initially, but pre-vase dehydration reduces total water uptake and affects some postharvest attributes negatively.

Comprehensive Flavor Analysis of Volatile Components During the Vase Period of Cut Lily (Lilium spp. 'Manissa') Flowers by HS-SPME/GC-MS Combined With E-Nose Technology.

Volatile compounds could affect the flavor and ornamental quality of cut flowers, but the flavor change occurring during the vase period of the cut flower is unclear. To clarify the dynamic changes during the vase period of cut lily (Lilium spp. ‘Manissa’) flowers, comprehensive flavor profiles were characterized by the electronic nose (E-nose) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS). The response value of sensor W2W was significantly higher than other sensors, and its response value reached the highest on day 4. A total of 59 volatiles were detected in cut lilies by HS-SPME/GC-MS, mainly including aldehydes, alcohols, and esters. There were 19 volatiles with odor activity values (OAVs) greater than 1. Floral and fruity aromas were stronger, followed by a pungent scent. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) could effectively discriminate lily samples derived from different vase times on the basis of E-nose and HS-SPME-GC-MS. In summary, our study investigates the flavor change profile and the diversity of volatile compounds during the vase period of cut lilies, and lilies on day 4 after harvest exhibited excellent aroma and flavor taking into consideration of the flavor intensity and diversity. This provided theoretical guidance for the assessment of scent volatiles and flavor quality during the vase period of cut lily flowers and will be helpful for the application of cut lilies during the postharvest process.

Copper nanoparticles (CuNPs) increase the vase life of cut carnation and chrysanthemum flowers: antimicrobial ability and morphophysiological improvements

Abstract This research was carried out to evaluate the effects of copper nanoparticles (CuNPs) on the postharvest physiology of carnation and chrysanthemum cut flowers. Synthesized CuNPs were applied at 10 and 20 mg L-1 to both cut flowers by the pulsing method. The physicochemical characteristics and the activity of antioxidant enzymes were measured on 0, 3, 6 and 9 days along the vase life. According to heat map analysis, changes in measured parameters were affected by flower type > vase period > CuNPs concentration. Results also showed that treating the two species of cut flower with CuNPS by the pulse treatment improved the relative fresh weight (RFW), vase solution uptake (VSU), membrane stability index (MSI), flower diameter and total soluble carbohydrate (TSC). Meanwhile, a decrease in both bacterial population of the stem end and the hydrogen peroxide (H2O2) was observed. In comparison with the control, CuNPs at 20 mg L-1 by pulse treatment almost increased the vase life in both cut flowers by 30%.

Dry storage improves the vase quality of cut peony by increasing water uptake efficiency through aquaporins regulation

Proper storage prolongs peony market supply. Here, we determined the changes in fresh weight and expression of four aquaporin genes under dry storage (DS) and wet storage (WS). It has showed that after harvesting, the fresh weight change was accompanied with flower opening. After both short- and long-term of storage, the water uptake efficiency in DS group was greater during the first few vase days, providing a direct material basis of DS improved vase quality. The gene expression results showed that PlPIP1;3 and PlTIP2;1 were mainly expressed in petals, whereas PlNIP1;2-like and PlSIP2;1 were mainly expressed in the green tissues. In addition, the expression of PlTIP2;1 in the petals was consistent with the flower opening process, indicating that it may play a major role in facilitating water uptake. During cold storage, the expression of PlPIP1;3 and PlTIP2;1 was higher or more rapidly induced in the DS group, and thus we deduced that they play important roles in improving the vase quality of DS. Furthermore, the expression of PlNIP1;2-like in the early stage of the DS group was more stable than in WS, which may also be partially responsible for the vase quality improvement. In contrast, PlSIP2;1 may not be involved, since no significant change was observed between the DS and WS group. In short, the expression of PlPIP1;3 and PlTIP2;1 in the DS group during storage may improve water uptake efficiency during the vase period and then improving the vase quality of cut peony.

Evaluation of dry and wet storage on vase quality of cut peony based on the regulation of starch and sucrose metabolism

