We have investigated the patterns of ethylene biosynthesis in carnation (Dianthus caryophyllus L.) genotypes that exhibit extended vase life in comparison to flowers of White Sim'. `White Sim' flowers exhibited typical symptoms of senescence, including petal in-rolling and rapid wilting, beginning 5 days after harvest. In contrast, the other genotypes studied did not show petal in-rolling or rapid wilting associated with petal senescence. The first visible symptom of senescence in these flowers was necrosis of the petal tips, and it occurred from 3 to 7 days after the initial symptoms of senescence were seen in `White Sim' flowers. In all cases, the extended-vase-life genotypes did not exhibit the dramatic increase in ethylene production that typically accompanies petal senescence in carnation. This appeared to be the result of limited accumulation of ACC. In addition, flowers of these genotypes had limited capacity to convert ACC to ethylene. Therefore, we conclude that the low level of ethylene produced by these flowers during postharvest aging is the result of low activities of both ACC synthase and the ethylene-forming enzyme. Treatment of `White Sim' flowers at anthesis with 1.0 μl ethylene/liter resulted in the induction of increased ethylene biosynthesis and premature petal senescence. The extended-vase-life genotypes exhibited varying responses to ethylene treatment. One genotype (87-37G-2) produced elevated ethylene and senesced prematurely, as did flowers of `White Sim'. A second genotype (82-1) was induced to senesce by ethylene treatment but did not produce increased ethylene. A third genotype (799) was unaffected by ethylene treatment. The results of this study suggest these extended-vase-life genotypes are representative of genetic differences in the capacity to synthesize and respond to ethylene. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).
Amanda S. Brandt and William R. Woodson
Rik van Gorsel, A. Verlind, A. van de Wiel, and G. van Leeuwen
Low root zone temperatures in summer stimulate generative development of Alstroemeria, resulting in a higher flower production in winter. The effects of greenhouse soil and air temperatures on vase life and ornamental value were evaluated. Preharvest treatments were two locations (field stations), four air temperatures (9, 12, 15, 18C), four root zone temperatures (11, 14, 17C, uncontrolled) and three varieties ('Flamengo', 'Jubilee', 'Wilhelmina') in a factorial design. The flowers were placed in a commercial pretreatment solution for 24 hours immediately after harvest. After a two day transport simulation and rehydration for 3 hours at 5C, flowers were kept at 1.5 W.m-2 PAR (12hr/day), 20C and 60% RH. The experiment was done three times. Results from the first harvest showed that lowering the soil temperature increased the number of stems that had two whirls of flowers opening after harvest. Average vase life was two weeks. Low air temperatures increased whirl opening as well, and increased vase life by one or two days. Ornamental value and number of flower branches per stem were not affected.
Claudine Ménard and Blanche Dansereau
The general objective of this project was to study the impact of preharvest growth conditions [supplementary lighting as high-pressure sodium (HPS) or metal halide (MH) lights, and fertilization] on the postharvest quality of greenhouse roses. On 25 Jan. 1991, 288 plants (Rosa × hybrida `Royalty', `After-Glow', and `Obsession') of 3× caliber were planted in pots. A split-split plot experimental design made up of four blocks was used. Light treatments (three) were main plots while fertilization (two) and cultivars (three cultivars; four plants per cultivar) were subplots and sub-sub-plots, respectively. The two fertilization regimes used had respective N: K (in ppm) ratios of 150 N: 300 K (F1) and 300 N: 300 K (F2). Three light treatments [ambient light conditions (control) and ambient light conditions + PPF of 100 μmol·m-2·s-1 supplied by 400-W HPS or MH lamps] were compared. Yields were significantly affected by supplemental light treatments, fertilization, or both regardless of cultivars. Results indicate that stems harvested from HPS and MH light treatments combined with fertilization F1 had a longer vase life than those grown with F2. HPS lamps significantly increased vase life compared to MH. The level of abscisic acid (ABA) was higher under MH than under HPS lamps at time zero (T0), and this was similar for all cultivars. Furthermore, when supplemental light was combined with the F1 fertilization, a lower ABA level was obtained. Low ABA levels were correlated to longer vase life expectancy.
