Cleanliness and Care: Providing Practical Solutions to Increase Fresh Cut Flowers
Cleanliness and Care: Providing Practical Solutions to Increase Fresh Cut Flowers, Dr. Terril Nell, University of Florida, $51,000, 3 year project
Research Update - January 2006
Terril A. Nell, Andrew J. Macnish and Ria T. Leonard
Department of Environmental Horticulture, University of Florida, Gainesville FL 32611
Project Overview for 2005
Proper cleanliness and care is imperative to maximize the postharvest life and quality of fresh cut flowers, but it remains a critical challenge facing the floral industry. In this project, we are developing practices and evaluating products that improve quality and longevity and implementing procedures that aim to reduce microbial contamination and water stress of flower stems. Specifically, we are focusing the research on the following areas:
- Evaluating grower, wholesale and retail procedures to prevent leaf yellowing and extend longevity of cut flowers.
- Evaluating procedures to increase water uptake and reduce water stress.
- Developing effective sanitation techniques that maximize flower longevity.
- Identify best care and best practices that maximize flower longevity and quality.
Our goal is to develop industry-friendly procedures to increase flower longevity and quality. We are exercising great care not to duplicate the research efforts of other researchers. As we progress with this research project, one of our greatest difficulties has been obtaining domestically- and internationally-grown flowers for the research.
Terril and Andrew will be going to Colombia in January 2006 and several other times in 2006 to conduct on-farm treatments. We anticipate trips to California for on-farm level treatments but will wait to confirm some results seen in the Colombian trials.
Experiments Completed in 2005:
Leaf Yellowing
· Testing postharvest treatments to prevent leaf yellowing on Oriental and Asiatic lilies.
· Testing postharvest treatments to prevent leaf yellowing on Alstroemeria.
Water Uptake and Water Stress
· Effect of hydration temperature on water uptake and vase life of roses.
· Testing stem submersion on leaf water content and postharvest quality of roses.
· Testing water surfactants (PSI Matrix and Capsil) on water uptake of roses.
· Evaluating relationships between stem water potential and vase life of cut rose flowers.
Sanitation Techniques
· Testing ozonated water dips on bacteria load on cut roses and gypsophila.
· The use of bactericides (chlorine dioxide, Phyton 27, ZeroTol) on postharvest performance of stock.
· Potential of chlorine dioxide biocide to extend longevity of cut carnation flowers.
· Potential of chlorine dioxide to extend longevity of Delphinium and snapdragon flowers.
· Evaluation of chlorine dioxide as a farm hydration treatment for cut flower bouquets.
· Evaluation of chlorine dioxide as a farm hydration treatment for cut rose flowers.
· Efficacy of chlorine-based biocides to extend longevity of cut Gerbera flowers.
· Relative efficacy of various biocides to extend longevity of cut Gerbera flowers.
· Relative efficacy of various biocides to extend longevity of cut flower bouquets.
· Capacity of a new purification unit to sanitize air in a cut flower cooler.
· Efficacy of farm hydration treatments to extend longevity of cut rose flowers.
· Evaluation of different wholesale hydration and anti-bacterial solutions for flower bouquets.
Best Care and Best Practices
· The use of STS and high sugar solutions at harvest on rose quality and longevity.
· Evaluation of STS on vase life and quality of rose varieties.
· Use of cold and warm hydration water to extend longevity of cut rose flowers.
· Influence of retail hydration treatment time on longevity of cut rose flowers.
· Influence of cut stem angle and solution depth on longevity of rose flowers.
· Effects of re-cutting stems during vase life on longevity of rose flowers.
· Use of sucrose-based treatments to improve opening of rose flowers.
· Potential of vacuum cooling to improve cut rose flower quality and longevity.
· Evaluation of different methods for shipping cut flowers from wholesales to retailers.
· Impact of ‘breaks’ in the cool-chain on quality and longevity of cut rose flowers.
Summary of Key Experiments Completed
I. Evaluating Grower, Wholesale and Retail Procedures to Prevent Leaf Yellowing and Extend Longevity of Cut Flowers.
We have tested several commercial products on several cultivars of Oriental lilies (‘Acapulco’, ‘Broadway’, ‘Kissproof’, ‘Noblesse’, ‘Star Gazer’ and ‘White Star Gazer’), Asiatic lilies (‘Chianti’, ‘Hilde’ and ‘Prato’) and Alstroemeria (‘Atlanta’, ‘Helios’, ‘Jupiter’, and ‘Red Kardinal’). Results showed that a 1 hour pulse in Chrysal BVB (0.1%) (Pokon&Chrysal) was the most effective product tested that prevented or significantly reduced leaf yellowing compared to Fascination (Valent BioSciences), PAL (Floralife, Inc) and thidiazuron (10 ppm). The other compounds also reduced leaf yellowing but were not as effective Chrysal BVB.
