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Green-seeds.com:
flowers & ornamentals: articles
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Postharvest Handling of Orchids
The postharvest handling of orchids requires care and attention to detail.
This bulletin deals specifically with Dendrobium orchids (Dendrobium phalaenopsis),
whose many hybrids produce purple, white, yellow, lavender, and bicolor
flowers. Healthy, strong Dendrobium orchids can have a 2- to 3-week vase
life if handled appropriately and transported to markets within 2 days of
harvesting. Orchids are susceptible to stress factors such as temperature
fluctuation, low humidity and temperature, contact with ethylene, and mechanical
damage, which can reduce orchids¹ marketability because of poor appearance
and shortened vase life. The shorter the time from harvesting to packing
and shipment, the longer vase life will be.
Export Criteria
Dendrobium orchids produced and packed for export are carefully graded,
by hybrid and by spray length and quality. Most importers require that at
least half of the flowers be open, with good sprays having 10 or more flowers.
Market needs and importer requirements vary considerably among and within
importing countries. Spray size, maturity, number per carton box, and carton
type are factors producers should take into account when initiating export
contracts.
Hybrids
 New hybrids are introduced
continually, but certain criteria are used to evaluate all varieties. Good
Dendrobium hybrids should produce 10 or more flowers per spray with at least
5 sprays per plant per year. Flowers should have a diameter of at least
6 centimeters (2.5 inches). Vase life should also be a consideration with
hybrid selection. Characteristics of available varieties are:
Thai Varieties: Individual
flowers are large and showy. Spray lengths are medium to long. Plants typically
yield 6 to 9 sprays per year. Vase life is 10 to 14 days.
Hawaiian Varieties:
The University of Hawaii¹s varieties are medium-sized and not showy.
Spray lengths are long to extra long. Plants yield 16 to 24 or more sprays
per year. Vase life is 14 to 21 days.
Some hybrids popular
in Thailand and Hawaii are listed below:
Thailand: Sonia 16,17,
28; Venus; BM White; Bom 16; Bom 28; Ecopel; Barbara; Sakura; Savin # 5;
White Caesar; Lucian Pink; Christine; Anna; Fantacia; Chanel; New Pink;
Selangor; Beauty; Candy Stripe; Kasem Boonchoo; Chao Praya; Udom; and Kultana.
Hawaii: UH 232, UH 919,
UH 503 Uniwai Prince, UH 509 Prince, UH 507 Uniwai Princess, UH 44 Jaque-line
Thomas, UH 306 Jaqueline Hawaii, UH 800 Iniwai Mist.
Harvest Maturity
Dendrobium sprays should
be harvested at least twice a week during peak production periods, and once
a week during low periods. The harvesting frequency depends on production
conditions, seasonality, and the hybrid. The length of time before the flowers
are fully watered on arrival also should be considered. Dendrobiums are
harvested when 30 to 40 percent of the flowers are open and the top flowers
are in bud, although this practice varies depending on spray length and
total number of flowers. Guidelines are given in Table 1.
Table 1: Spray-Length and Flower-Condition Guidelines
for Dendrobium Orchids Exported
by Thailand and Hawaii
|
Species/Grade
|
Spray
Length
|
Number
of
Flowers and Buds
|
Open
Flowers
|
|
Thailand
|
|
Purple - Super Long
|
56 - 61
cm
|
14
|
6
|
|
- Extra Long
|
51 - 56
cm
|
-
|
-
|
|
- Long
|
46 - 51
cm
|
11 - 13
|
5
|
|
- Medium
|
41 - 46
cm
|
8 - 10
|
4
|
|
- Small
|
36 - 41
cm
|
-
|
-
|
|
White
- Long
|
> 45
cm
|
13
|
6
|
|
- Medium
|
35 - 45
cm
|
9
|
5
|
|
Hawaii
|
|
- Grande
|
> 60
cm
|
-
|
-
|
|
- Deluxe
|
55 - 60
cm
|
-
|
-
|
|
- Long
|
50 - 55
cm
|
-
|
-
|
|
- Standard
|
45 - 50
cm
|
-
|
-
|
|
- Short
|
32 - 45
cm
|
-
|
-
|
|
- Mini
|
< 32
cm
|
-
|
-
|
Harvesting Techniques
To remove Dendrobium
sprays from the plant, harvesters either break them off with a rapid downward
movement or cut them off at the base with a sharp blade. The use of harvesting
blades can facilitate the transmission of viruses between plants, however,
and is normally slower. With the former method, the worker snaps with one
hand and holds between 10 and 20 harvested sprays in the other, depending
on the diameter of the spray stem and the size of the hand. The worker should
not carry too many sprays to prevent damage to the stems and flowers. The
operations of the harvester must be considered in developing flowerbed design
and layout. The height of the flower at harvest, the depth of the beds,
and the distance to the end of the beds must facilitate harvesting and minimize
the risk of mechanical damage.