Rodney B. Jones, Margrethe Serek, Chen-Lan Kuo, and Michael S. Reid
Petal opening and senescence of cut Gladiolus, Iris, and Narcissus flowers was significantly inhibited by continuous treatment with 1 mm CHI. Vase life was doubled in individual flowers treated when half-open, and a similar effect was detected after pulsing cut gladiolus spikes with 1 mm CHI for 24 hours. Petal wilting was markedly inhibited in flowers treated with CHI and was confined to the outer 2 to 3 mm of petal margins as opposed to the entire petal in untreated flowers. These effects were not seen, however, in CHI-treated cut tulip flowers, where vase life was significantly reduced. CHI markedly inhibited protein synthesis in Gladiolus `New Rose' florets (a decrease of >60%). Treatment with a potent biocide, DICA, did not increase vase life; therefore, CHI was not prolonging flower longevity by preventing microbial growth in the vase solution. The results indicate that de novo protein synthesis is required for bulb flower development and opening and petal wilting and senescence. Chemical names used: cycloheximide (CHI), sodium dichloroisocyanuric acid (DICA).
Mario Valenzuela-Vazquez and Geno A. Picchioni
Lupinus havardii (Big Bend bluebonnet) is a winter annual plant indigenous to the semiarid southwestern U.S. with potential to become a new cut flower commodity. Nothing is presently known about the mineral nutrition of bluebonnet in greenhouse conditions, either in the whole plant or its short-lived cut racemes, and its possible relationship with vase life longevity. At first appearance of floral buds, supplemental Ca treatments (0, 2.5, 5.0, and 10.0 mm Ca using CaCl2) were added to the nutrient solution over a 2-month growing period, to evaluate the influence of Ca on plant nutrient allocation patterns, nutrient uptake and utilization, and raceme physiology after cutting. Ca supplementation increased net Ca uptake per plant by 40%, 77%, and 95% over the control (2.5, 5.0, and 10.0 mm Ca, respectively; P < 0.05). The increased Ca uptake per plant increased Ca concentration in racemes (a weak Ca sink), which resulted in marginal increases in vase life duration (1 day). This positive influence on vase life duration was not significant due to limited number of raceme replicates. When plants were supplemented with 5 mm Ca, the net accumulation of Ca, P, K, and Mg in roots increased by 4 to 5 times over the control roots. These increases occurred in parallel to an increase in root dry matter production. Similar patterns were observed in the net accumulation of Ca, P, K, and Mg per plant. In our conditions, Ca supplementation (5 mm) enriched raceme Ca concentration as well as whole-plant consumption of Ca, P, K, and Mg in bluebonnet plants. These data will be useful in developing fertilization strategies for this new and promising greenhouse floral crop.
Claudine Menard, Blanche Dansereau, and Yves Desiardins
The general objective of this project is to study the impact of pre-harvest growth conditions (supplementary lighting; HPS, MH: fertilization on the biochemistry and post-harvest quality of greenhouse roses. On January 25, 1991, 288 plants (Rosa × hybrida: `Royalty', `After Glow' and `Obsession') 3X caliber were planted in pots. A split-split plot experimental design made up of four blocks was used. Light treatments (3) were in main plot while fertilization (2) and cultivars (3 cultivars; 4 plants per cultivar) were in sub-plots and sub-sub-plots respectively. The two fertilization regimes used had respectively a nitrogen potassium ratio of 150N:300K ppm (F1) and 300N:300K ppm (F2). Three light treatments (ambient light conditions (control), and ambient light conditions + PPF of 100 μmolm-2 s-1 supplied by 400 W HPS and MH lamps) were compared. Since the beginning of this experiment 14 431 flowering stems have been harvested. Only the results obtained with `Royalty' and `After Glow' will be presented for the following harvest periods; (1) October 6 to December 6, 1991; (2) January 30 to April 22, 1992. Yields were significantly affected by light and/or fertilization regardless of cultivar. Preliminary results indicate that stems harvested from HPS and MH light treatments combined to fertilization regime F1 had a longer vase life than those grown with F2. Preliminary results indicate that HPS lamps significantly increased vase life compared to MH. The level of ABA was higher under MH then under HPS lamps at to and this was similar for all cultivars. Furthermore, when supplemental light was combined to the F1 fertilization a lower level of ABA was obtained. Low levels of ABA are correlated to longer vase life expectancy.
