The Effect of Various Postharvest Treatments on the Water Balance and

Keeping Quality of Cut Anthuriums

Clement K. Sankat Saheeda Mujaffar

Agricultural Engineering Programme, Department of Mechanical Engineering,

The University of the West Indies,St. Augustine, Trinidad,

West Indies.

The Anthurium

Spadix (protrusion with hundreds of tiny

flowers)

Spathe(glossy petal-like

leaf)

Stem

“Trinidad Pink”

Symptoms of Anthurium Senescence

Spadix Necrosis (browning and drying)

Spathe Blueing & Browning

Loss of Spathe Gloss

The balance between water uptake and transpiration, called “water balance”, is a major factor affecting the longevity of cut flowers, as the most common reason for the termination of vase life is wilting and not natural senescence. Postharvest treatments for cut flowers (such as the addition of preservatives or biocides) are therefore aimed at improving this water balance.

The objective of this study was to investigate the effect of three simple postharvest treatments (floral preservative, silver nitrate pulsing and waxing) on modifying the water balance and keeping quality of cut “Trinidad Pink” anthuriums stored under ambient (28°C) and refrigerated (18°C, 13°C) conditions.

Introduction

Treatment 1: Silver Nitrate PulsingUndamaged flowers which were ¾ mature were allowed to stand in a dilute solution of silver nitrate (1 milliMolar) for 15 and 60 minutes prior to storage. The stems were then rinsed in a flowing stream of distilled water and flowers placed singly in plastic bottles containing distilled water.

Treatment 2: Floralife A commercial floral preservative, Floralife (Floralife Inc., South Carolina, U.S.A.) was used. Anthuriums were placed singly in plastic bottles containing the preservative solution at 1, 5, 10 and 20g/L.

Treatment 3: WaxingA small paintbrush was used to apply a thin coat of a liquid wax Fresh Mark 51V (Fresh Mark Corporation, Florida) directly to the spadix of the anthurium. Treated flowers were then placed singly in plastic bottles containing distilled water.

The mouth of each bottle was sealed with waterproof parafilm to ensure that water loss occurred only via the flower and the sealed bottles containing the flowers were placed in refrigerated storage chambers set at 13°C and 18°C (80-90% RH) and under ambient conditions (28°C, 60-80% RH) for a maximum of 30 days. Preservative solutions and water were changed every 5 days.

Materials & Methods

Mouth of bottle sealed with parafilm

Bottle containing

water or preservative

Measuring the Water Relations of Cut Anthuriums

The balance between transpiration and water uptake was described using a Transpiration:Uptake Ratio.

Transpiration rate was calculated as the difference between consecutive weighings of (a) and water uptake rate was calculated as the difference between consecutive weighings of (b) divided by the time interval. Changes in flower fresh weight (c) were expressed as a % change over the initial fresh weight. Flowers were considered marketable if they showed less than 5% spathe blueing, less than 10% spadixnecrosis, minimum loss of spathe gloss, weight loss of no less than 5%, and a transpiration: uptake ratio of less than 1.5 (Sankat & Mujaffar, 1994).

The following were measured at the start of the experiment and at 5-day intervals:

(a) Weight of bottle + water + flower(b) Weight of bottle + water(c) Weight of flower

Calculations

Silver nitrate pulsing (1mM, 15 min) significantly reduced shelf life of cutanthuriums stored at all temperatures (p≤0.001). Treated flowers showed lower water uptake rates but higher transpiration rates than those of control flowers. This resulted in the development of a water deficit and a rapid increase in transpiration:uptake ratio and a more rapid decline in fresh weight compared with control flowers. Pulsing of anthuriums for a longer period (60 minutes) did not improve shelf life. The effect of silver nitrate pulsing on shelf life has been previously shown to vary when anthurium blooms are stored in water.

Results Silver Nitrate Pulsing

Holding anthuriums in dilute Floralifesolutions (1g/L and 5g/L) resulted in a small increase in shelf life of flowers stored at 28°C and 18°C and these flowers maintained slightly higher fresh weights and lower ratios compared with untreated flowers, indicating that the more dilute solutions did have a small positive effect on the water balance on the anthuriums. Flowers held in Floralife(20g/L) and stored under ambient and refrigerated conditions deteriorated at a faster rate than control flowers (p≤0.001).

Floralife did not therefore demonstrate superiority over holding stems in distilled water. This may indicate that stem plugging due to microbial activity is not responsible for the termination of vase life.

Results – Floralife

Waxing of the spadix tissue alone was found to significantly (p≤0.001) extend the shelf life of anthuriums under ambient and refrigerated storage.

While control flowers stored under ambient conditions deteriorated rapidly after 5 days, waxing of the spadix tissue alone was found to decrease water loss due to transpiration and maintain a positive water balance for up to 14 days without adversely affecting the appearance of the bloom.

Waxed flowers stored at 18°C maintained higher fresh weights and lower transpiration rates than control flowers, and after 23 days of storage the transpiration:uptake ratio averaged 1.31. Control flowers at 18°C deteriorated after 19 days.

Results – Waxing

Holding cut anthuriums under refrigerated conditions (13°C, 18°C) positively affects storage behaviour and shelf life.

Silver nitrate pulsing (1mM, 15 min or 60 min) and concentrated Floralife solutions (10 and 20g/L) noticeably decrease anthurium shelf life while dilute Floralifesolutions (1 and 5g/L) show at best results which are marginally better to holding flowers in water.

Waxing of the spadix reduces water loss, maintains fresh weight and extends the shelf life of flowers stored under ambient and refrigerated conditions. Coatings such as Fresh Wax 51V are a simple, environmentally friendly, and relatively inexpensive technology that can be used to extend the shelf life of cut “Trinidad Pink”anthuriums.

Conclusions

0

5

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Shel

f Life

(Day

s)

28ºC 18°C 13°C

Temperature (°C)

Control

Silver Nitrate Pulsed

Effect of silver nitrate pulsing on the shelf life of cut anthuriums

Shelf life of anthuriums held in Floralife (5g/L)

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Effect of waxing on the shelf life of cut anthuriums.

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ControlWaxed

Effect of waxing on the water relations of cut anthuriums.

Control WaxedX% Change in FW Tran:Uptake Ratio

28°C

18°C

13°C

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Time (Days)

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