Vase life also increased significantly when Chrysal AVB (silver nitrate) was combined with Chrysal BVB. Treatments should be done at harvest or during wholesale to be the most effective. Specialized bulb food can also overcome leaf yellowing when no pre-treatment was applied. The more sensitive a variety was to leaf yellowing, the less reactive it was to the pulsing solution.
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Fig. 1. Control pulsed in water (left) verses pulsed in BVB+AVB (right) after 15 days in postharvest. |
Fig. 2. The effect of pulsing solutions on leaf yellowing of ‘Jupiter’ alstroemeria. |
II. Evaluating Procedures to Increase Water Uptake and Reduce Water Stress.
Part A. Hydration Solution Temperature
Alleviation of water stress through maintenance of high rates of water uptake during hydration can increase longevity of freshly harvested flowers. Likewise, we are evaluating and developing similar hydration protocols that will increase water uptake and longevity of dry-shipped flowers.
In a preliminary experiment, we evaluated the potential of pulse treatments maintained constantly at 35, 70 or 110 °F hydration solutions (as opposed to placing flowers in the specified temperatures and letting the water temperature adjust during pulse time) to improve quality and longevity of ‘Freedom’ rose flowers. Hydration was conducted at an air temperature of 70°F. Pulsing stems with either 70°F or 110°F commercial vase solution for 1 hour before a regular retail hydration (48 hours, 35°F) extended vase life of flowers by 2 days compared to flowers pulsed with a 35°F solution (Fig. 3). Flower opening was also more rapid for stems pulsed at 110 °F (Fig. 4).
Alleviation of water stress through maintenance of high rates of water uptake during hydration can increase longevity of freshly harvested flowers. Likewise, we are evaluating and developing similar hydration protocols that will increase water uptake and longevity of dry-shipped flowers.In a preliminary experiment, we evaluated the potential of pulse treatments maintained constantly at 35, 70 or 110 °F hydration solutions (as opposed to placing flowers in the specified temperatures and letting the water temperature adjust during pulse time) to improve quality and longevity of ‘Freedom’ rose flowers. Hydration was conducted at an air temperature of 70°F. Pulsing stems with either 70°F or 110°F commercial vase solution for 1 hour before a regular retail hydration (48 hours, 35°F) extended vase life of flowers by 2 days compared to flowers pulsed with a 35°F solution (Fig. 3). Flower opening was also more rapid for stems pulsed at 110 °F (Fig. 4).Alleviation of water stress through maintenance of high rates of water uptake during hydration can increase longevity of freshly harvested flowers. Likewise, we are evaluating and developing similar hydration protocols that will increase water uptake and longevity of dry-shipped flowers.In a preliminary experiment, we evaluated the potential of pulse treatments maintained constantly at 35, 70 or 110 °F hydration solutions (as opposed to placing flowers in the specified temperatures and letting the water temperature adjust during pulse time) to improve quality and longevity of ‘Freedom’ rose flowers. Hydration was conducted at an air temperature of 70°F. Pulsing stems with either 70°F or 110°F commercial vase solution for 1 hour before a regular retail hydration (48 hours, 35°F) extended vase life of flowers by 2 days compared to flowers pulsed with a 35°F solution (Fig. 3). Flower opening was also more rapid for stems pulsed at 110 °F (Fig. 4).
Alleviation of water stress through maintenance of high rates of water uptake during hydration can increase longevity of freshly harvested flowers. Likewise, we are evaluating and developing similar hydration protocols that will increase water uptake and longevity of dry-shipped flowers.In a preliminary experiment, we evaluated the potential of pulse treatments maintained constantly at 35, 70 or 110 °F hydration solutions (as opposed to placing flowers in the specified temperatures and letting the water temperature adjust during pulse time) to improve quality and longevity of ‘Freedom’ rose flowers. Hydration was conducted at an air temperature of 70°F. Pulsing stems with either 70°F or 110°F commercial vase solution for 1 hour before a regular retail hydration (48 hours, 35°F) extended vase life of flowers by 2 days compared to flowers pulsed with a 35°F solution (Fig. 3). Flower opening was also more rapid for stems pulsed at 110 °F (Fig. 4).
