Ornamental Industry. The postharvest problems. Value of California s agriculture. Postharvest science 6/19/2013

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1 Ornamental Industry Floriculture crops : cut flowers, cut cultivated greens, foliage plants, potted flowering plants, annual bedding/garden plants, propagative floriculture materials Cai Zhong Jiang, USDA ARS, Davis Michael Reid, University of California, Davis Nursery crops : Evergreens_broadleaf, Trees_shade, flowering, Christmas trees, fruit and nut plants, transplants, shrubs and other ornamentals and propagation materials Value of California s agriculture Data from the California Department of Food and Agriculture. 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 Postharvest science Goal reduce losses, increase quality, expand markets Understand factors involved in postharvest losses Develop better technologies to reduce losses Factors affecting the postharvest life of ornamentals Temperature Disease Water supply Ethylene and other PGRs Food supply Biotechnology 1

2 Temperature why is it important? Effect of temperature Lilies stored 5 days, 2 days in vase life room Perishable products are alive Flowers have high respiration rates Vase life is directly correlated with the respiration rate Improving the cold chain Transportation at low temperatures reduces respiration & improves the subsequent life of cut flowers Respiration (m l CO 2 / kg hr) Temperature, respiration rate & vase life in stock flowers y =.12x x x x R 2 = Temperature (C) Vase life after storag e ( d a y s ) y = -.299x R 2 = Total CO2 respired during storage (x1) m l CO2/kg Temperature Effects on potted Campanula plant quality Variety 1 after 7 day shipment 2

3 Number per inflorescence C Room Effects of storage temperatures on performance of Campanula 2 C 15C 1 C 5 C C Wilted flowers Fresh flowers Fresh buds Aborted buds Advantages of decreased temperature in handling flowers 1. respiration 2. transpiration 3. dehydration 4. ethylene production 5. ethylene susceptibility 6. condensation 7. disease growth (Botrytis) 8. bending 9. flower development 1. color loss/yellowing Forced air for cut flowers Cooling Vacuum cooling: a better approach to rapidly cool down potted plants The rapidity of vacuum cooling in less than 1 min vacuum Flower buds Postharvest Disease Postharvest disease (primarily caused by gray mold (Botrytis cinerea) is a common cause of poor quality and shortened vase life Soil & stems 3

4 Botrytis cinerea The lifecycle of Botrytis cinerea Ubiquitous and necrotrophic fungus Affects numerous agricultural crops Causal agent of gray mold disease Brings about severe economic losses Pre harvest and postharvest infection 5. Sporulation 1. Spore 2. Germinating conidia 3. Entry 4. Proliferation Disease control strategies Disease control The disease life cycle Pathogen Environment Disease Host Reduce spore load o sanitation in field, greenhouse, shed Prevent spore germination o reduce condensation, injury, temperature Prevent fungal entry o care in handling The disease triangle Disease control Temperature Humidity o prevent condensation Atmosphere o high CO 2, CO/low O 2 Fungicides Rely on synthetic chemical fungicides Effective Applied by dipping, in fogs Development of resistance Safety & environmental concerns 4

5 Alternative or Non Conventional Chemical Control: Where do we look for possibilities? FDA Generally Recognized as Safe (GRAS)/ generally recognized as safe and effective (GRASE) Plant Defense Compounds 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 Optimal concentration of sodium hypochlorite for controlling botrytis on rose Akito and Gold Strike flowers Optimal treatment time of sodium hypochlorite for controlling botrytis on rose Gold Strike flowers Botrytis incidence (%) a a 'Gold Strike' 1 a a 'Akito' b 2 b b b b b b b No dip NaOCl concentration (µl L -1 ) Flowers were dipped in, 1, 2, 4 or 8 µl L 1 (ppm) NaOCl (provided by Clorox Ultra bleach solution) for 1 s. Botrytis incidence (%) 1 Water a a NaOCl 8 a a a a b b b b Dip treatment time (s) Flowers were dipped in (water) or 2 µl L 1 (ppm) NaOCl (provided by Clorox Ultra bleach solution) for 1, 5, 1 or 3 s at 2 C. Botrytis Spore Germination and Treatment Timing Using NaOCl to control Botrytis infection in cut rose Hypothesis: Timing of postharvest dip treatment influences its effectiveness because of treatment interaction with spore germination process. Botrytis score, day H2O oxidizer P Hours before dipping Spore germ tube development 2.5 hours after suspension in free water. 5

6 Water supply Plants are mostly water (8 9%) Loss of water causes loss of quality wilting accelerated aging (ethylene production) Water supply How do plants get water? Evaporation from leaves (transpiration) creates tension in the conducting system (xylem) Tension drags water from the soil or vase solution Water supply Why do cut flowers wilt? Air embolism Bacterial contamination Why do potted plants wilt? Drought Waterlogging Air embolism blocks vessels 6

7 Maintaining water supply Vertical water packs Proconas Use a preservative Clean white buckets The simple question: Would you No drink ClO 2 that water, Plus ClO 2 from that bucket? An Alternative Postharvest Handling Strategy for Cut Flowers Dry Handling after Harvest Potted plants_water stress 25 No hydration Vase life (days) Plus Hydration 5 Black Magic Charlotte Freedom Osiana Vendela H 2 O saturation+ 6 ppm surfactant Combination strategies Chemical Manipulation of ABA Level Vacuum cooling ABA + water spray Precooling effect ABA? Refrigerator transportation ABA? Surfactant effect Well watered NaCl ABA Not Watered 7

8 Application of ABA enhances display life of potted miniature rose plants Increasing ABA accumulation enhances drought tolerance in petunia Drought treatment, day 15 Transgenic Control Increasing ABA accumulation enhances drought tolerance in petunia Transgenic 1 days after re watering Control Carnation Ethylene dependent Ethylene production prior to onset of natural senescence Pollination accelerates ethylene production and senescence Response to ethylene treatments Rose plants were initially stored at C for 7 days and then treated with 2.5 ppm of ethylene for 48 hours. Pre treatments Specialized treatments Silver thiosulfate (STS) 1 methylcyclopropene (1 MCP) 8

9 STS Benefits of 1 MCP Applying 1 MCP Alternative mode of delivery And the sachets work for potted plants too! Plus sachets No sachets Using biotechnology to block ethylene signaling The mutant receptor, etr1-1, identified from Arabidopsis has been shown to be unable to bind ethylene and confers ethylene insensitivity. Expression of Arabidopsis etr1-1 in other species, including carnation, leads to delayed floral senescence. 9

10 Other growth regulators Gibberellins retard leaf yellowing So do cytokinins Including TDZ (thidiazuron), a nonmetabolized cytokinin Effect of TDZ on a range of flowers Continuous treatment with 1 M TDZ. Plus TDZ No TDZ Photographs after 7 to 1 days Can stimulate opening of a second flower Left, Control, Right, TDZ. Effect of TDZ on cyclamen 2 months in vase life room Use of TDZ to prevent leaf yellowing and extend flower life in Freesia TDZ+MCP TDZ MCP+Ethylene MCP Control+Ethylene Control Control TDZ TDZ treated Control Food 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 1

11 Sugar pulsing to provide food Effect of sucrose pulse on Eustoma Factors affecting the postharvest life of ornamentals Temperature Disease Water supply Ethylene Food supply QUESTIONS? Biotechnology 11