Mike Schnelle and Julia Whitworth
Woody cut-flower plots were planted in Mar 1994 in Lane, Okla. Eight species with 10 replications each were chosen for their potential variety of fresh-cut stems and foliage, fruit, and flowers. Not only were the woody species planted for demonstrative purposes at field days and workshops, but they also were used for harvest and analysis of their vase life. Local florists also were exposed to new potential species and queried for their initial impression of the plants' aesthetic qualities and their likelihood of acceptance by the florists' patrons.
Andrew J. Macnish, David H. Simons, Daryl C. Joyce, John D. Faragher, and Peter J. Hofman
Postharvest longevity of some cut flowers is shortened by exposure to ethylene gas. Adverse effects of ethylene may be prevented by treatment with 1-methylcyclopropene (1-MCP) gas. Responses of 14 different native Australian cut flowers to 1-MCP and ethylene applied at concentrations of 10 nL·L-1 and 10 μL·L-1, respectively, were examined. Each gas was applied alone for 12 hours at 20 °C and they were also applied in series. Vase lives of Ceratopetalum gummiferum, Chamelaucium uncinatum, Grevillea `Kay Williams' and `Misty Pink', Leptospermum petersonii, Telopea `Shady Lady', and Verticordia nitens were reduced by ethylene treatment. Treatment with 1-MCP generally protected these cut flowers against subsequent exposure to ethylene. The 1-MCP treatment usually did not extend their vase lives in the absence of exogenous ethylene.
Andrew J. Macnish, Ria T. Leonard, and Terril A. Nell
The postharvest longevity of fresh-cut flowers is often limited by the accumulation of bacteria in vase water and flower stems. Aqueous chlorine dioxide is a strong biocide with potential application for sanitizing cut flower solutions. We evaluated the potential of chlorine dioxide to prevent the build-up of bacteria in vase water and extend the longevity of cut Matthiola incana `Ruby Red', Gypsophila paniculata `Crystal' and Gerbera jamesonii `Monarch' flowers. Fresh-cut flower stems were placed into sterile vases containing deionized water and either 0.0 or 2 μL·L–1 chlorine dioxide. Flower vase life was then judged at 21 ± 0.5 °C and 40% to 60% relative humidity. Inclusion of 2 μL·L–1 chlorine dioxide in vase water extended the longevity of Matthiola, Gypsophila and Gerbera flowers by 2.2, 3.5, and 3.4 days, respectively, relative to control flowers (i.e., 0 μL·L–1). Treatment with 2 μL·L–1 chlorine dioxide reduced the build-up of aerobic bacteria in vase water for 6 to 9 days of vase life. For example, addition of 2 μL·L–1 chlorine dioxide to Gerbera vase water reduced the number of bacteria that grew by 2.4- to 2.8-fold, as compared to control flower water. These results confirm the practical value of chlorine dioxide treatments to reduce the accumulation of bacteria in vase water and extend the display life of cut flowers.
Young A. Kim and Jong Suk Lee
To investigate the differences of anatomical structure of neck tissue between bent-neck and strong-neck flowers, scanning electron microscopy of neck tissue during senescence of cut rose flowers held in deionized water or preservative solution (3% sucrose + 200 ppm HQS + 0.1 mM ethionine) was observed. Lignins in xylem, phloem, and interfascicular cambium of neck were stained to red by phloroglucine. More lignin was formed in the phloem of neck in rose flowers held in preservative solution than deionized water. Neck strength of cut rose could be increased by increase of lignin content, and this would prevent bent-neck and extend vase life. Parenchyma cells in neck part of rose flowers held in deionized water had thinner cell wall and less starch grains at senescence than those of flowers held in preservative solution at day 7. These starch grains would be used as energy source of rose flowers and extend vase life. Globular crystals were observed in the inner part of cells and had shape of large thorny. These crystals were cumulated in cell walls, then would prevent the activity of cell wall decomposition or increase cell wall permeability.