Herbaceous peony (Paeonia lactiflora Pall.) is one of the most important cut flowers worldwide, but the short natural florescence seriously affects its industrial development. In this study, the cut peony ‘Yang Fei Chu Yu’ was preserved in dry storage (DS) and wet storage (WS), respectively, at 0–4 °C. We set two treatments of short- and long-term storage (S-tS, 3 d; L-tS, 23 d). We assessed the postharvest performance; determined the changes in starch, sucrose, glucose, and fructose; and then analyzed the expression of a subset of representative genes that regulate starch and sucrose metabolism by RT-qPCR. When compared to WS, our results indicated that DS treatment exhibited significantly higher vase quality of cut peony after both S-tS and L-tS. For S-tS, this effect should be due to faster starch consumption during storage of 1–3 d and sucrose hydrolysis at the beginning of the vase period. The change in starch hydrolysis can be attributed to increased expression of PlSPS1 and PlSPS4 as well as decreased expression of PlSUS4, whereas the sucrose metabolism should be associated with the inducing of PlSUS3 expression. During S-tS, PlCWIN1 may positively and PlVIN1 may negatively affect vase quality by adjusting water use efficiency. Inducing expression of PlCIN1 and PlCIN2 may also improve cut flower quality, probably via other pathways. For L-tS, the higher level of glucose and fructose content at the end of the period may be more beneficial in improving vase quality. The increasing expression of PlSUS3 and the decreasing expression of PlVIN1 as well as the inducing expression of the three PlCINs may regulate this process at the transcriptional level. Based on these results, we recommend that DS is used for cut peony cold storage within a prescribed period, regardless of the storage time.

Effect of sodium dichloroisocyanurate and citrate phosphate buffer in vase solution on microbial growth and quality of Mokara orchid flowers ‘Moo-daeng’

Effect of sodium dichloroisocyanurate (DICA) and citrate phosphate buffer in vase solution on microbial growth and quality of Mokara orchid flowers (Arachins × Ascocentrum × Vanda) ‘Moo-daeng’ was investigated by holding flowers in citrate phosphate buffer (CPB) pH 5.4, citrate phosphate buffer pH 7.4, 50 ppm DICA + citric acid buffer pH 5.4 and 50 ppm DICA + citrate phosphate buffer (CPB) pH 7.4, respectively, in an observation room (21±2°C, 70-80% RH, cool-white fluorescence lights for 12 h d-1) throughout experimental period. The result showed that DICA + CPB was the most effective on inhibiting microbial growth in the vase solution. This was related to the microbial content in the xylem in day 0 and 6 by scanning electron microscopy (SEM). The microbial growth was undetectable in treatments of DICA + CPB while holding flowers in the buffer only had a load of microbial content in the xylem in day 6 of the vase period. Additionally, flowers hold in the buffer pH 7.4 produced the highest ethylene concentration and had the shortest vase life of 7.8 days, while the longevity of treatments of DICA + CPB pH 5.4 and 7.4 were 9.8 and 8.8 days, respectively.

Assessment of vase quality and transcriptional regulation of sucrose transporter and invertase genes in cut peony (Paeonia lactiflora ‘Yang Fei Chu Yu’) treated by exogenous sucrose

Cut peonies (Paeonia lactiflora Pall.) have become increasingly popular worldwide in recent years. However, the limited vase life and often poor vase quality have negatively affected the commercial development of this ornamental flower. In this study, 20 g L−1 sucrose was added to the vase solution of cut peony (‘Yang Fei Chu Yu’) to better understand the effect of sucrose on the vase quality. The results showed that sucrose treatment increased the number of days during which the flowers were fully opened by approximately 1.3 d, whereas treatment effects on the opening process were limited. Sucrose treatment delayed the decrease in flower fresh weight and sucrose concentration of the petals, while increasing glucose and fructose concentrations. Two sucrose transporter (SUT) genes, PlSUT1 and PlSUT2, and five invertase (INV) genes, PlCWIN1, PlVIN1, PlCIN1, PlCIN2 and PlCIN3, were isolated from a peony transcriptional database. Gene expression by RT-qPCR showed that both PlSUT2 and PlSUT4 were induced by sucrose treatment, indicating their putative role in transporting sucrose from the vase solution to the flowers. Among the five INVs, the expression of PlCWIN1 was greater in sucrose-treated flowers than in the controls from day 3 to the end of the vase period, indicating its possible role in increasing the number of days when the flowers were fully opened. The expression of PlVIN1 decreased in control flowers, but was delayed by sucrose treatment, especially on day 3. Since PlVIN1 was predicted to be located in the vacuole, it is highly possible that the expression of PlVIN1 helped to increase the vacuolar osmotic potential through the accumulation of glucose and fructose, thereby increasing water uptake for maintenance of flowers at the fully opened stage. Among the three PlCINs, the expression of PlCIN2 was much higher in sucrose-treated than in the control flowers throughout the vase period, indicating its major role in improving vase quality through sucrose treatment. Our study indicates that both SUTs and INVs are involved in maintaining the vase quality of cut peony flowers.

