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  • Author or Editor: Jennifer Kalinowski x
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The cut flower industry needs postharvest techniques that allow for extended storage of fresh cut flowers to meet consumer demands. We compared the use of a sub-zero storage temperature (−0.6 °C) to maintain viable flowers with improved or comparable vase life to flowers stored at the industry standard (4 °C). The vase life of 17 commercially important cut flower species, alstroemeria (Alstroemeria), anemone (Anemone coronaria), campanula (Campanula medium), carnation (Dianthus caryophyllus), chrysanthemum (Chrysanthemum), delphinium (Delphinium elatum), freesia (Freesia), gerbera (Gerbera jamesonii), gypsophila (Gypsophila paniculata), larkspur (Consolida), lily (Lilium), lisianthus (Eustoma grandiflorum), ranunculus (Ranunculus asiaticus), rose (Rosa hybrida), stock (Matthiola incana), sunflower (Helianthus annuus), and tuberose (Polianthes tuberosa), when stored dry at −0.6 °C for durations of 4, 8, and 12 weeks was comparable to or longer than that when stored at 4 °C. Tuberose stems were not viable after holding for any storage duration or temperature. Experiment 2 compared the use of a prestorage pulsing treatment of water, hydrating solution, or holding solution containing carbohydrates for 8 hours before extended storage for carnation, chrysanthemum, delphinium, lily, and rose stems. Stems of carnation benefitted from pulsing with a hydrating solution and maintained vase life similar to that of nonstored control stems when stored for 4 weeks at −0.6 °C. Conversely, rose stems only maintained vase life similar to that of nonstored control stems when held at 4 °C for all pulsing solutions. Lily and chrysanthemum stems had a decline in vase life with all pulsing solutions and only remained viable after 8 weeks of storage when held at −0.6 °C. Additionally, stored chrysanthemum and lily stems had a longer vase life when stored at −0.6 °C than that when held at 4 °C after 4 and 8 weeks of storage, respectively, with all pulsing solutions. Delphinium stems were not viable after any storage duration. Experiment 3 further evaluated carnation, lily, and rose stems with and without a prestorage acclimation period at 4 °C for either 24 hours or 1 week before extended storage of 4, 6, or 8 weeks. Holding stems at 4 °C for 1 week before extended storage reduced the vase life of all species. Rose stems remained viable after 8 weeks of extended storage when held at −0.6 °C, but only when no prestorage hold was used. Lily and rose stems were not viable beyond 4-week storage durations when held at 4 °C, but they remained viable with no prestorage holding period after 8 weeks at −0.6 °C. Carnation stems maintained a longer vase life irrespective of a prestorage holding period when stored at −0.6 °C. Through this analysis, we showed that many species of cut flowers may be held at a sub-zero temperature with vase life better than or comparable to that with the industry standard of 4 °C.

Open Access

Growers have traditionally used mechanical pinching and other cultural practices to control height and encourage branching for full and uniform poinsettia (Euphorbia pulcherrima) plants. A total of six experiments were conducted over 5 years to evaluate the impact of chemically treating poinsettia on final height, branching, first color, visible bud formation, and anthesis. The first four experiments evaluated the potential of benzyladenine (BA) and gibberellins [GA(4+7)] to increase height of treated poinsettia. Timing of the application was assessed during Expt. 1 using a combined concentration of 3 ppm BA and 3 ppm GA(4+7) applied at 5, 7, 9, or 11 weeks after pinching; some cultivars exhibited significantly more elongated inflorescences when treatment occurred 7 or 9 weeks after pinching. The application method and frequency was assessed during Expt. 2, and treatments were applied one or three times with either drench application at a concentration of 2 ppm or foliar application at a concentration of 5 ppm or untreated controls. All plants treated with three drench applications produced taller plants on average than when only applied once or when treated with a foliar application. Expt. 3 further assessed height gain and effects on flowering during late-season production with foliar applications of BA+GA(4 + 7) applied 2 weeks after first color at a concentration of 2 ppm compared with untreated control plants. One cultivar, Mars Red, was observed to have a significant decrease in days to anthesis when treated (9 days) compared with untreated plants, but no cultivars exhibited a significant change in height resulting from treatment. Expt. 4 assessed both the application method (foliar and drench) and change in final environment when plants were either maintained in a greenhouse or relocated to a postharvest room before anthesis. Most cultivars experienced a significant height increase when treated with foliar application of BA+GA(4 + 7) regardless of the final environment, but a significant delay in days to first color, visible bud, and anthesis was prevalent, and only one cultivar exhibited a treatment benefit from drench application with no significant delay in flowering or differences caused by changing environment. Expts. 5 and 6 were conducted over 2 growing years to evaluate the benefits of chemically pinching poinsettia using dikegulac sodium at a concentration of 800 ppm applied either once or twice (1 week apart) or 1600 ppm applied once to promote branching. The tallest plants were those treated one time at a concentration of 800 ppm showing lack of dominance in the apical meristem. The greatest number of shoots occurred when plants were treated with 800 ppm twice, whereas one application of 800 or 1600 ppm often, but not always, resulted in more shoots compared with mechanically pinched plants. Interestingly, the increased number of shoots from treated plants was often more than double the number compared with mechanical pinching, but those additional shoots failed to develop, which resulted in only one or two additional inflorescences. Production time was found to be a tradeoff because most dikegulac sodium-treated plants experienced an increased number of days to first color, visible bud, and/or anthesis. These results demonstrate that height control, whether to encourage stem elongation or halt apical dominance, is cultivar-specific, and that although both the method and concentration may be determined uniformly on some cultivars, the timing of application is crucial because of potential delays in floral development.

