Postharvest Biology and Technology of Ornamentals

Putting science into practice

Michael Reid, University of California, DavisCai-Zhong Jiang, USDA-ARS, Davis

• Floriculture crops : Cut flowers, cut cultivated greens, foliage plants,

potted flowering plants, annual bedding/garden plants, propagative floriculture material

• Nursery crops : Evergreens_broadleaf, coniferous, Trees_shade,

flowering, Christmas, fruit and nut plants, transplants, shrubs and other ornamentals and propagation material

Ornamental Industry

The California nursery and floriculture industry

Value of California’s agriculture

2005 total $31.7 billion

Field crops, $3.09

Greenhouse, Nursery &

Floriculture, $3.44

Vegetables & melons, $6.25 Livestock &

poultry, $8.45

Fruits and nuts, $10.47

Data from the California Department of Food and Agriculture.

Contrast with cookies

5,000

5,500

6,000

6,500

7,000

7,500

8,000

8,500

9,000

9,500

10,000

1984 1989 1994 1999

Co

ok

ie &

cra

ck

er

sa

les

($

m)

What’s the problem?• Low per capita consumption of

cut flowers–Holidays–Weddings–Funerals

• Very low personal use

• Low per capita consumption of cut flowers–Holidays–Weddings–Funerals

• Very low personal use

Purchases of Cut flowers (retail) per capita in 2002 (in NTD)

• Switzerland 4000• Netherlands 2400• Belgium 1760• Germany 1600• U.K. 1600• Italy 1320• France 1320• Spain 760• Portugal 640• Poland 280• U.S. 200• Russia 120

Source, Flower Council of Holland

The postharvest problems

• Flowers are shipped long distances and stored for long times

• >25% product losses in marketing chain

• Flowers and potted plants don’t last long enough

• International market, strong competition

• Lower consumer satisfaction. Customers don’t return

• Species and cultivar• Temperature• Damage and disease• Water supply• Ethylene and other PGRs• Food supply• Growth

Factors affecting the postharvest life of ornamentals

Genetic difference in vase life among rose genotypes

0

5

10

15

20

2534

19

Ven

dela

4526

3335

4513

4040

4397

4372

3378

4410

3026

4029

Blu

shin

g A

kito

Brid

al A

kito

Dar

k E

ngag

emen

t

3358

Vas

e lif

e (d

ays)

Temperature - why is it important?

• Rate of deterioration a rate of respiration• Faster respiration, shorter life• Respiration increases exponentially with T

y = 22.622e0.0847x

R2 = 0.9936

0

50

100

150

200

250

300

350

0.0 5.0 10.0 15.0 20.0 25.0 30.0

temperature (C)

ml C

O2

/ kg

hr

Roses held 5 days at different temperaturesthen 8 days in vase life room at 20⁰C

2.52.5 55 7.57.500 1010 12.512.5

Temperature, respiration rate & vase life in stock flowers

y = 0.0012x4 - 0.0619x3 + 1.2003x2 - 3.6913x + 25.509

R2 = 0.9974

0

50

100

150

200

250

300

350

0.0 5.0 10.0 15.0 20.0 25.0 30.0

Temperature (C)

Resp

iratio

n (ml

CO2

/ kg h

r)

y = -0.0299x + 7.1564R2 = 0.9426

0

1

2

3

4

5

6

7

8

9

0 50 100 150 200 250

Total CO2 respired during storage (x100) ml CO2/kg

Vase

life a

fter s

torag

e (da

ys)

Postharvest Disease

Postharvest disease (primarily caused by gray mold (Botrytis cinerea) is a common cause of poor quality and shortened vase

life

Disease control strategies

Host

Environment

Pathogen

The disease life cycle

The disease triangle

Disease

Disease control – the pathogen

Reduce spore loado sanitation in field, greenhouse, shed

Prevent spore germinationo reduce condensation, injury, temperature

Prevent fungal entryo care in handling

Disease control - the host

Maintain in good condition, grow healthy plants, enhance physiological resistance.

Molecular biology-introduce resistance genes

Select resistant cultivars-variance is commonly observed

Treat with fungicides

Fungicides Rely on synthetic

chemical fungicides Effective Applied by dipping, in

fogs Development of

resistance Safety & environmental

concerns

Sodium hypochlorite (NaOCl)

• A strong oxidizing agent with broad spectrum antimicrobial activity

• Active ingredient in household bleach

• Commonly used for reducing bacterial and fungal contamination on fruit and vegetable surfaces and in flower vase solutions

Using NaOCl to control Botrytis infection in cut rose

Optimal concentration of sodium hypochlorite for controlling botrytis on rose ‘Akito’ and ‘Gold Strike’

flowers

No dip 0 100 200 400 800

Bo

trytis in

cid

en

ce

(%

)

0

20

40

60

80

100 'Akito' 'Gold Strike'

NaOCl concentration (µL L-1)

aa

a

a

b

bb

bb

b b b

Water supply

• Plants are mostly water (80-90%)

• Loss of water causes– loss of quality– wilting– accelerated aging– (ethylene production)

Failure in water relations

• Water uptake < transpiration• Xylem occlusion

– Emboli– Hard water– Bacteria– Physiological plugs

Air emboli• Recut under water• Acidify the water• Use warm (or cold) water• Pressurize (20 cm H2O)

• Use a brief detergent dip

Water depth

20 cm 10 cm 5 cm

• Roses dehydrated 10%

• Recut• Placed in different

water depths• Photograph taken

after 4 hours

Bacterial contamination

The Problem Desiccation of potted plants

Lack of proper wateringAt the retail level

ControlTraining retail staffTreatments to close stomata

Salt stress?ABA?

Chemical manipulation of ABA Level

Well-watered NaCl ABA No water

Ethylene-dependent senescence

Carnation model system Ethylene production prior to onset

of natural senescence Pollination accelerates ethylene

production and senescence

1-MCP - a new ethylene inhibitor

Ethylene

1-MCP

• Ed Sisler, NCSU• Mimics ethylene, blocks the

binding site• Marketed for flowers as EthylBloc• For fruits and vegetables as

‘SmartFresh’

Studies on environmental requirements

• Experiments to determine the best treatment conditions– concentration– temperature– time of MCP exposure– effective duration

1-MCP effects may be transient

Day 1

Day 2

Day 3

Plants were treated with 1-MCP on day 0, then exposed to ethylene on days 1, 2 or 3

Other growth regulators

• Gibberellins retard leaf yellowing

• So do cytokinins• Including thidiazuron, at

very low concentrations (5 µM)

Thidiazuron• A non-metabolized cytokinin analog• Mode of action not yet clear

– Reduced metabolism of native cytokinins?– Triggers the cytokinin response mechanism?

At higher concentrations (500 µM)TDZ improves Iris opening and vase life

Plus TDZ No TDZ

Can stimulate opening of a second flower

Cyclamen after 2 months display

Control TDZ

Food

• Flowers need food to grow and develop• Sugar (sucrose, glucose, or fructose)

provides all that is needed• Vase solutions should contain 1.5 – 3%

sugar• Bacteria like sugar too – use a

bactericide

Effect of sucrose pulse on Eustoma

Continued growth• Growth away from gravity• Growth towards light• Can cause quality loss

– snapdragons, tulip, red-hot poker• Control

– temperature– orientation– Chemicals

• Naphthylphthalamic acid• Inhibits auxin transport

Effect of NPA pretreatment

Acknowledgments

• USDA• BARD_Israel• American Floral

Endowment• Joseph H. Hill

Memorial Foundation• Mellano & Company• Kitayama Brothers• Goldsmith Seeds• Rosen Tantau