Alleviation of effects of exogenous ethylene on cut ‘Master’ carnation flowers with nano-silver and silver thiosulfate

Postharvest treatment with nano-silver (NS) extends the longevity of many cut flowers, including carnation (Dianthus caryophyllus L.). Its beneficial effects are generally attributed to the inhibition of bacterial growth in basal stem-ends. However, Ag+ ions released from NS are also potential blockers of ethylene action. In the present study, we investigated the efficacy of NS pulse treatment, compared with conventional silver thiosulfate (STS) treatment, for alleviation the effects of exogenous ethylene on cut standard ‘Master’ carnation flowers. Cut carnations exposed to 5 or 10 μL L−1 ethylene for 12 h showed reduced vase life, inhibited flower opening, premature wilting, and petal discoloration, which markedly diminished their ornamental quality. A NS pulse treatment of 250 mg L−1 (2.3 mmol L−1) for 1 h prior to ethylene exposure reduced the inhibited flower opening and, thereby, prolonged the vase life. These effects were comparatively inferior in terms of flower opening and vase life extension to those obtained with a 1.0 mmol L−1 STS pulse for 1 h. However, without exogenous ethylene NS treatment was nearly as effective as STS treatment for enhancing flower opening and extending vase life. NS treated cut carnation stems (exposed to exogenous ethylene or not) also maintained higher relative fresh weight during the vase period than those treated with STS. The Ag concentration in the stem-ends of the NS-treated cut carnations was higher than that in those of STS-treated stems, and was also higher than that in other tissues. Moreover, Ag provided by NS also reached the receptacles, calyxes, and petals. Overall, NS pulse treatments enhanced the ornamental quality and extending the vase life of cut ‘Master’ carnation flowers by antagonizing the deleterious effects of ethylene and probably inhibiting the proliferation of bacteria at the cut stem-ends.

Characterization of stomata on floral organs and scapes of cut ‘Real’ gerberas and their involvement in postharvest water loss

Stomata present on leaves are the main channels for water vapor exchange between the plant and atmosphere, and contribute to water loss of cut flowers. Although cut gerberas (Gerbera jamesonii Bolus) are commonly composed of a terminal composite floral head and a scape, and have no leaves, they are also prone to severe water deficits, presumably resulting from water loss exceeding water uptake. We have investigated the distribution and characteristics of stomata of cut ‘Real’ gerberas, and their response to light and abscisic acid (ABA) treatments, to increase understanding of their functionality in postharvest water loss. Stomata were widely distributed on various parts of floral organs and the scape in cut gerberas, including the lower epidermis of the ray floret petals, trans florets, disc florets, lower epidermis of sepals, and the uppermost and middle parts of scape surfaces. The highest stomatal density was observed on the lower epidermis of sepals. Cut gerberas had the largest stomata on the middle scape surface and the smallest on the surface of the uppermost scape. Nonetheless, the lower epidermis of sepals had the highest relative stomatal area, which was higher than that of the other parts. Additionally, the lower sepal epidermis had the highest maximum stomatal conductance of water vapor (gwmax), and which was higher than that of the lower and upper leaf epidermis. The opening of stomata on various parts of cut gerberas differed in their response to light, and the highest percentage of open stomata and largest aperture were found in the stomata on the lower epidermis of sepals. Changes in water loss in cut gerberas exhibited a distinct circadian rhythm over a four-day vase period with an alternating 12-h light/dark cycle. In the lower epidermis of sepals, ABA painting treatment significantly inhibited stomatal opening and reduced water loss in cut gerberas over a 6 h light period. These findings imply the critical involvement of stomata on the lower epidermis of sepals in water loss of cut gerberas, and improve our understanding of the mechanism underlying their water deficit symptoms.

Gel xylem occlusions decrease hydraulic conductance of cut Acacia holosericea foliage stems

The postharvest vase life of cut Acacia holosericea foliage stems is inherently short at 4–6 d. Stem and xylem specific hydraulic conductances (Khstem and Khxylem, respectively) were measured on alternate days over a 6 d vase period using 10cm long stem segments of cut A. holosericea foliage at four serial developmental maturity stages: viz., M1 – 25 to 35cm (most distal, juvenile), M2 – 15 to 25cm, M3 – 5 to 15cm, and M4 – cut end to 10cm (proximal, mature). Specific hydraulic conductance (Kh) was measured with de-ionised water (DIW), de-aerated de-ionised water (de-DIW), and 10mM potassium chloride (KCl) as perfusion solutions. Significant decreases in specific Khstem and Khxylem values were observed with increasing stem maturity from M1 to M4 and over time during vase life evaluation. Neither specific Khstem nor Khxylem was consistently improved with 10mM KCl as the perfusion solution. Stem segments were treated with ethylene as ethephon in Ethrel™ (4.8×10−5gL−1 or 4.8×10−4gL−1) and the ethylene binding inhibitor silver thiosulphate (STS; 2mM or 4mM). Physiological gel occlusion was observed microscopically and reduced solution flow in otherwise functional vessel lumens. This plugging was evidently the main cause of reduced specific Khstem and Khxylem across developmental maturity stages and over the time during the vase period. It was concluded that gel formation is an ethylene independent defensive wound healing mechanism in cut A. holosericea stems that reduces stem hydraulic conductance and explains their short vase life.