Open Access

Six experiments were conducted using three cultivars to investigate the impact of water electrical conductivity (EC) and the addition of nutrients to vase solutions on postharvest quality of cut rose (Rosa hybrids) stems. Postharvest quality of cut ‘Freedom’ rose stems was evaluated using solutions containing either distilled water with sodium chloride (DW+NaCl) or DW+NaCl with the addition of a commercial floral preservative (holding solution containing carbohydrates and biocide) to generate a range of EC values (Expts. 1 and 2). The third experiment compared the effect of different EC levels from the salts NaCl, sodium sulfate (Na2SO4), and calcium chloride (CaCl2). The fourth experiment investigated EC’s impact on rose stems with the addition of two rose cultivars (Charlotte and Classy). When ‘Freedom’ stems were subjected to DW+NaCl, the longest vase life was achieved with 0.5 dS·m–1. The addition of holding solution not only extended vase life but also counteracted the negative effects of high EC with maximum vase life occurring at 1.0 dS·m–1. Furthermore, stems in the holding solution experienced significantly less bent neck and the flowers opened more fully than those in DW. Stems placed in DW with a holding solution also experienced more petal bluing, pigment loss, necrotic edges, and wilting than those held in DW alone. This effect was likely due to increased vase life. Salt solutions containing Na2SO4 and CaCl2 resulted in extended vase life at 1.0 dS·m–1, but increasing salt levels decreased overall vase life. As EC increased, regardless of salt type, water uptake also increased up to a maximum at 0.5 or 1.0 dS·m–1 and then continually declined. Maximum vase life was observed at 1.5 dS·m–1 for cut ‘Charlotte’ stems, and at 1.0 dS·m–1 for ‘Classy’ with the addition of a holding solution. Physiological effects were different based on cultivar, as observed with Charlotte and Freedom flowers that opened further and had less petal browning than Classy flowers. ‘Freedom’ had the greatest pigment loss, but this effect decreased with increasing EC. Further correlational analysis showed that in water-only solutions, initial and final EC accounted for 44% and 41% of the variation in vase life data, respectively, whereas initial pH accounted for 24% of variation. However, the presence of carbohydrates and biocides from the holding solution was found to have a greater effect on overall vase life compared with water pH or EC. Finally, in Expts. 5 and 6, cut ‘Freedom’ stems were subjected to DW solutions containing 0.1, 1, 10, or 100 mg·L–1 boron, copper, iron, potassium, magnesium, manganese, or zinc. None of these solutions increased vase life. Conversely, 10 or 100 mg·L–1 boron and 100 mg·L–1 copper solutions reduced vase life. Finally, the addition of NaCl to a maximum of 0.83 dS·m–1 increased the vase life in all solutions. These analyses highlight the importance of water quality and its elemental constituents on the vase life of cut rose stems and that the use of a holding solution can overcome the negative effects of high EC water.

Open Access