After they are picked,
sprays are transferred to buckets containing clean water that is 10 centimeters
deep. Cleanliness of the buckets and the water is important to prevent disease
contamination of cut stems. Buckets should be placed at a central point
for transport to the packing area.
In some cases, operations
can be made more efficient by carrying out preselection activities in the
field. Harvesters place several water buckets at the end of the beds, and
use the buckets to sort stems by grade. This process assists the graders
in the packhouse.
Buckets with flowers
should be transported to the packing facility as soon as possible after
harvest. The distance to the packhouse should be minimized. If trolleys
or trailers are used for transport, they should have fitted inserts for
buckets. The longer the delay between harvesting and packing, the shorter
vase life will be. Flowers should not be exposed to direct sunlight, rain,
or winds. Such exposure increases water loss, and the amount of water a
flower loses in the initial stages of postharvest can greatly affect vase
life.
Grading and Packing
Efficient and timely
grading and packing help maintain quality and extend vase life. The packhouse
should be covered and free from strong drafts to prevent moisture loss.
Floors, cold rooms, tables, buckets, knives, and other equipment should
be cleaned regularly with chlorine or other biocides. Good lighting in the
packhouse is important to enable graders and packers to see coloration and
identify problems.
The packhouse should
be designed to permit a continuous flow of flowers and structured so that
there is no mixing of graded sprays with non-graded. Similarly, the final
packed product should be physically separate from incoming buckets from
the field.
Individual sprays should
be checked by the grader and, after classification, placed on the appropriate
area of the grading tray or table. Sprays should not be stacked more than
15 to 20 centimeters deep because piling them higher than that can result
in mechanical damage. Tables should be covered with thin foam to help avoid
mechanical damage to the flowers. Flowers that do not meet the required
minimum grade are rejected, and the remaining flowers are separated into
length and quality categories. Graders need to check for the following:
* Number of flowers/buds;
* Uniformity of flower color (discoloration may be the result of thrips);
* Maturity‹the number of open flowers compared with the number of
buds;
* Flower blemishes;
* Missing floral parts and missing flowers;
* Presence of twisted or deformed flowers;
* Stem length;
* Stem curvature (distorted flower spikes may be the result of thrips);
* Evidence of insect damage‹brarticularly fine silver sbrecks caused
by thrips and flowers eaten by beetles;
* Presence of flower blight or other fungi (Botrytis, Colletotrichum),
indicated by speckling or spots on the flowers;
* Presence of virus, indicated by streaking of the colors or color break;
and
* Presence of insects (mealy bug, scale insects, and aphids).
Uniformity of the product
is an essential factor, and if qualities are mixed, the price may be determined
based on the worst-quality spray in the box. Grades depend on the final
export market and on local market sales; some markets may require a specific
number of flowers and buds, certain flower sizes, and particular stem lengths.
The specifications vary based on the season‹that is, whether the flowers
are abundant or in short supply. Examples of some length grades for Hawaii
and Thailand are given in Table 1.
After the sprays have
been graded, they can be packed. Grading and packing are best done as a
single operation by one person, rather than as a two-step operation in which
one person classifies and one packs. Combining the two steps speeds up the
operation and prevents flowers from mounting up on grading tables.
Hydrating, grouping,
and sleeving take place next. To keep flowers from dehydrating, packers
place a small wad of moist cotton on the base of each spray, covered with
a small piece of plastic film (6 x 6 centimeters) held in place with an
elastic band. Alternatively, packers may use plastic vials or water-pics,
which are filled with water and, in some cases, a preservative solution.
Packing can be carried out in single sprays or in bunches with the stem
bases aligned. The number of sprays in a bunch depends on market or buyer
requirements, but 5 or 10 are standard. Bunches are normally placed in clear
plastic sleeves. The design of the sleeve depends on market requirements
and may be perforated.
After sleeving, the
flowers are packed in fiberboard trays that are then packed in master cartons.
The system of packing should afford maximum protection against mechanical
damage. This involves placing the bunches in the first layer with stems
against both end walls, and placing a second layer so that flowers overlay
stems and stems overlay flowers. This method helps reduce mechanical damage
to the flowers. There is no standard number of flowers per tray, but trays
contain up to 100 medium-sized sprays and 70 extra-long sprays.
Packaging
There is no standard
packaging recommended. Specific market or buyer requirements should be determined
in each case. U.S. and European packs are normally denser than those for
Japan. Different sizes of boxes may be used for different spray length.
Cartons normally do not have ventilation holes. Examples of packaging dimensions
are given in Table 2.
