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  • Author or Editor: Francis J. Marousky x
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Abstract

Loss of turgor, or moisture depletion, in cut flowers contributes to deterioration. Chemically fortified flower preservatives have been shown to maintain turgor and prolong cut flower life. However, the mechanism by which floral preservatives reduce moisture stress and prevent deterioration is elusive. If physiological responses could be related to preservative components we might be able to explain deterioration and to isolate its causal factors.

Open Access

Abstract

A review of our work on water relations summarized findings that showed the complexity of cut-flower deterioration (19). In tests with the preservative combination 8-hydroxyquinoline citrate plus sucrose (8 HQC + S), and its individual components some of the factors responsible for deterioration were separated and explained. Most of that review concerned bud-cut roses but, in general, was applicable to chrysanthemums and other cut flowers. Reports of our work on bud-cut chrysanthemums, started in 1967 (19), supply additional background material (13, 15, 16, 20). Information has also been contributed in other studies (4,10).

Open Access

Abstract

Freshly harvested roses, Rosa hybrida ‘Better Times’, held in acid (pH 3) solutions had longer life than flowers held in less acid (pH 5-7) solutions. Increased flower longevity was due to inhibition of vascular blockage and increased water absorption in acid solutions. Increase in water absorption produced an increase in fresh weight. Sucrose supressed water absorption. Although sucrose-treated roses absorbed less solution, they gained more weight than roses held in water. Increase in fresh weight was apparently caused by stomatal closure and increased moisture retention induced by sucrose. Eight-hydroxyquinoline citrate reduced the incidence of vascular blockage and increased water absorption and flower longevity. Eight-hydroxyquinoline citrate was more effective in reducing vascular blockage in a solution at pH 4 than at pH 6. The role of 8-hydroxyquinoline citrate in inhibiting vascular blockage cannot be wholly ascribed to pH effects.

Open Access

Abstract

The efficacy of 8-hydroxy-quinoline citrate in prolonging the life of cut roses was due to decreased vascular blockage in stems, increased water absorption, and stomatal closure. Sucrose increased the respiratory rate of rose petals but 8-hydroxy-quinoline citrate did not influence respiration. Sucrose also prolonged life of cut roses by reducing stomatal opening but water absorption was reduced. A solution of 200 ppm 8-hy-droxyquinoline citrate and 3% sucrose improved longevity of cut roses by reducing moisture stress through increased water absorption and retention. Roses held in this solution lasted twice as long as roses held in water.

Open Access

Abstract

The influence of temperature and various scarification treatments on the physical changes of the lemma and germination of bahiagrass (Paspalum notatum Flugge) were studied. Mechanically scarified seeds readily germinated on an agar medium. Acid-scarified seeds germinated better than untreated seeds, but not as readily as mechanically scarified seeds. All caryopses excised from nongerminated acid-scarified seeds readily germinated on an agar medium after 17 days. Excised caryopses were placed on a temperature gradient bar corresponding to positions at 15.5°, 21°, 26.5°, 32°, and 37.5°C. All caryopses germinated at 21° to 37.5°, but germination and seedling growth were best at 32° to 37.5°. Lipase and acid scarification improved germination when seeds were held at 24°, but did not enhance germination when seeds were held at 32°. Scanning electron microscopy revealed that acid scarification removed the cuticular substances of the lemma and the substances in the fissure of the germinating lid, probably facilitating entrance of the water and earlier emergence of the coleorhiza. The data suggest that the lemma and palea are physical barriers in bahiagrass.

Open Access

Premature deterioration and/or wilting of cut flowers such as roses (“bent neck”) has been attributed to vascular blockage within the cut stem. Vascular blockage has been attributed to both the proliferation of bacteria in the cut flower water and/or to products exuded by the stem. Separation of these causative agents is prevented by the inability to obtain intact microbe-free flowers. With the objective to produce microbe-free flowers, 36 miniature rose cultivars were screened for their capacity to flower in vitro. Stem segments containing single lateral buds were surface sterilized in 1.05% (v/v) sodium hypochlorite and rinsed three times in sterile distilled deionized water. Buds were established on medium consisting of Murashige and Skoog mineral salts, Woody Plant Medium organics, 3.0% (w/v) sucrose, 0.5 mg/liter benzyladenine, 0.1 mg/liter indole-3-acetic acid, and 50 mg/liter each citric and ascorbic acids. Medium was solidified with 1.5 g/liter gelrite and 4 g/liter TC® agar. Of the 36 cultivars screened, eight (22%) grew poorly in vitro. Of the 28 responsive cultivars, 14 (50%) produced flower buds in vitro However, only six cultivars produced open flowers in vitro.

Free access

A broad source of Gerbera × hybrida Hort. germplasm was evaluated for vase life. Senescence mode, i.e., bending or folding of stems or wilting of ligulae was also recorded for flowers evaluated. Intensive selection was practiced to improve vase life. About 10% of the plants from a sample population were selected for having flowers with high vase life. Progeny means for vase life resulting from a topcross between these plants and `Appleblossom' were used to select five plants (about 1.5% of the sample population) whose flowers had high vase life. A diallel cross using these five plants as parents resulted in a progeny population with an increase in mean vase life of 3.4 days compared to mean vase life for the initial sample population. Increases in vase life means for days to bending, folding, and wilting were 0.3, 3.5, and 1.2 days, respectively. Plants with flowers which senesced due to wilting had the longest mean vase life before and after breeding. Changes in proportion of senescence modes were observed; bending decreased, folding and wilting increased. Frequencies of bending, folding, and wilting were compared to vase life means for 10 progenies. Proportion of bending generally decreased as vase life increased.

Free access