Presentation on theme: "Postharvest handling of cut flowers"— Presentation transcript:
1Postharvest handling of cut flowers Advanced Course onPostharvest TechnologyNovember 2003, MauritiusDr. Ron PoratDept. of Postharvest Science of Fresh ProduceARO, The Volcani Center, Bet Dagan, Israel
2Among horticultural crops, cut flowers have perhaps the highest commercial value but are most perishable: they loose a lot of water, have high respiration rates, and are susceptible to physical damage.
3Factors affecting postharvest longevity and quality of cut flowers Maturity stageCarbohydrate supplyTemperatureWater lossEthyleneMechanical damageDiseases
4Maturity stageCut flowers are usually picked when the buds are starting to open. (rose, gladiolus).In some cases, the flowers must be picked open (chrysantemum, carnation).
5Carbohydrate supplyThe reserves of starch and carbohydrates in the leaves and stems are usually not enough to support energy for proper bud opening and maintenance.Therefore, cut flowers are often pulsed for up to 24 h with a solution containing sugars (from 2 to 20% sucrose).Control5% SucroseLiatris
6TemperatureFlowers have high respiration rates, which increases logarithmically with increasing temperatures.Cooling slows respiration and delays senescence.The optimal storage temperatures for most cut flowers are between 0-2ºC.Tropical flowers, like anthurium and several orchids, that are sensitive to low temperatures should be kept at 10-13ºC.
8Water lossFlowers have a large surface area and, therefore, they loose water rapidly.Flowers should be stored at low temperatures and at a relative humidity of 95% to reduce water loss and wilting.The main causes for problems in water uptake are:Air embolism: occurs when bubbles of air are drawn into the stems at the time of cutting.Air bubbles can be removed by re-cutting the stem.Bacterial plugging: Growth of fungi and bacteria can plug the water transpiration system. To avoid this, holding solutions should be acidic (pH 3.5) and contain germicides.
9Ethylene Many flowers perish rapidly in response to ethylene. Carnations, orchids, etc. – ethylene induces senescenceSnapdragon, delphinium, etc. - ethylene induces abscissionIt is important to avoid pollution with ethylene, to remove ethylene from storage rooms by ventilation, and to treat the flowers with ethylene action inhibitors (STS, 1-MCP).
10Mechanical damageBruising and injuries are undesirable from an aesthetic point of view, but also provide pathogen invasion sites.The cut flowers must be wrapped carefully and be protected by polyethylene sleeves, shredded paper, etc.
11DiseasesDecay, especially gray mold caused by Botrytis cinerea, provides a major cause for postharvest losses.The cut flowers should be kept at low temperatures without water condensation.
12Effect of combined treatment of pulsing and spraying with TOG-MJ-1 on appearance of various cut rose cultivars following artificial infection with Botrytis(Spraying with 0.6% TOG-MJ-1 / pulsing with 0.4% TOG-MJ-1)Red CharmControlTOG-MJ-1B.FriscoControlTOG-MJ-1C.Pink TangoControlD.TOG-MJ-1ControlTOG-MJ-1E.TamaraCarmenControlTOG-MJ-1A.Sun BeamTOG-MJ-1F.Control7 days in vase life
13Postharvest handling of cut flowers GradingBunching and sleevingChemical pulse treatmentsPackingCoolingDry or wet storageTransportationMarketing
14Postharvest vase solutions Vase solutions typically contain:Low concentrations of sugar (0.5-2%)A biocide [usually hydroxyquinoline (HQC) or TOG]Citric acid (300 ppm) to keep a low pH.
15Handling requirements of some representative cut flowers Anthurium* Storage at 10-12C.* Prevent mechanical damage by wrapping with plastic sleeves and fill-packing boxes with shredded paper.
16RosesPulse treatments with fungicides (vinclozolin, iprodione, copper) against Botrytis cinerea.Storage at low temperature (0-2C) without water condensation.Usually, not treated with sugar or ethylene inhibitors.Add bleach to the vase solution.
17Gerbera Are long lasting (till 20 days). Add bleach to vase solution Trim stems every few days
18LiliumPulse treatment with GA and STS.Add bleach to vase solution
19GladiolusPulse with high concentrations of sugar (10%), STS and a fungicide.