Prolonging Vase Life Research Articles

Physiological characteristics and vase life responses of rose cut flowers (Rosa hybrida L. cv. ‘Royal Baccara’) to benzyl adenine and 1- metylcylcopropene

+prolonging vase life and decreasing post-harvest losses are considered a basic strategy towards sustainable development of agriculture, and the application of growth regulators, e.g. benzyl adenine(BA) and 1-metylcylcopropane(1-MCP), is one of the practical methods for them. The effects of benzyl adenine(BA) and 1-metylcylcopropene(1-MCP) on some biochemical characteristics and vase life of rose cv. ‘Royal Baccara’ (Rosa hybrida L. cv. ‘Royal Baccara’), were explored in a factorial experiment based on a randomized complete block design with three replications in 2017. The factors included BA at three levels of 0 (control), 75 and 150 ppm and 1-MCP in three levels of 0 (control), 1 and 2 µl/L-1. The results showed that the maximum soluble protein content was observed in 150 (ppm) BA+ 2 (µl.L-1) 1-MCP treatments on the second, fourth, sixth, and eighth days. The results of this research revealed that BA at the rates of 75 and 150 ppm and 1-MCP at the rates of 1 and 2 (µl.L-1) enhanced soluble protein content by 10.49, 13.37, 15.18, and 18.18 percent as compared to the control, respectively. The results showed that the maximum proline content was related to the control and the minimum content was observed in the plants treated with 150 (ppm) BA+ 2 (µl.L-1) 1-MCP. The endoproteases enzyme content was slightly decreased on the eighth day, indicating the efficacy of BA and 1-MCP in inhibiting the senescence process and prolonging vase life of rose flowers. The results showed that the application of 1 or 2 μl.L-1 1-MCP and 150 mg L-1 BA can improve the vase life of cut roses

EFFECT OF ESSENTIAL OILS ON STORAGE AND KEEPING QUALITY OF GLADIOLUS CUT FLOWERS

A trial was consummated at Postharvest Lab. of Floriculture Res. Dept. Hort. Res. Inst. ARC, Giza, Egypt during 2019 and 2020 seasons to study the influence of essential oils of clove and sage oil in two experiments as preservative solutions, or a spray treatments as well as under long term of storage at low temperatures for three periods on quality and vase life of cut inflorescences of Gladiolus grandiflorus. In the first experiment five holding solutions included, clove oil at 1 and 2 mg/l + 20 g/l sucrose (suc.), sage oil at 1and 2 mg/l + 20 g/l sucrose (suc.), 8-hydroxyquinoline citrate (8-HQC) at 200 pm + 20 g/l sucrose (suc.) and control (distilled water D.W.) were used. In second experiment that used essential oils as spray treatments. The obtained results from the two experiments indicated that, the flowers hold in the preservative solution of sucrose + clove oil (1 mg/l) significantly prolonged vase life, increased flowers fresh weight (%) and water uptake (g), dry weight (%), percentage of opening floret (%) and decreased water loss(g), bacterial counts in the vase solution. Essential oils had a positive effect on total sugar concentrations, level of total indoles and total phenols and total chlorophyll contents of cut flowers. Essential oils as an alternative substitute to chemical compounds had an excellent effect on cut flowers also because of their antimicrobial activities and environmental friendly nature.

Changes in carbohydrates associated with senescence of cut gladiolus spikes under pulsing and wet cold storage durations

Several biochemical and metabolic changes are associated with senescence of cut gladioli, particularly in relation to quality characteristics, including dynamism of carbohydrates. The objective of this study was to evaluate the effect of pulsing and wet cold storage on the starch and sugar biomarkers on cut Gladiolus (Gladiolus grandiflorus L. cv. Fado) vase quality. Pulsing treatments of 600-ppm 8-hydroxyquinoline sulphate, plus 5% sucrose solution, versus distilled water, were administered prior to wet cold storage durations of 0 - 5 days, on the cut Gladiolus grown from corms. This was done in the open field at the Horticulture Research and Teaching Field, Egerton University in Kenya, during two successive seasons. There was a significant difference (P <0.01) in total soluble sugars (TSS) and total starch of spikes pulsed with 600 ppm 8 - HQS + 5% sucrose, compared with the control, during the third day in the vase life of the cut flowers. Prolonged vase life of cut spikes was associated with a decrease in total soluble sugars and increase in total starch, as influenced by pulsing and wet storage duration up to 4 days.

