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Clematis is a new species grown as cut flower, whose vase life is variable and cultivar-depended. Little is known about senescence of its cut flowers and their response to flower preservatives. The aim of the study was to evaluate the effect of a preservative (standard preservative SP, 8-hydroxyquinoline citrate plus sucrose) or a biocide solution (8-HQC) on certain senescence-related processes in cut clematis flowers. Analyses were done immediately after harvest and at the end of the vase life when control flowers held in water were wilting. A possible relationship between senescence parameters and the vase life of clematis taxa was also sought. As in most cut flowers, the contents of reducing sugars and soluble proteins in clematis petals decreased during the vase life while the proteolytic activity, including that of the cysteine protease, increased and was accompanied by accumulation of free proline and ammonium. Cut flower longevity in cultivars under study was not associated with the initial levels of reducing sugars, soluble proteins or free proline. Neither was the initial proteolytic activity or its increase during vase life related to the vase life itself: cultivars having comparable life spans differed dramatically in the initial and final proteolytic activities. Both solutions containing 8-HQC significantly affected the senescence-related processes and flowers held in them had more soluble proteins and lower proteolytic activity (total, and that of the cysteine protease) than control flowers held in water. Approximately a twofold increase in reducing sugars was observed in flowers held in SP relative to those held in water or in 8-HQC while the accumulation of free proline and ammonium was limited in their petals. This suggests a regulating action of exogenous sugar in senescence of clematis flowers. However, the delay of senescence produced by the preservative was not always associated with a longer vase life in any given cultivar. Further studies are needed to elucidate the role of sugar in clematis flower senescence. [ABSTRACT FROM AUTHOR]

Clematis is visually a very attractive plant which can be used for cut flowers, provided that proper cultivars are chosen. In this study, the phenomenon of programmed cell death (PCD) was compared in petals of clematis blooming on mother plants in the open field and in cut flowers, in two cultivars with different flower longevity. The dynamics of PCD in petals of field grown plants in the two cultivars were different. In the long flower longevity cultivar the first symptoms of PCD were observed in the flower bud, and in the open flower the process was already advanced. On the other hand, PCD in petals of the short flower longevity cultivar was advanced already in the flower bud. In both cultivars the nuclear degradation started early, but the dynamics were different: in the long flower longevity cultivar 18.6% of the nuclei were degraded in the open flower vs . 68.3% of degraded nuclei already in the flower bud in the short flower longevity cultivar. Senescence processes are intensified in cut flowers. In cut flowers of both cultivars kept in water the process of DNA degradation was much faster than in flowers growing on mother plants. It could be slowed down by the addition of preservatives. The standard preservative of 8-hydroxyquinoline citrate (8-HQC) 200 mg L −1 with 2% sucrose prolonged the vase life of cut flowers of both cultivars as compared to water, but organelle degradation in petals was delayed only in the shorter-lived cultivar. [ABSTRACT FROM AUTHOR]

Short vase life of cut lilac stems limits its commercial potential. Rapid wilting of cut lilac inflorescences is probably caused by blockage of water transport in stems. The purpose of this study was to recognize the nature of the occlusions blocking xylem vessels in cut stems of common lilac and to identify a relationship, if any, between the type of a holding solution, xylem blockages and vase life of lilacs flowering under different environmental conditions. The stems of the white flowering cultivar “Mme Florent Stepman” were harvested in Nov/Dec from shrubs forced from the beginning of November by a standard procedure involving treatment with 37 °C, in January from shrubs forced from the beginning of November under 15 °C, and in May from control shrubs, i.e., flowering naturally in the field. Cut stems were placed in distilled water, 8-HQC, a standard preservative composed of 8-HQC + 2% sucrose, nanosilver and nanosilver + 2% sucrose. Tyloses were observed in stem xylem vessels while practically no microorganisms were detectable. The incidence of blockage formation in the stems depended on the flowering date and the biocide used. The longest vase life was observed in January with 8-HQC or 8-HQC + S, but in all flowering periods the least xylem blockages were formed when NS was used as the biocide. Therefore, formation of tyloses does not appear to be directly related to the postharvest life of lilac and its vase life can be extended by standard florists’ preservatives irrespective of their effect of the xylem physical obstructions. [ABSTRACT FROM AUTHOR]

