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The leaves of Zantedeschia and Hosta are used as florist greens in different floral arrangements. The most efficient postharvest treatment for cut foliage is the use of growth regulators, which prolong their vase life by delaying degradative changes occurring in leaves, especially proteolysis. Cycloheximide (CHI) is one of the protein synthesis inhibitors, blocking the enzymes responsible for decreasing membrane integrity, a phenomenon hastening senescence. The aim of this experiment was to evaluate the effects of CHI and benzyladenine (BA) or gibberellic acid (GA3) on the longevity of cut foliage in hosta (Hosta sp.) cultivars and Ethiopian calla (Zantedeschia aethiopica) and to follow the changes in certain proteolytic processes occurring during senescence. Generally, 24 h conditioning with cycloheximide shortened the longevity of cut calla leaves while having no effect on hosta vase life. In ageing leaves of ‘Minima Glauca’ hosta and calla, the total proteolytic activity increased, including that of cysteine protease. Due to the application of BA or GA3 in hosta and calla, respectively, this activity was limited. On the contrary, the use of CHI either did not affect the activity of cysteine protease or increased it several-fold relative to the control, in hosta and calla, respectively. Leaves treated with growth regulators had many more soluble proteins and fewer free amino acids, including free proline, than leaves from other treatments. The highest free proline level was determined in calla leaves conditioned with CHI, where it increased 18-fold relative to the initial level.

Cut lily flowers are very popular but their longevity is not satisfactory. The quality of cut lily flowers is determined by two factors: the longevity of the flowers and the general appearance of the entire cut stem during its vase life. The aim of this work was to evaluate the effects of gibberellic acid (GA3), standard preservative (8HQC and 2% sucrose) and commercial preservatives Chrysal Professional 2 and Chrysal sachet as well as Floralife 200 and Floralife 300 on the quality of ‘Rialto’ cut oriental lily, a white blooming cultivar very popular on the Polish market. The contents of reducing sugars, soluble proteins, free amino acids and free proline were also determined in the senescing flowers. As a major problem in the postharvest handling of lilies is leaf yellowing, the effects of postharvest treatments on the quality of leaves and their chlorophyll contents were also studied. Conditioning (24 h) with GA3 (500 mg d.m.−3) immediately after harvest delayed chlorophyll loss in leaves. When combined with the standard preservative and commercial preparations Chrysal Professional 2 and Chrysal sachet as well as Floralife 200 and Floralife 300, GA3 prolonged flower vase life. The most effective method was using GA3 and Floralife products, which prolonged the vase life of flowers to 23 days, 43% longer relative to the untreated flowers, and maintained the decorative value of the leaves (53 days). During the senescence of flowers held in water, the contents of reducing sugars, free amino acids and proline increased. However, the holding solutions modified changes in these parameters relative to the control.

We report on the effect of holding solutions containing 8-hydroxychinoline (8-HQC) and sucrose (2-10%) on senescence parameters in three daffodil cultivars. Xylem blockages obstructing water uptake in many flowers did not develop in cut daffodil scapes. The use of preservatives improved hydration of perianth but did not result in longer vase life. Only with 'Golden Harvest' was the corona longevity prolonged following application of the biocide with 6% and 10% sucrose. Changes in the structure of epidermis cells occurred after harvest: corona epidermis was more durable than that of perianth, which may account for shorter longevity of the latter element. The use of 8-HQC with 2% sucrose positively affected epidermis structure in the corona and perianth. Individual floral structures differed in their ability to accumulate sugars delivered in the preservative and translocated within the flower. Generally, supplementing flowers with exogenous sucrose results in ovary growth and not in an increased perianth longevity. However, a higher sugar content was found not only in the ovary but also in the corona of flowers held in the preservatives and this may explain a longer longevity of that floral structure as compared to perianth. [ABSTRACT FROM AUTHOR]

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]

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Treatments with BA or GA3 are known to extend the foliage display life of Hosta ‘Undulata Erromena’ and Zantedeschia aethiopica Spr., respectively. The effects of a 24hrs pulse conditioning with BA or GA3 on the protein content, proteolytic activity and the expression of the cysteine protease gene were studied in senescing cut leaves of both species. A decrease in the soluble protein content in the untreated leaves was accompanied by an increased total proteolytic activity and the activity of the cysteine protease. The BA treatment in Hosta prevented such increases thereby preventing total protein loss. In Z. aethiopica, the GA3 treatment delayed protein degradation but to a lesser extent than the BA treament of H. ‘Undulata Erromena’ leaves. No expression of the cysteine protease gene was observed in the freshly cut leaves of both species. The presence of the gene transcript was detectable in the senescing leaves of both species kept in water where significant increase in the cysteine protease activity was observed. No increase in the level of the cysteine protease mRNA was detected in the BA - conditioned leaves of Hosta but a slight increase in the transcript level was observed in Z. aethiopica regardless of whether the leaves were conditioned with GA3 or were kept in water. Different reaction of the two species for two plant growth regulators inhibiting senescence suggest different mechanism of this process. [ABSTRACT FROM AUTHOR]

During the vase life of cut stems obstruction of xylem vessels occurs due to microbial growth, formation of tyloses, deposition of materials in the lumen of xylem vessels and the presence of air emboli in the vascular system. Such obstructions may restrict water uptake and its transport towards upwards thus lowering their ornamental value and longevity of cut flowers. Clematis is a very attractive plant material which may be used as cut flower in floral compositions. Nothing is known about the histochemical or cytological nature of xylem blockages occurring in cut stems of this plant. This study shows that in clematis, tyloses are the main source of occlusions, although bacteria and some amorphic substances may also appear inside the vessels. A preservative composed of 200 mg dm(-3) 8-HQC (8-hydroxyquinolin citrate) and 2% sucrose arrested bacterial development and the growth of tyloses. This information can be helpful in the development of new treatments to improve keeping qualities of cut clematis stems.