Postproduction losses are an important financial constraint in the floriculture industry. Loss estimates of 5% to 30% per year have been made (Armitage, 1993; Healy, 2009; Jones, 2002; Staby et al., 1978). Losses can occur at many levels from the moment plants leave the production facility until plants are sold to the consumer. Floricultural crops, including many potted plants and bedding plants, are often shipped significant distances in dark trucks that may or may not have adequate temperature control. Losses can be attributed to water stress (especially in the retail environment), damage by mechanical means (vibration, abrasion, breakage) and by ethylene, which may be present exogenously in the shipping chain or could be produced directly by plants and flowers during the stress of transport. In the absence of adequate temperature control, warm temperatures during transport will potentially increase endogenous ethylene production and will increase sensitivity to ethylene whether exogenous or endogenous in nature. In many floriculture crops, ethylene results in flower, bud, or leaf abscission, epinasty, and hastening of senescence (Gibson et al., 2000; Reid and Jiang, 2012).
Skog et al. (2001) measured ethylene levels in midsize to large wholesale and retail businesses in Ontario, Canada. Detectable levels of ethylene (>0.01 μL·L−1) were measured in 63% of air samples and these levels ranged from 0.01 to 10 μL·L−1. Sources of ethylene included fresh or rotting produce, propane exhaust, smoke, gas-fired heating equipment, leaks from ethylene rooms used for gassing produce, and recently gassed produce. Areas that contained only flowers and had no produce on the premises exhibited ethylene concentrations ranging from undetectable (<0.01) to moderate (1.44 μL·L−1). Loading areas should be kept separate from active growing plants and within these confined areas there is a need for ample ventilation, proper maintenance of equipment, and removal of plant debris to reduce ethylene contamination.
As it is unlikely to completely remove ethylene from the postproduction chain, a significant effort has been placed into technologies to reduce the effect of ethylene on floriculture crops. 1-MCP binds to ethylene receptor sites on the plant and with proper application will render plants unsusceptible to endogenous and exogenous ethylene for a period depending on plant growth (Blankenship and Dole, 2003). Current use of 1-MCP in floriculture is limited to a gaseous application sold under various names (EthylBloc; Floralife Inc., Walterboro, SC and Ethylene Buster; Chrysal Intl., Naarden, The Netherlands). With this technology, plants are enclosed in a sealed chamber (treatment room or sealed delivery truck) and the gaseous 1-MCP is released from the commercial powder with a wetting agent. The area must remain sealed for a specified time. This treatment method can be limiting to postproduction efficiency and convenience because plants or flowers must be enclosed in the 1-MCP atmosphere from 4 to 10 h to achieve full protection from ethylene (Jones and Edelman, 2013; Reid and Çelikel, 2008). Other release mechanisms include 1-MCP sachets that are dipped in water and placed into shipping boxes, a technique especially useful for boxed cut flowers or potted plants (Jones and Edelman, 2013).
In the last few years, a sprayable formulation of 1-MCP (AFxRD-038; Rohm and Hass, Philadelphia, PA) has been registered for in-orchard use on fruit (apples, pears, and kiwifruit) and field crops (sunflower, wheat, and rice) as Harvista™ and Invinsa™. While the sprayable formulation has gained a significant presence in these crops, it is not currently registered for use on floriculture crops, and information on its use in greenhouse settings is limited.
Impatiens plants are highly sensitive to ethylene and show rapid flower abscission (overnight) when exposed to very low concentrations of ethylene (Dostal et al., 1991). Both Impatiens ×hawkeri (Dostal et al., 1991; Han, 2003) and I. walleriana can benefit from 1-MCP protection to improve postharvest quality (Han, 2003; Skog, 2001). Impatiens, therefore, can serve as an excellent model plant to investigate the use and efficacy of this novel 1-MCP formulation on floral crops.
The objective of this work was to investigate parameters associated with the use of a sprayable formulation of 1-MCP (as AFxRE-038) on Impatiens plants. Concentration, timing of application, spray volume, pH of spray solution, mixing and storage, overhead irrigation, and duration of protection against exogenous ethylene were investigated.
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