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Lisianthus is among the most popular cut flowers. Regarding the postharvest losses, these experiments were designed to compare the effects of a nanosilver (NS) based preservative to the standard preservative containing 8-hydroxyquinoline citrate (8-HQC) and sucrose (S). Additionally, the effect of 24 h conditioning in the NS solution on the postharvest longevity and the general condition of lisianthus (Eustoma grandiflorum 'Mariachi Blue') was tested. The vase life of flowers on conditioned and non-conditioned stems was extended by the preservatives, more so by NS + S than by 8-HQC + S (44–54% versus 13–23%). Conditioning had no detectable effect on longevity. Daily water uptake showed alternative peaks and drops, with a general tendency of the uptake rate to decrease over time. The highest uptake intensity and the highest transpiration rate were in stems in the NS + S solution while the lowest was in 8-HQC + S. Conditioning negatively affected the average fresh weight of the flowering stems in all holding solutions with stems in preservatives being heavier than those in water. Preservatives did not induce accumulation of the total soluble or reducing sugars in petals; such accumulation was promoted by conditioning, but only in the upper flowers. The free proline content increased in senescing lower flowers on non-conditioned stems; conditioning limited this increase in flowers in preservatives. In the upper flowers, free proline increased in both water controls while the preservatives and conditioning generally reduced the proline contents below the initial level. Conditioning lowered the hydrogen peroxide contents in senescing lower flowers, relative to the initial level and the non-conditioned stems. The catalase activity kept dropping during the vase life in both the lower and upper flowers, in conditioned and non-conditioned stems, with the exception of flowers from water where the activity remained the highest from all three treatments. It appears that the NS preservative with sucrose improves the overall condition of lisianthus flowers and extends their vase life. [ABSTRACT FROM AUTHOR]

Recently peonies have become very popular cut flowers. As peony flowering period is short, long term cold storage could assure its prolonged supply and make long distance transport feasible. The effect of dry cold storage, of 8-hydroxyquinoline and nanosilver preservatives on the peony keeping qualities were tested on the most popular cultivar 'Sarah Bernhardt'. The 12 week storage (0–1 °C) shortened flower longevity by 20%, to 8 days and no vascular blockages in the shoots were observed. However, the presence of callose, not considered as a blocking factor, was evident. The sucrose-containing preservatives with either 8-hydroxyquinoline or nanosilver did not extend the flower longevity but they increased flower diameters in both fresh and stored material. Generally, the soluble total and reducing sugars increased in senescing flowers in both non-stored and stored flowers, and they were lower after storage. The free proline increased ca. 20-times during cold storage and at the end of the vase life it remained generally higher in the stored than in fresh flowers. The level of hydrogen peroxide dropped after 12 weeks storage and its contents at the end of the vase life differed depending on the holding solution. Generally it was lower after storage. Storage increased the catalase activity which remained on higher levels in stored flowers from all holding solutions as compared to freshly cut flowers. A five-fold reduction in the peroxidase activity occurred during storage but its activities at the end of the vase life were similar in stored and non-stored flowers. The effects of nanosilver and 8-hydroxyquinoline were similar. [ABSTRACT FROM AUTHOR]

Peony is one of the most important ornamental plants in the international flower market, but has a relatively short vase life in water. This study tested the effects of 8-hydroxyquinoline citrate (8-HQC) and nanosilver (NS) in combination with sucrose, as well as two commercial preservatives, on the longevity and some physiological and biochemical aspects of senescence of cut flowers of 14 cultivars. Responses varied both by cultivar and treatment. The preservatives extended the vase life in only five cultivars; however, in nine cultivars, preservatives increased the flower diameter and improved the general flower appearance. Blockages in xylem vessels started to appear soon after harvest. Both NS and 8-HQC with sucrose prevented tylose formation, while bacterial blockages were reduced only by the NS solution. Reduction in stem blockages did not translate into better water balance or flower longevity. The highest carbohydrate accumulation in petals was observed in the NS solution. Preservatives mitigated the rise in free amino acids, including free proline. They did not prevent an increase in H2O2 content but flowers in preservatives generally had higher catalase activity than in the control. As solutions with NS produced comparable or even better results than 8-HQC, we recommend the latter as a component of a preservative for cut peony flowers. However, cultivar-specific responses indicate that postharvest treatments must be individually tailored to each cultivar. [ABSTRACT FROM AUTHOR]

• A combination of nanosilver with sucrose extends the vase life of snapdragon flowers. • It prevents tylose formation but not the blockages caused by bacteria. • It increases the activities of antioxidative enzymes. • It delays the nuclei and epidermis degradation. • NS itself limits increases in the EC and pH of the cell sap. Snapdragon (Antirrhinum majus L.) is one of the most important annuals grown for cut flowers, but its vase life in water is relatively short. In this study, the effects of nanosilver (NS) on the vase life of cut snapdragon and effects on physiology, biochemical and morphology levels were investigated. Xylem vessel blockages started to appear soon after harvest. NS prevented tylose formation, but not the blockages caused by bacteria. Cut flowers treated with 1 mg L−1 NS with 2 % sucrose had a longer vase life than those held in water or in NS alone, and improved flower opening, coloration and higher relative water content of flowers in the lower (older) part of the spike. Carbohydrate accumulated in flowers in the NS solution. NS limited increased electric conductivity, and with sucrose decreased the pH of cell sap. NS also limited the increase in the malondialdehyde content, especially in the upper (younger) part of spikes where also the hydrogen peroxide content was much lower than in flowers from the lower spike parts. The activities of antioxidative enzymes were higher in the NS-treated flowers, especially when the NS solution was supplemented with sucrose, and the nuclei and epidermis degradation was delayed. It is evident that the presence of NS in the holding solution, especially when supplemented with sucrose, delays and reduces the severity of all senescence symptoms, thereby extending the useful vase life of snapdragon. [ABSTRACT FROM AUTHOR]