Effects of CaCl2 solutions to alleviate drought stress effects in potted ornamentals Salvia splendens and Ageratum houstonianum

Bedding plants are often subjected to soil water deficit – either after planting and/or during the market chain. Methods to alleviate the negative water stress effects are sought for to preserve ornamental values of plants. The aim of this study was to evaluate the response of two bedding plants, Ageratum houstonianum Mill. and Salvia splendens Sellow ex Scult., to water stress and treatments with calcium chloride aimed to alleviate drought effects. Plants were subjected either to 45 days of periodical stress (five cycles when watering was off for 5 consecutive days, followed by four cycles on for 5 consecutive days) or 10 days of radical drought (complete water withdrawal). On the first day, before the onset of drought, plants were watered with 0.5% Ca or 1% Ca w/v as a solution of calcium chloride (5 g or 10 g Ca per 1 dm3 of the growing substrate). The similarly Ca-treated but routinely watered plants provided controls to evaluate the water shortage effects. Plant height, inflorescence length/number, leaf number, leaf area (in Salvia splendens only), aboveground plant part weight, and root weight (in Salvia splendens only) as well as leaf relative water content (RWC) were measured at the beginning and at the end of the experiments. Water withdrawal during 10 days of growth (radical drought) reduced by half RWC in leaves of withering Salvia splendens and Ageratum houstonianum plants. Its effects on the growth parameters were less pronounced and mitigated by Ca applications. Also in the periodically stressed plants of both species, RWC and most growth parameters were reduced by water shortage but Ca applications alleviated the negative stress effects

The Effect of a Sugar-Containing Preservative on Senescence-Related Processes in Cut Clematis Flowers

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

Flowering conditions affect flower longevity in Syringa vulgaris and cause changes in protein content, protease activity and expression of a KDEL-CysEP gene

Forcing is a method that is usually used to induce flowering in plants, independent of the natural blooming period. The temperatures required to start blooming in lilac in November are ca. 37°C causing degeneration of flowers. Forcing at 15 °C in November requires 49 days to bloom as compared to 23 days for the standard 37 °C, but gives panicles of much better quality than those forced by standard method (37 °C). In this study, we have investigated the protein content, total protease activity, and cysteine protease activity at different stages of flowering (flower bud whitening and swelling, open flowers, wilted flowers) for lilac flowers (Syringa vulgaris L., fam. Oleaceae) blooming under three different conditions: natural conditions in May and forcing in a greenhouse in November at 37 °C (standard forcing) or at 15 °C (alternative forcing). The protein content was relatively constant during flowering for each of the three sets of conditions. Flowers from 15 °C had a significantly lower total protease and cysteine endoprotease activity than flowers from 37 °C at all stages. Flowers from plants blooming in May had a very time-specific cysteine protease activity, which was dramatically higher for the open flower stage than for the other stages. The partial coding sequence for a KDEL-CysEP was isolated, and its expression was determined by qRT-PCR. The gene expression did not correlate with the cysteine endoprotease activity especially in May natural flowering and November alternative forcing at 15 °C. Alternative forcing method at 15 °C affected the flowering process delaying senescence, presumably due to the low cysteine protease activity. © 2016, The Author(s).National Center of Knowledge (NCN

Mechanical Stimulation Decreases Auxin and Gibberellic Acid Synthesis but Does Not Affect Auxin Transport in Axillary Buds; It Also Stimulates Peroxidase Activity in Petunia × atkinsiana

Thigmomorphogenesis (or mechanical stimulation-MS) is a term created by Jaffe and means plant response to natural stimuli such as the blow of the wind, strong rain, or touch, resulting in a decrease in length and an increase of branching as well as an increase in the activity of axillary buds. MS is very well known in plant morphology, but physiological processes controlling plant growth are not well discovered yet. In the current study, we tried to find an answer to the question if MS truly may affect auxin synthesis or transport in the early stage of plant growth, and which physiological factors may be responsible for growth arrest in petunia. According to the results of current research, we noticed that MS affects plant growth but does not block auxin transport from the apical bud. MS arrests IAA and GA3 synthesis in MS-treated plants over the longer term. The main factor responsible for the thickening of cell walls and the same strengthening of vascular tissues and growth arrestment, in this case, is peroxidase (POX) activity, but special attention should be also paid to AGPs as signaling molecules which also are directly involved in growth regulation as well as in cell wall modifications

Effects of CaCl2 solutions to alleviate drought stress effects in potted ornamentals Salvia splendens and Ageratum houstonianum

Bedding plants are often subjected to soil water deficit – either after planting and/or during the market chain. Methods to alleviate the negative water stress effects are sought for to preserve ornamental values of plants. The aim of this study was to evaluate the response of two bedding plants, Ageratum houstonianum Mill. and Salvia splendens Sellow ex Scult., to water stress and treatments with calcium chloride aimed to alleviate drought effects. Plants were subjected either to 45 days of periodical stress (five cycles when watering was off for 5 consecutive days, followed by four cycles on for 5 consecutive days) or 10 days of radical drought (complete water withdrawal). On the first day, before the onset of drought, plants were watered with 0.5% Ca or 1% Ca w/v as a solution of calcium chloride (5 g or 10 g Ca per 1 dm3 of the growing substrate). The similarly Ca-treated but routinely watered plants provided controls to evaluate the water shortage effects. Plant height, inflorescence length/number, leaf number, leaf area (in Salvia splendens only), aboveground plant part weight, and root weight (in Salvia splendens only) as well as leaf relative water content (RWC) were measured at the beginning and at the end of the experiments. Water withdrawal during 10 days of growth (radical drought) reduced by half RWC in leaves of withering Salvia splendens and Ageratum houstonianum plants. Its effects on the growth parameters were less pronounced and mitigated by Ca applications. Also in the periodically stressed plants of both species, RWC and most growth parameters were reduced by water shortage but Ca applications alleviated the negative stress effects

Effect of postharvest treatments on the longevity of cut inflorescences of ‘Rialto’ oriental lily

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

Characterization of interspecific hybrids of <i>Petunia</i> and <i>Calibrachoa</i> by multiplex PCR, DNA content, and chromosome number

<p><i>Petunia</i> and <i>Calibrachoa</i> are ornamental plants of worldwide economic importance. Commercially, it is useful to combine desirable characteristics of <i>Calibrachoa</i>, including the large diversity of flower colors, with the pH tolerance and vigorous growth of <i>Petunia</i>. For investigation of interspecific hybrids between <i>Petunia</i> and <i>Calibrachoa</i> we used four different introns with flanking exon areas, each from a different gene and with a different sequence for <i>Petunia</i> and <i>Calibrachoa</i>, as genus-specific markers for chromosomes in interspecific hybrids. PCR primers specific for <i>Petunia</i> and <i>Calabrachoa</i> were made from the determined sequences and tested on a range of presumed hybrids using multiplex PCR, which confirmed that the hybrids were derived from these two species. Flow cytometry demonstrated that the hybrids were triploid, and determination of chromosome numbers showed that two of the chromosome sets were from <i>Calibrachoa</i>, i.e. that the other parent, <i>Petunia</i>, was diploid. Similar methods can be used for molecular characterization of other new hybrids made between closely related species or cultivars.</p

Postharvest Treatments Improve Quality of Cut Peony Flowers

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

The effect of cycloheximide and growth regulators on the senescence of cut leaves in Hosta sp. and Zantedeschia aethiopica

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