Changes in carbohydrates associated with senescence of cut gladiolus spikes under pulsing and wet cold storage durations

Several biochemical and metabolic changes are associated with senescence of cut gladioli, particularly in relation to quality characteristics, including dynamism of carbohydrates. The objective of this study was to evaluate the effect of pulsing and wet cold storage on the starch and sugar biomarkers on cut Gladiolus (Gladiolus grandiflorus L. cv. Fado) vase quality. Pulsing treatments of 600-ppm 8-hydroxyquinoline sulphate, plus 5% sucrose solution, versus distilled water, were administered prior to wet cold storage durations of 0 - 5 days, on the cut Gladiolus grown from corms. This was done in the open field at the Horticulture Research and Teaching Field, Egerton University in Kenya, during two successive seasons. There was a significant difference (P &lt;0.01) in total soluble sugars (TSS) and total starch of spikes pulsed with 600 ppm 8 - HQS + 5% sucrose, compared with the control, during the third day in the vase life of the cut flowers. Prolonged vase life of cut spikes was associated with a decrease in total soluble sugars and increase in total starch, as influenced by pulsing and wet storage duration up to 4 days.

Nanosilver as a novel biocide for control of senescence in garden cosmos

To prolong their vase life, cut flowers are commonly kept in holding solutions. These must include a biocide to retard bacterial growth. In this study, the effect of nanosilver (NS) on certain aspects of senescence in cut garden cosmos (Cosmos bipinnatus) flowers was compared to that of the commonly used 8-hydroxyquinoline citrate (8-HQC). In combination with sucrose, both biocides prolonged cosmos vase life but did not prevent the occurrence of stem blockages. NS was more effective in limiting a reduction in endogenous soluble carbohydrates. The malondialdehyde (MDA) contents increased in senescing ray florets, both in intact and control cut flowers held in water. Both biocides were comparably effective in limiting this effect. The hydrogen peroxide content tripled in intact flowers but dropped in flowers held in water or the 8-HQC solutions; in flowers kept in NS solutions its increase was moderate. Also, the catalase activity increased in intact flowers but dropped in all cut flowers. Both biocides had similar effects on the enzyme activity, in both pure solutions and with sucrose. Most of these parameters were not significantly correlated with vase life. Overall, the effect of nanosilver on senescence in cut cosmos flowers was similar to that of 8-HQC.

1-methylcyclopropene prolongs the vase life of roses cv. Osiana

The objective of this study was to determine the effect of 1-methylcyclopropene (1-MCP) on vase life of rose cv. Osiana in different storage conditions and in the presence of exogenous ethylene. The roses were treated with 0.5; 1.0; 1.5 and 2.0 g m-3 of Ethylbloc?, and submitted to the following conditions: Storage at 5 °C with stems in water; Storage at 22 °C with stems in water; Storage at 5 °C in ‘Strong’ type paper for 3 days and subsequent storage at 22 °C. The best storage condition was at 22 °C with the stems in the water. Doses greater than 1.0 g m-3 of Ethylbloc? prolonged vase life. In this condition, the stems were treated with 1.0 g m-³ Ethylbloc?; 1.0 g m-3 Ethylbloc? + 10 ?L L-1 ethylene and 10 ?L L-1 ethylene for 24 h. The Ethylbloc? increased vase life even in the presence of ethylene and fresh mass on the first two days. It reduced ethylene production by flowers in the first 24 h, and respiratory activity after 36 h. It can be concluded that the concentration of 1.0 g m-3 of Ethylbloc? prolongs the vase life of cv. Osiana stored at room temperature with the stems in water even in the presence of exogenous ethylene.