| Fig. 3. Vase life of ‘Freedom’ rose flowers pulsed with 35, 70 and 110 °F solution. | Fig. 4. Opening of ‘Freedom’ rose flowers was rapid for stems pulse-treated at 110 °F. |
We will continue to refine this treatment and also aim to:
1. Determine the impact of water stress on efficacy of conventional hydration treatments.
2. Improve on-farm hydration treatment protocols to minimize shipment water stress.
3. Improve retail hydration treatment protocols to increase water uptake and extend longevity.
Part B. Using Surfactants to Improve Water Status
The surfactants Psi Matric and Aquatrols Capsil were either sprayed on leaves and flowers, added to the vase solution, or stems were submerged for 4 hours to determine if these surfactants would help to overcome water stress and increase vase life. Our preliminary studies showed that there was no consistent benefit in using surfactants to increase vase life. The first study showed a 2-3 day increase in vase life and water uptake of ‘Charlotte’ only when sprayed or submerged in Psi Matric, but a repeat of the study did not show this trend. Submerging stems in Capsil actually decreased vase life and adding PSI Matric at 600 and 150 ppm to the vase solution severely damaged leaves but not flowers. None of the treatments had any detrimental affects on flower opening. Measurement of leaf water content showed that submerging flower stems helped to hydrate the leaves, as less water was taken up after submersion, but this relationship did not influence vase life.
III. Developing Effective Sanitation Techniques That Maximize Flower Longevity
Part A. Sanitation of flower solutions
Maintaining bacteria-free hydration solutions is vital for maximizing cut flower life. We evaluated the potential of chlorine dioxide (ClO2) (Selective Micro® Clean, Selective Micro Technologies) to reduce bacteria and extend flower longevity.
We have now screen-tested eleven popular cut flower species (Alstroemeria, carnation, chrysanthemum, Delphinium, Gerbera, Gypsophila, lily, rose, snapdragon, statice, stock) for benefits of ClO2. Flowers were obtained through valued links in California, Florida and Colombia. Addition of 10 parts per million (ppm) of ClO2 to vases extended the longevity of Gerbera ‘Monarch’, stock ‘Ruby Red’, and Gypsophila ‘Crystal’ flowers by 2-5 days (Fig. 5). ClO2 treatment greatly reduced the number of bacteria that grew in solutions (Fig. 6).
| Fig. 5. Gerbera ‘Monarch’ flowers exposed to 0 (left) or 10 (right) ppm ClO2. | Fig. 6. Accumulation of bacteria in vases containing 0 or 10 ppm ClO2. |
We also determined the efficacy of ClO2 relative to other biocides. Inclusion of 10 ppm of ClO2 in vase water extended longevity of Gerbera varieties ‘Lorca’, ‘Julia’ and ‘Vilassar’ by 1-4 days relative to control (i.e. water only) flowers. In two out of the three varieties, ClO2 treatment was either equal to or more effective than 8-hydroxyquinoline sulfate, stabilized pool chlorine, bleach and a commercial flower food (plus biocide) in extending flower longevity.
With a view to realizing the full potential of ClO2 for the cut flower industry, we still need to:
1. Determine optimal application protocols (e.g. exposure time) for ClO2 on a range of flowers.
2. Determine the compatibility of ClO2 treatments to work with common vase water additives.
3. Test the efficacy of ClO2 and commercial biocides to sanitize solutions and buckets.
4. Test the efficacy of ClO2 to sanitize cut flowers before shipment to prevent mold.
Part B. Sanitation of cooler air
Development of disease during postharvest storage often limits the marketability of cut flowers. We evaluated the ability of a new air purification unit to decrease levels of airborne microbes in a commercial wholesale floral cooler and reduce disease and quality loss in stored rose flowers.
In our evaluation, the air purification unit did not consistently reduce levels of bacteria, fungi and yeast in the floral cooler. The unit did, however, reduce the number of selected fungi (viz. Cladosporium cladosporioides, Cladosporium minourae and Penicillium rugulosum) in cooler air over a 5-day period. The unit did not extend the vase life of stored ‘Charlotte’ rose flowers. Movement of people in and out of the cooler may have diminished the effectiveness of the system. Further testing of this technology will be necessary for commercial adoption.
Part C. Sanitation of flower stems
Ozonated water, which is used in the fruit/vegetable and fish industry as a safe and relatively inexpensive microbial decontaminate, was tested on roses, gypsophila and sunflowers. Flower stems treated with ozonated water for 15 seconds or 15 minutes showed no detrimental effects on vase life or quality. In these studies, our non-treated control plants did not have visible microbial growth in the vases. This may have been attributed to treatments following harvest prior to receiving the product in our lab. This procedure does show promise, but it would not have the long-term residual effect that chlorine dioxide has. Further research needs to be conducted to determine if this method has value to our industry by controlling bacterial growth and improving vase life.