Nano-silver treatments reduced bacterial colonization and biofilm formation at the stem-ends of cut gladiolus ‘Eerde’ spikes

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 50mgL−1 for 24h 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 25mgL−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) mgL−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 50mgL−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 25mgL−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 24h at 35°C with 25mgL−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.

Salicylic acid and jasmonic acid treatments for potentially extending the longevity of cut Acacia holosericea foliage

ABSTRACTAcacia holosericea is a novel cut foliage line with a short vase life. Postharvest application of salicylic acid (SA) can extend the vase life of cut flower. SA is a host defence inducer, as is jasmonic acid (JA). SA and JA were compared as vase solution additives for A. holosericea. Three experiments were conducted that also compared these two chemicals with H+ and Cu2+ as known vase life extending additives. Vase solutions containing SA at 0.5, 1.5, and 2.5 mM gave ~1.3- to 1.5-fold vase life extensions as compared with the distilled water (DW; control). Provision of Cu2+ and JA at 0.5 mM in vase solutions also prolonged vase life by ~1.3-fold as compared with DW. The positive effect of SA tended to be greater than that of JA, but was inferior to that of Cu2+ at the same concentration. However, trend differences among these treatments were not statistically significant. Cut A. holosericea foliage stems treated with SA and JA exhibited higher relative fresh weight (RFW) and vase solution uptake rates as compared with DW. Overall, SA and JA evidently extended the vase life of cut A. holosericea foliage by inhibiting water loss and maintaining RFW during the vase period.

Biosynthesis of silver nanoparticles using Artemisia annua callus for inhibiting stem‐end bacteria in cut carnation flowers

A biological method for synthesising silver nanoparticles (AgNPs) was developed using the callus extracts from Artemisia annua L. under sunlight at 25,000 lx. The AgNPs were characterised using transmission electron microscopy, atomic force microscope, X-ray diffraction and Fourier transform infrared spectroscopy. The AgNPs were mostly spherical with the size of 2.1 to 45.2 nm (average 10.9 nm). Pulse treatments of AgNPs at 125, 250 and 500 mg/l for 1 h extended vase life of cut carnation (Dianthus caryophyllus cv. Green Land) flowers. Four dominant bacteria strains Arthrobacter arilaitensis, Kocuria sp., Staphylococcus equorum and Microbacterium oxydans were isolated from the stem-ends of cut D. caryophyllus flowers. AgNP pulse inhibited significantly bacterial growth in vase solution and cut stem ends during all of the vase period. The bacteria related blockage in the stem-ends was significantly alleviated by AgNP pulse because of its higher antibacterial efficacy against the dominant bacteria. In addition, ethylene release of cut carnation flowers was inhibited in response to AgNP pulse. This is the first time that the biologically synthesised AgNPs could be applied as a promising preservative agent for cut carnation flowers.

Pulsing With Low Concentration Gibberellin Plus Benzyladenine or Commercial Floral Preservatives Affect Postharvest Longevity, Quality, and Leaf Chlorosis of Cut Lilies and Gladioli

Effects of pulsing with different concentrations of gibberellin plus benzyladenine (GA4+7 + BA), a proprietary mixture of GA4+7 plus BA in a commercial floral preservative (GA4+7 + BA + preservative), or a propriety mixture of sugar plus acidifier developed for bulbous flowers (floral bulb preservative) were studied on postharvest performance and quality of cut lily (Lilium hybrids) and gladiolus (Gladiolus hybrids) flowers. Pulsing of cut stems of lily with GA4+7 + BA at 5 or 2 mL·L−1 GA4+7 + BA + preservative for 20 hours at 3 ± 1 °C extended the vase life and controlled leaf chlorosis of ‘Cobra’ oriental lily and ‘Cappuccino’ and ‘Dot Com’ asiatic lily. Cut ‘Orange Art’ asiatic lily performed best when pulsed with GA4+7 + BA at 10 mg·L−1. For cut gladiolus, pulsing with GA4+7 + BA at 10 mg·L−1 extended the vase life of ‘Alice’, ‘Mammoth’, and ‘Passion’, while ‘Scarlet’ had the longest vase life when pulsed with 5 mg·L−1 GA4+7 + BA. GA4+7 + BA + preservative also extended the vase life and controlled leaf chlorosis, but the floral bulb preservative had no effect on vase life extension or preventing leaf chlorosis of lilies. Gladiolus cultivars had no or minor leaf chlorosis during vase period. Overall, overnight pulsing with GA4+7 + BA or GA4+7 + BA + preservative extended the vase life and prevented leaf chlorosis and can be used by growers and wholesalers for maintaining quality of cut stems.