Cut Flower - Precooling , pulsing and holding techniques

Post harvest handling techniques of cut and loose flowers – Precooling , pulsing and holding techniques

1. Post harvest handling techniques of cut and loose flowers –
Precooling , pulsing and holding techniques
Lecture No.: 28

2. Pre cooling
•Pre cooling is an important operation in post-harvest handling
and transport of flowers
•Function : fast removal of field heat
•Should be done immediately after harvest
•Its reduce the tissue temperature - lower down all the catabolic
activities like respiration, transpiration, ethylene biosynthesis, etc.
and ultimately improve the vase life.

3. PURPOSE OF PRE COOLING
•Lowers respiration rate and decrease the breakdown of
nutritional and other stored materials in the stems, leaves and
petals
•Delays bud opening and flower senescence
•Prevents rapid water loss and decreased flower sensitivity to
ethylene
•Pre-cooling techniques - room cooling, forced air cooling,
hydro-cooling, vacuum cooling and ice bar cooling etc.

4. Pre cooling temperature required by different flower
crops
Crop Pre cooling temperature
Alstroemeria 4
o
C
Anthurium 13
o
C
Cattleya 7-10
o
C
Dendrobium 5-7
o
C
Rose 1-3
o
C
Gladiolus 4
o
C
Chrysanthemum 0.5-4
o
C

5. Author Report
Jitendra Kumar et
al., 2017
Pre cooling at 4°C for 24 h with CFB packaging for 16 h
records the maximum increase in quality and vase life of cut
rose cv . First Red
Mwangi et al.,
(2003)
Pre cooling in cut rose cv. Golden Gate with cool storage at
4°C for 24 h and pulsing with 2% dimethyl sulphoxide
(DMSO) for 15 min - gave maximum vase life
Pre cooling

6. Conditioning
•Simple process - flowers are kept standing loosely in a big container so
that air can circulate around the stems.
•Purpose - to restore the turgidity of cut flowers
•Achieved by treating the flowers with demineralized water supplemented
with germicides and acidified with citric acid to pH 4.5 to 5.0
•Hydration was improved when water was de-aerated or acidified wetting
agent like Tween 20 at the rate of 0.01 to 0.1 % was added.
• Flower stems were placed in preservative solution in plastic jars at a
depth of 2-4 cm and held at room temperature or in cold storage for
several hours.

7. Chemicals for conditioning cut flowers
Cut flower Chemical
Carnation STS (0.5 Mm) + 75 – 100 g/l sucrose (20 – 24 hr)
Gladiolus Sucrose (100 g/l ) + STS (4 Mm) 24hr
Rose 500 ppm citric acid @ 0-1
0
C 12 hr

8. Impregnation
•Flower stems impregnated for a short time with chemicals
•Use - Protects the blockage of the xylem vessel due to microbial
attack
•Chemical used - silver nitrate, nickel chloride or cobalt chloride
•Concentration (1000 ppm-1500 ppm) for 10-15 minutes
improved the longevity of several flowers such as aster, gerbera,
gladiolus, carnation, chrysanthemum, and snapdragon

9. Pulsing
•The absorption of chemical solutions containing sugars and
germicides through the lower cut bases of flower stems was
known as pulsing
•Sucrose – carbon source
•chemicals - STS, AgNo
3, HQ, MH, AOA, CaCl
2, CoCl
2, nickel
sulphate, aluminium sulphate and benzyl adenine
•Use - Prolongs life, promotes opening and improves the
colour and petal size through osmo-regulation

10. Bud opening solutions
•Flowers which are harvested at stage earlier than that of commercial stage,
require special treatments for opening of flower are treated with some specific
chemical solutions known as bud opening solutions.
•It increased longevity of cut flowers by reducing the sensitivity of flowers to
extreme temperatures, low humidity and ethylene
•Save space during shipment and extending the useful storage life
•Sugar concentration is lower than the concentration of pulsing
•Temperature is also kept lower
•High humidity is needed to prevent desiccation
•It should be done in controlled light, humidity,
temperature and air circulation

11. Standard Holding / vase solutions
•The vase solution should contain sugars, acidifying agent and a
biocide

•Acidifying agent - Citric acid

•Biocide - hydroxyl quinoline

•Metallic salts - silver nitrate, cobalt chloride, aluminium
sulphate, zinc sulphate, calcium nitrate and nickel chloride

•Growth regulators - BA, IAA, NAA, 2,4,5-T, GA
3, CCC