Lanthanum Prolongs Vase Life of Cut Tulip Flowers by Increasing Water Consumption and Concentrations of Sugars, Proteins and Chlorophylls

We evaluated the effect of separately adding two sources of lanthanum (La), LaCl3 and La(NO3)3 × 6H2O at a concentration of 40 µM each, to the preservative solution of 15 cut tulip flower varieties. Ascorbic acid (AsA; 0.2 g/L) was used as a reference solution, while distilled water was used as control. The variety Laura Fygi recorded the longest vase life with 13 days. The highest water consumption per gram of stem fresh biomass weight (FBW) (2.5 mL) was observed in the variety Violet Beauty, whereas the lowest (1.098 mL) was recorded in Pink Impression. At the end of the vase life period, higher concentrations of total soluble sugars in petals and total soluble proteins in leaves were recorded in La-treated stems, compared to the AsA treatment and the control. Additionally, La(NO3)3 × 6H2O supply increased the fresh weight of stems in vase and prolonged vase life. Moreover, this treatment resulted in the highest foliar concentration of chlorophylls at the end of vase life. Therefore, La increases tulip flower vase life as a consequence of improving the concentrations of some vital biomolecules.

Correlation Between Vase Life and Biochemical Parameters in Ornamental Sunflower (Helianthus annuus L.) Affected by Spraying Chemical Materials During the Growth Stages

The study was conducted to investigate the correlation between vase life and biochemical parameters in sunflower. The experiment was arranged in a randomized complete block design with five replications. Plants were sprayed by 50/100 mg L−1 salicylic acid, 50/100 mg L−1 thiamine, 100/200 mg L−1 ascorbic acid, and distilled water as control group at the eight-leaf stage. After one month, the spray treatments were repeated. The effects of preharvest spray treatment on vase life, protein, lipid peroxidation, peroxidase, polyphenol oxidase, and catalase were investigated. The result showed that thiamine by the most prolonged vase life was the most effective treatment at 50 mg L−1 with 25 days. Its vase life was more than twice the vase life of the control treatment. Also, the application of both concentrations of salicylic acid, ascorbic acid, and thiamine increased the amount of protein content, catalase, and peroxidase activity, and decreased polyphenol oxidase activity and lipid peroxidation among petals and leaves. Besides, while the vase life exhibited a positive correlation with peroxidase, catalase, and protein activity, it showed a negative correlation with polyphenol oxidase and lipid peroxidation.

Methyl Jasmonate Treatment Delays Flower Opening and Petal Wilting of Three Cut Rose Cultivars

Abstract Developing a method for the control of cut flower opening and improvement of cut flower quality is important to meet consumer demand. In this study, we investigated the effects of methyl jasmonate (MeJA) on flower opening of three rose cultivars: ‘Red Star,’ ‘Princes Meg,’ and ‘Madrid’. Shoot bases of cut roses were immersed in water solutions containing 100- or 1000-μM MeJA in addition to 2% weight/volume (w/v) sucrose and 0.02% w/v 8-hydroxyquinoline monohydrate. Subsequently, the vase life, flower opening, petal wilting, petal weight, water uptake, and water evaporation were measured. Flower opening of all three cultivars was clearly delayed following the treatment with MeJA, resulting in prolonged vase life compared with control. In addition, flower wilting was suppressed in all cultivars. Moreover, 7 days following treatment, the petal fresh weight was maintained high in the ‘Red Star’ and ‘Princes Meg’ cultivars. However, there was no significant difference in the ‘Madrid’ cultivar versus control. In all three cultivars, there was a minimal difference in the total amount of water uptake and evaporation. Thus, it is suggested that the total amount of water uptake and evaporation have limited relevance to the changes in the relative fresh weight of cut roses and petal fresh weight observed following treatments. Despite the difference in the sensitivity of the rose cultivars to treatment with MeJA, we conclude that MeJA has high potential as a quality retention agent for cut roses.

The transgenic Dendrobium ‘Sonia’ BOM 17 containing an antisense ACO gene demonstrated normal growth with prolonged vase life

The transgenic <i>Dendrobium</i> ‘Sonia’ BOM 17 containing an antisense <i>ACO</i> gene demonstrated normal growth with prolonged vase life

Benzyladenine and gibberellic acid pulses improve flower quality and extend vase life of cut dahlias

A 24-h pulse of cut dahlias in a solution containing both benzyladenine and gibberellic acid at 10–20 mg L−1 improved flower quality after 4 d in the vase and prolonged vase life regardless of handling method (dry packed or held in water from harvest through delivery).