Table 2: Packaging for Dendrobium Orchids
|
Country
of Origin/
Destination
|
Tray
Dimensions:
L x H x W
(cm)
|
Trays
per Master
|
Spray
Length
and Number
|
|
Hawaii
|
102.5 x
40 x 7.5
|
4 - 6
|
-
|
|
82.5 x 37.5
x 7.5
|
4 - 6
|
-
|
|
Thailand/Europe
|
75 x 39
x 38
|
5
|
Single Long, 60/tray, 300/carton;
Single Short, 80/tray,
400/carton
|
|
Singapore/Japan
|
77 x 22
x 8
|
0
|
Long, 20 sprays
|
|
Singapore/Japan
|
77 x 22
x 7
|
0
|
Medium, 20 sprays
|
|
Singapore/Japan
|
77 x 22
x 6
|
0
|
Short, 20 sprays
|
|
Singapore/Japan
|
100 x 30
x 40
|
5
|
40/tray, 200/carton
|
Storage and Transportation
Shipping as soon as
possible after harvest and avoiding storage will result in the longest vase
life. The longer the product is in storage before shipment, the shorter
the vase life. If storage is necessary, Dendrobium orchids should be held
at 10°C to 12°C; temperatures below 8°C cause chilling injury
and subsequent damage. The extent of low-temperature damage depends on the
actual temperature and the time in storage.
Storage in cold rooms
or areas that contain ethylene-producing fruit should be avoided. Cleanliness
is important; rotting material in the packhouse or store rooms creates high
levels of ethylene. The presence of ethylene drastically affects the flower
quality, aborting buds, advancing senescence, and reducing vase life. Affected
flowers will turn brown.
For air shipment, aircraft
pallets are preferred to containers. When aircraft containers are used,
orchids should not be mixed with ethylene-producing products. In all cases,
direct exposure to ambient conditions, particularly sunlight and rain, should
be avoided.
Potential Postharvest Losses
Dehydration:
Water loss can occur if flowers are not shipped immediately after harvest
and if they are stored under ambient conditions. Importers can correct
this damage by submerging the sprays in water for 10 to 15 minutes, time
enough to rehydrate them.
Mechanical Damage:
Mechanical damage occurs when flowers are handled poorly or overpacked.
Most of this damage is not visible when the sprays are packed, but develops
during transport and storage. Most of the damage is to the flowers, including
creasing and flower removal. In severe cases, the stem may be damaged
or crushed.
Export Specifications
There is considerable variation in market requirements for Dendrobium
orchids. Spray lengths, flower number and condition, flowers per tray,
trays per box and the overall packaging vary by importing country and
by importer.
Characteristics:
Flower color should be uniform according to the hybrid characteristics.
All flowers should be clean and fresh with no dehydration or discoloration.
Approximately 40 to 50 percent of the flowers should be open with the
remainder in the bud stage.
Spray Lengths:
Sprays of different lengths are separated and packed accordingly, resulting
in a range of up to six sizes from approximately 32 to 60 centimeters.
Exporters should consult Table 3 for guidelines, but confirm terminology
and lengths with buyers before packing.
Table 3: Spray-Length Categories
Table 3: Spray-Length Categories
| Size |
Length (cm) |
| Super Long |
55-60 |
| Extra Long |
50-55 |
| Long |
45-50 |
| Standard |
40-45 |
| Short |
35-40 |
| Mini |
30-35 |
Spray Lengths: Sprays should not be above the required maturity stage,
indicated by the openness of 40 to 50 percent of the flowers. Flowers and
stems should not be twisted or deformed. Specifically, they should be free
from the following:
* Wounds from harvesting or handling, including punctures, scratches or
bruises;
* Flower blight or other fungi; and
* Insects and insect damage.
Retail Handling and Consumer Care: For maximum vase life, importers and
retailers should keep flowers at 10°C to 12°C and recut and rehydrate
sprays by refilling the plastic vials with preservative solution. Consumers
should also recut stems and avoid placing the flowers in areas of extreme
temperature fluctuation and rapid air movement. The flowers should also
be kept away from ripening fruit.
Sources of Technical Information
Goh, C.J., A.H. Halevy,
R. Engel, and A.M. Kofranek. 1985. ³Ethylene evolution and sensitivity
in cut orchid flowers.² Scientia Horticulturae 26 (1): 57-67.
Kunisaki, J.T. 1976.
³Dendrobium spikes with floral preservatives.² University of Hawaii
Cooperative Extension Service Miscellaneous Publication No. 134.
Orchid Society of South
East Asia. 1993. Orchid Growing in the Tropics. Times Editions Pte Ltd,
Singapore.
Uchida, J.Y. and M,
Aragaki. 1991. ³Fungal diseases of Dendrobium flowers.² Research
Extension Series 133. College of Tropical Agriculture and Human Resources,
University of Hawaii.
Wanitprapha, K., K.M.
Yokoyama, S.T. Nakamoto, K.W. Leonhardt, and J.M. Halloran. 1991. ³DendrobiumEconomic
fact sheet # 13.² Department of Agricultural and Resource Economics,
University of Hawaii.
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Green - Seeds Co., Ltd.
81/10B Ho Van Hue Street, Phu Nhuan District, Ward 9, Ho Chi Minh City, Vietnam
Tel: +84 (8) 847 6901 - Fax: +84 (8) 844 1392 - Email: info@green-seeds.com
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