IV. Identify Best Care and Best Practices That Maximize Cut Flower Longevity and Quality
We are evaluating and identifying “Best Practices” at grower, wholesaler, retailer and consumer levels that consistently produce high-quality and long-lasting flowers for consumers. Our research is focusing on improving hydration, sanitation and cooling practices. We are working with the most popular varieties of Alstroemeria, carnation, chrysanthemum, lily and rose flowers.
Recently, we conducted preliminary experiments to examine the potential benefits of vacuum cooling flowers before and after airplane shipment. Vacuum cooling Colombian ‘Charlotte’ rose flowers prior to departure from Bogotá and again on arrival in Miami extended subsequent vase life by 4-5 days over flowers that were just kept in regular coolers (Fig. 7 and 8). In contrast to ‘Charlotte’, vacuum cooling did not improve the longevity of ‘Freedom’ rose flowers. The different response of rose varieties to vacuum cooling highlights the need for continued research into this technology. A second experiment is currently underway. These results should be considered as preliminary and no final conclusions should be drawn from these results at this time.
We are evaluating and identifying “Best Practices” at grower, wholesaler, retailer and consumer levels that consistently produce high-quality and long-lasting flowers for consumers. Our research is focusing on improving hydration, sanitation and cooling practices. We are working with the most popular varieties of , carnation, chrysanthemum, lily and rose flowers.Recently, we conducted preliminary experiments to examine the potential benefits of vacuum cooling flowers before and after airplane shipment. Vacuum cooling Colombian ‘Charlotte’ rose flowers prior to departure from Bogotá and again on arrival in Miami extended subsequent vase life by 4-5 days over flowers that were just kept in regular coolers (Fig. 7 and 8). In contrast to ‘Charlotte’, vacuum cooling did not improve the longevity of ‘Freedom’ rose flowers. The different response of rose varieties to vacuum cooling highlights the need for continued research into this technology. A second experiment is currently underway. These results should be considered as preliminary and no final conclusions should be drawn from these results at this time.We are evaluating and identifying “Best Practices” at grower, wholesaler, retailer and consumer levels that consistently produce high-quality and long-lasting flowers for consumers. Our research is focusing on improving hydration, sanitation and cooling practices. We are working with the most popular varieties of , carnation, chrysanthemum, lily and rose flowers.Recently, we conducted preliminary experiments to examine the potential benefits of vacuum cooling flowers before and after airplane shipment. Vacuum cooling Colombian ‘Charlotte’ rose flowers prior to departure from Bogotá and again on arrival in Miami extended subsequent vase life by 4-5 days over flowers that were just kept in regular coolers (Fig. 7 and 8). In contrast to ‘Charlotte’, vacuum cooling did not improve the longevity of ‘Freedom’ rose flowers. The different response of rose varieties to vacuum cooling highlights the need for continued research into this technology. A second experiment is currently underway. These results should be considered as preliminary and no final conclusions should be drawn from these results at this time.
We are evaluating and identifying “Best Practices” at grower, wholesaler, retailer and consumer levels that consistently produce high-quality and long-lasting flowers for consumers. Our research is focusing on improving hydration, sanitation and cooling practices. We are working with the most popular varieties of , carnation, chrysanthemum, lily and rose flowers.Recently, we conducted preliminary experiments to examine the potential benefits of vacuum cooling flowers before and after airplane shipment. Vacuum cooling Colombian ‘Charlotte’ rose flowers prior to departure from Bogotá and again on arrival in Miami extended subsequent vase life by 4-5 days over flowers that were just kept in regular coolers (Fig. 7 and 8). In contrast to ‘Charlotte’, vacuum cooling did not improve the longevity of ‘Freedom’ rose flowers. The different response of rose varieties to vacuum cooling highlights the need for continued research into this technology. A second experiment is currently underway. These results should be considered as preliminary and no final conclusions should be drawn from these results at this time.
| Fig. 7. Vacuum cooling ‘Charlotte’ roses in Bogotá and Miami (left) improved flower longevity relative to room cooling (right). | Fig. 8. Vase life of ‘Charlotte’ rose flowers following exposure to vacuum cooling in Bogota and/or Miami. |
For further information contact Dr. Terril Nell at tnell@ifas.ufl.edu