Evaluation of Piper betle mediated silver nanoparticle in post-harvest physiology in relation to vase life of cut spike of Gladiolus

BackgroundThe purpose of this study is to evaluate the effect of green synthesized silver nanoparticles on post-harvest physiology of cut flower in relation to improvement of its vase life as well as keeping quality of the flowers taking gladiolus cut spikes as a model.ResultsThe synthesized Piper betle mediated silver nanoparticles (PbSNPs) were characterized by using UV-visible spectroscopy and transmission electron microscopy studies. It was revealed that PbSNPs ranges from 30 to 50 nm in diameter and spherical in shape. The experiments were conducted to study the effect of PbSNPs on post-harvest physiology, vascular blockage, prolonging vase life, and keeping the quality of cut spike of gladiolus. The treatment consisted of six vase solutions, viz. distilled water (control), 4% sucrose (T1), 4% sucrose + 100 ppm 5-SSA (T2), 4% sucrose + 2 ppm PbSNPs (T3), 4% sucrose + 4 ppm PbSNPs (T4), and 4% sucrose + 6 ppm PbSNPs (T5). Experimental outcomes depicted that T4 vase solution gives the best results in all the aspects statistically compared to its positive control (T2). The results also show PbSNPs in vase solution might have played a significant role for scavenging the reactive oxygen species by inducing antioxidant enzyme system at the time of senescence, leading to a decrease in lipid peroxidation and increase in the membrane stability.ConclusionsThis study revealed that application of T4 vase solution helps to maintain spikes fresh and dry weight, reduce the vascular blockage, improve the antioxidative defense, and stabilize the membrane integrity that leads to delay senescence.

Pre-harvest ethylene control affects vase life of cut rose ‘Carola’ by regulating energy metabolism and antioxidant enzyme activity

We studied the role of ethylene control in regulating energy metabolism, antioxidant enzyme activity, and vase life of cut rose Rosa hybrida ‘Carola’. Rose flowers at stage II were sprayed with one of the following solutions: water (control), 10 μL L−1 1-methylcyclopropene (1-MCP), or 0.5 g L−1 2-chloroethanephosphonic acid (ethephon). After harvest, ethylene production rate, respiration intensity, energy charge (EC), activities of energy metabolism-related and antioxidant enzymes, and malondialdehyde (MDA) content were measured. Results showed that 1-MCP enhanced the activities of superoxide dismutase, H+-adenosine triphosphatase, Ca2+-adenosine triphosphatase, succinic dehydrogenase, and cytochrome c oxidase, increased adenosine triphosphate (ATP) content, maintained high EC levels, inhibited respiration intensity, reduced peroxidase (POD) and polyphenol oxidase (PPO) activity and MDA accumulation, and prolonged vase life. Ethephon promoted ethylene production and respiration intensity, increased POD and PPO activity, reduced ATP content and EC levels, and accelerated senescence. Our results support a novel role for ethylene control in regulating senescence of ‘Carola’.

Endogenous hydrogen gas delays petal senescence and extends the vase life of lisianthus cut flowers

Exogenous hydrogen-rich water (HRW) improves vase life and quality of cut flowers, but the effects of endogenous hydrogen gas (H2) are not known. During the vase of cut lisianthus flowers, endogenous H2 concentrations decreased and redox homeostasis was impaired. The supplementation with HRW containing 0.078 mmol L−1 H2 blocked, but 2,6-dichlorophenolindophenol (DCPIP; a putative inhibitor of H2 synthesis) increased, endogenous H2 production. Senescence of cut flowers was delayed by H2, but accelerated by DCPIP. Also, decreased vase life by DCPIP was blocked by H2 administration. These beneficial roles of H2 were associated with less lipid peroxidation, and the increased activities of superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, and catalase. Compared with DCPIP alone, the soluble protein, total chlorophyll, and proline contents were elevated when H2 and DCPIP were added together. Overall, endogenous H2 prolongs vase life of lisianthus cut flowers in part by maintaining redox homeostasis.

