Ornamentals Flashcards
Cut flowers end of vase life
Senescence • Botrytis • Bent neck / stem break • Flower/leaf wilting • Turbid and smelly water • Leaf yellowing / blackening • Stem blackness • Petal discoloration • Flower disc discoloration • Impaired flower opening
Potted plants end of shelf life
Flower senescence / flower drop • Leaf drop • Leaf discoloration • Chilling injury • Ethylene effect
• Cuttings quality problems
- Bad rooting
- Wilting
- No shooting
- Wound response
- Ethylene and other hormones
- Plant physiological processes
What causes turbid water?
- bacteria - botrytis
- disbudded flower : there is abundance of sugar so the bacteria can grow better -> more turbid water and also faster than spray flower(low shelf life)
Ideal cut height of flowers for better vase life
> 25 cm cut above the soil -> increase the fresh weight during vase life
Carbohydrate leakage
What happens when you increase storage of cut flowers?
- increase storage sugar in the stems -> with chilling injuries (low T) membranes break -> increase the sugar in the water -> bacteria growth in the vase (turbid water)
- disbudded flower have higher amount of sugars compared to spray flower so they have less carbohydrate starvation therefore extended vase life
Hormones. How do they affect postharvest life of flowers
- Cytokinin improves potted cyclamen -> reverse senescence -> makes juvenile tissues again
- ABA improves desiccation in miniature roses
- ethylene leads to flower drop
Disease / pest
- Botrytis on cut flowers
* Powdery Mildew etc. etc
How water uptake blockage can happen?
- bacterial blockage
- air emboli
- enzymatic wound response
Bad water balance -> end of vase life (stem break)
Fresh weight -> quality assesment
Solutions to deteriorate water balance
• Cut of the infected part Can only move up the stem up to the pith membrane • Use biocides (and clean water) Bleach, DICA, HQS, Al2(SO4)3 • Keep everything cold Bacteria grow slower at low temp
Solutions to deteriorate air emboli
* it is caused by air shoots in xylem vessels and by negative pressure
- Cold water lowers change for air emboli
- Solubility of air is higher in cold water
- Detergent to lower surface tension
PAL enzyme inhibitor
Stress response can lead to blockages • Inhibiting stress enzyme such as PAL reduces blockage • Cut and recut as little as possible • Low temperatures reduce wound response
What happens with high relative humidity ?
1) -saves energy
- reduced keeping quality
2) stomata mulfunctioning they lose the ability to close if they have a long exposure to high RH which leads to a negative water balance and early end of vase life
Why do we add Postharvest additives immediately after harvest ?
- Decrease bacteria
- Avoid air emboli
- Suppress wound response
- Prevent carbohydrate starvation
