Hydrating and Holding Solutions

NORTH CAROLINA STATE UNIVERSITY’S REPORT FOR 2017 ON THE POSTHARVEST TREATMENT OF SPECIALTY CUT FLOWERS HIGHLIGHTS THE EFFECTIVENESS OF TWO TREATMENT SOLUTIONS.

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Hydrating and Holding Solutions

Every year at North Carolina State University, the Horticultural Science department of the College of Agriculture and Life Sciences conducts vase-life studies on promising species and cultivars from the ASCFG Seed and Perennial Trials. Most recently, we tested the vase life of 25 such cut flowers.

During our studies, we found that vase life was longest for most of the cut flowers when they were placed into a holding solution (low-dose/low-sugar nutrient solution), and for some, the best results were obtained when we placed the flowers into a hydrator (hydrating solution) before the holding solution.

Our testing over the years has shown that the vase life of Lisianthus/Eustoma is significantly increased when these flowers are placed into holding solutions or receive both hydrator and holding treatments. Similarly, Hibiscus ‘Mahogany Splendor’, which has become a popular cut foliage despite issues with postharvest handling, responded very well to a hydration solution treatment after harvest, increasing its vase life by three to five days and reducing the chances the stems would wilt within the first couple days.

WHAT ARE HYDRATING AND HOLDING SOLUTIONS?
Some of you may be asking, “What are hydrating solutions and holding solutions?” Cut flower treatments can be categorized as hydrating, holding or vase solutions.

Hydrating solutions are meant to be administered to cut flowers right after harvest and/or following a period of dry transport, prior to a holding solution, to facilitate water uptake. These solutions improve the flow of liquids through the flower stems by clearing air and natural compounds blocking stem cell passageways. They do not contain a carbohydrate (nutrient) source. Hydrating solutions are usually used for a short amount of time, such as four hours.

Holding solutions contain a carbohydrate source (sugar) to encourage bud opening and/or flower longevity and are administered to cut flowers for several hours up to approximately two days either by growers or wholesalers before the flowers get to the end consumers.

Vase solutions (full-dose nutrient solutions) are generally used by florists in arrangement containers and by consumers when they place their flower purchases in water. Vase solutions contain a higher concentration of carbohydrates than holding solutions. While we do not test the use of vase solutions in these studies, it would be safe to assume that those flowers that perform better with a holding solution would likely last longer for your customers with a vase solution.

ONE MORE THING
Our testing methods tend to produce the maximum vase life, which tells you the potential vase life of each species. We cut and process the stems rapidly, put one stem per jar, and use a postharvest evaluation temperature that is a bit cooler than a typical home in a Southern summer. These procedures are set up to provide a consistent environment so that anyone else should be able to repeat our work and get the same results. These factors, combined, typically add about one to three days to the vase life of some species and cultivars compared to what a grower would usually get. It is also important to note that these results do not replace in-house testing, as there are many on-farm factors that affect vase life.

Hydrating and Holding Solutions

Hydrating and Holding Solutions

Hydrating and Holding Solutions

Hydrating and Holding Solutions

Hydrating and Holding Solutions

This project was supported by the Association of Specialty Cut Flower Growers Research (ASCFG) Foundation and numerous suppliers. This article first appeared in the Winter 2018 edition of ASCFG’s The Cut Flower Quarterly magazine. See that issue for complete results.

OUR METHODOLOGY
Field-grown flowers were harvested at the optimum stage of flower development and placed into tap water (0.21 EC, 6.1 pH). Stems were sorted into four equal groups and placed in the treatments below for the specified time, then placed into vases of deionized water.

• Hydrator only (4 hours)
• Holding solution only (2 days)
• Hydrator for 4 hours followed by holding solution for 2 days
• Tap water only (as a control)

We used Floralife Hydraflor 100 as the hydration solution and Floralife Professional as the nutrient solution, both at the rates listed on the packaging. After treatment, stems were placed in tap water and held at 68 ± 2 oF under approximately 200 foot-candles of light for 12 hours per day. The vase life for each stem was recorded. Termination point was typically when 50 percent of the flower(s)/florets on the stem were brown, wilted, drooped over, etc.

SELECTED RESULTS

Antirrhinum (Snapdragon) Maryland Dark Orange’
Flowers treated with a holding solution displayed a slightly increased vase life to 10 days. Untreated flowers had a vase life of 9 days.

Dianthus barbatus ‘Magenta Bicolor’
Flowers treated with both hydrator and holding solutions had the longest vase life of 15 days, followed by the untreated flowers at 14 days, and flowers treated with only a hydrator at 12 days.

Helianthus annuus ‘EH16-10’
Flowers treated with only a holding solution had a slightly longer vase life (14 days) than flowers that received both treatments (13 days). Untreated flowers lasted 12 days.

Hibiscus ‘Mahogany Splendor’
This cut foliage responded very well to treatment with a hydrator, which increased vase life to 18 days from only 13 to 15 days without a hydrator. Treating the stems with hydrator decreased the likelihood they would wilt within the first couple of days. Interestingly, the stems started to root after about two weeks in the vase, which was too late, of course, to prevent the wilting that occurred after harvest.

Lisianthus/Eustoma ‘Rosanne 1 Black Pearl’
Flowers treated with both hydrator and holding solution had the longest average vase life (14 days) followed by flowers treated only with a holding solution (13 days) or only with hydrator (12 days). Untreated flowers had the shortest vase life (9 days).

Lisianthus/Eustoma ‘Rosanne 1 Green’
Flowers treated with both hydrator and holding solution had the longest average vase life of 16 days as compared to 12 days of flowers without any treatments or just a hydrator.

By Cristian Loyolla; John Dole, Ph.D.; Ingram McCall; and Ben Bergmann, Ph.D.
Department of Horticultural Science, North Carolina State University