Biochemical, physiological changes and antioxidant responses of cut gladiolus flower 'White Prosperity' induced by nitric oxide

Sodium nitroprusside (SNP), as nitric oxide (NO) donor, has been considered by postharvest researchers as one of the best option for slowing the processes controlling senescence in cut flowers. Here, we investigate the role of NO on postharvest physiology and vase life of the Gladiolus grandiflorus cv. White Prosperity. Vase life markedly extended by SNP at 150 μM from 3 day to 7.33 day and thus those inducer effects were dose- and time-dependent. SNP at 125 μM interdependent on vase life time period was observed to be the optimal dose for improving of relative fresh weight (RFW), peroxidase (POD), and total monomeric anthocyanin (TMA) in cut flowers. Supplementing vase solution with SNP indicated significant increase in water uptake of cut flowers and consequently protected to decline in RFW due to alleviate water losses stress. SNP was maintained the level of total soluble protein, lipid peroxidation, and POD, whereas it enhanced the level of catalase (CAT) and TMA in flower petals. Summary of our results revealed that SNP exogenous prolongs vase life via maintaining protein degrade, scavenging free radical in term of anthocyanin and enzymes antioxidant, decreasing polyphenol oxidase, inhibiting lipid peroxidation, and improving membrane stability in ‘White Prosperity’ cut flowers.

The combination of EthylBloc Sachet and 2,4-pyridinedicarboxylic acid reduces petal blackening and prolongs vase life of cut flowers of lotus (Nelumbo nucifera Gaerth) cvs. Sattabongkot and Saddhabutra

Abstract Postharvest lotus (Nelumbo nucifera cvs. Sattabongkot and Saddhabutra) flowers show a rapid petal blackening which shortens the vase life of flowers. We studied the effect of EthylBloc Sachet and/or 2,4-pyridinedicarboxylic acid (PDCA) on the petal blackening and the vase life of two commercial cultivars. Cut flowers were treated with distilled water (control), EthylBloc 2 Sachet (active ingredient 0.014%, fumigation for 6 h at 256 ppb), vase solution of 2,4-PDCA (2.0 mM) or the combination of EthylBloc Sachet and 2,4-PDCA. All treatments were kept at 28 ± 1 °C and 80–85% RH. The combination of 2,4-PDCA and EthylBloc Sachet caused the longest vase lives of 49.8 h with ‘Sattabongkot’ and 69.0 h with ‘Saddhabutra’, when the control values were 44.4 and 36.0 h, respectively. The combination of EthylBloc Sachet and 2,4-PDCA increased water uptake, delayed weight decrease and hue angle change, and reduced petal blackening. Moreover, the treatment caused less ethylene production and less respiration in the flowers than the other treatments. This method is useful for handling in commercial cut lotus flower.

The effects of 24-epibrassinolide corm priming and foliar spray on morphological, biochemical, and postharvest traits of sword lily

Gladiolus, or sword lily, is one of the most important cut flowers worldwide. Enhancement of its traits is of paramount importance to the flower industry. The application of 24-epibrassinolide (EBR) by corm priming and plant foliar spray to improve morphological, biochemical and postharvest characteristics of Gladiolus grandiflorus cv. Oscar were investigated. Concentrations of 0.5, 1, and 2 µM EBR as well as distillated water as a control were used for both corm priming and foliar spray treatments. Results showed that the highest levels of corm sprouting and flower spike emergence were obtained at 1 µM EBR. Floret numbers, flower spike fresh and dry weight, and vase life showed the highest values at 1 µM EBR combined treatments. The combination of corm priming at 2 µM and foliar spay at 1 µM EBR, showed the highest effect on malondialdehyde reduction. The highest activities of antioxidant enzymes such as catalase, peroxidase, and superoxide dismutase were obtained in combination of 1 µM EBR corm priming and 1 µM EBR foliar spray. EBR treatments prolonged vase life from 8 to 14 days and significantly improved gladiolus morphological and biochemical traits.

Pulsing Preservatives to Prolong Vase Life of Cut Rose Flowers in Bahir Dar, Northwestern Ethiopia

The longevity of cut flowers including cut roses can be however prolonged using different pulsing preservatives where researches in this regard are lacking in the country. Keeping these bottlenecks of the sector in mind, this study was therefore initiated with objective to evaluate the effectiveness of different pulsing preservatives in prolonging vase life of cut rose varieties. The experiment was conducted at Tana Flora PLC in Bahir Dar, Ethiopia. As pulsing preservatives Al2(SO4)3)(250 mg-1), Ca(ClO)2 (66.7 mg-1), STS [Ag (S2O3)2] (0.5 ml-1), Sugar (20 g-1) and distilled water were used. The three rose varieties namely: Upper class, Athena and Moon walk were used. Healthy flower buds having uniform length and harvested early in the morning were put immediately in containers filled with the respective concentration of pulsing preservatives. Flasks with six rose flowers each were placed in pre-cooling room (8-10 OC) for about 2 hours. Finally, treated cuttings were transferred into experimental room with temperature of 22-250C and 75% relative humidity and arranged in Complete Randomized Design (CRD) with three replications. At this time, pulsing preservatives were replaced by distilled water. The analysis of variance revealed that most of parameters were highly significantly influenced by the main as well as interaction effects of pulsing preservative and varieties (P&lt;0.0). Maximum water uptake (7.73 g/flower/day), transpiration loss (7.08 g/flower/day), flower fresh weight (21.77 g/flowers), flower head diameter (7.6 cm), and maximum flower vase life (23 days) were recorded in Athena variety pulsed with STS.

Combination Effect of 1-Methylcyclopropene (1-MCP) with Ajowan Essential Oil and Silver Nanoparticles on Postharvest Life of Gerbera (Gerbera jamesonii) Cut Flowers

Gerbera (Gerbera jamesonii Bolus ex. Hook f.) is one of the most important cut flowers in floriculture industry with high economic value. Short postharvest life is the main barrier for gerbera marketing which is related to water relation disruption resulting from microbial population in preservative solution and exposure to ethylene. Therefore, an experiment was conducted to study the combination effect of an ethylene inhibitor, 1-methylcyclopropene (1-MCP) (0 and 1 μL·L−1), and two antimicrobial agents, ajowan [Carum copticum (L.) C. B. Clarke] essential oil (EO) (0 and 15 μL·L−1) and silver nanoparticles (AgNPs) (0 and 40 μL·L−1), on postharvest life of ‘Pink Power’ gerbera cut flowers. The results showed that stem diameter reduced in both cut stem-end (CSE) and below the flower head (BFH) but the amount of decrease in CSE was more than BFH, and applied treatments had no significant effect on the decrease rate. However, both ajowan EO and AgNPs treatments reduced the number of bacteria at the CSE; ajowan EO was more effective than AgNPs and induced more vase solution uptake. Stem-end electrolyte leakage (EL) was unaffected by 1-MCP treatment, whereas petal EL was lower in 1-MCP-treated flowers. The least wilting percentage and the longest vase life were observed in combination treatment of 1-MCP and either ajowan EO or AgNPs. It could be concluded that 1-MCP combined with ajowan EO or AgNPs, potentially can be used as a preservative solution to enhance postharvest life, delay flower senescence, and prolong vase life of gerbera cut flowers.

Growing conditions and preservatives affect longevity, soluble protein, H2O2 and MDA contents, activity of antioxidant enzymes and DNA degradation in cut lilacs

Abstract Common lilac ( Syringa vulgaris L.) is a popular ornamental shrub which under natural conditions of the temperate zone blooms for ca three weeks in May. Forcing procedures may extend the flowering period to 6 months in autumn and winter. Temperatures required to begin the forcing cycle range from 37 °C in November to 16 °C in March. Forcing lilac at 15 °C in November is also effective but longer than in the standard method, used by most growers. This study compared vase life and certain senescence-related processes in cut flowers of common lilac harvested from shrubs flowering under different conditions, i.e. outdoors under ambient temperature, forced in a greenhouse under 37 °C (the standard method) or 15 °C (the alternative method), and held in water or two vase solutions containing either nanosilver (NS) or 8-hydroxiquinoline citrate (8-HQC) as biocides and supplemented with 2% sucrose. The highest influence on vase life of cut lilacs had growing conditions. The vase life of cut lilacs obtained by the alternative forcing method – regardless of a holding solution – was significantly higher than those obtained by the standard forcing or blooming naturally. The highest H 2 O 2 content and proteolytic activity were usually observed in flowers collected from stems held in water. MDA content varied depending on flowering conditions and holding solutions. Its relatively low content was observed in the alternatively forced lilacs held in both preservatives which also prolonged the vase life relative to water, decreased the H 2 O 2 content and delayed nuclei degradation in petals. The activity of chosen antioxidant enzymes varied depending on the flowering conditions and generally remained unaffected by the preservatives. The effects of nanosilver with sucrose on cut lilac senescence were comparable to the action of the standard preservative containing 8-HQC, therefore this solution may also be recommended as an efficient preservative delaying senescence and prolonging vase life of cut lilacs.