New cut flower introductions are a necessity to maintain and increase consumer interest. Expanding the availability and knowledge of new cut flowers allows growers to pick species ideally suited for their climate and consumer base. Many garden ornamental species are underused by the floral industry, such as beardtongues (Penstemon sp.). Large-flowered beardtongue (P. grandiflorus) has the largest flowers and the greatest color range (31 different distinct color shades) of all beardtongue species (Way and James, 1998). Current cultivars being produced as cut flowers have much smaller flowers that are muted pink, purple, or white in coloration. ‘Esprit’ penstemon (Fig. 1) would offer growers a showy, vibrant colored flower mix. New cultivars and species may appear to have potential, but growers are hesitant to produce new cut flower crops without information on production and postharvest techniques.
Determining the age at which a young plant can be transplanted successfully is essential to obtain quality plants and reduce production costs (Cavins and Dole, 2001; van Iersel, 1997). Although it may be more economical to leave plants in plug trays for as long as possible before transplanting to the final production area to allow a greater number of crops to be harvested in a season, prolonged duration in the plug flats can stunt growth and cause plants to have fewer, shorter, or thinner stems that do not produce quality flowers due to excessive root restriction (Donnell, 2006; van Iersel, 1997). It is also important for growers to know optimal production temperatures before growing a new crop. Each plant species has a range of temperatures that are tolerable and allow plant growth, but extreme temperatures within that range can stress plants resulting in pest/disease problems, unacceptably long production times, or reduced inflorescence quality (Dole and Wilkins, 2005).
A number of factors influence vase life after harvest, including ethylene, storage temperatures, sucrose pulses, and commercial preservatives. Ethylene exposure can have deleterious effects on cut flowers. Selected species of beardtongue are sensitive to ethylene, including foxglove beardtongue (P. digitalis), which results in flower abscission and reduced vase life (Redman et al., 2002). Treating cut stems with 1-methylcyclopropene (1-MCP) or silver thiosulfate (STS) has been shown to reduce the negative effects of ethylene exposure on some cut flower species (Dole and Wilkins, 2005).
Cooling retards the utilization of carbohydrates during respiration, which extends postharvest life and delays development in most species (Sacalis, 1993). A desirable quality of a cut flower is the ability to be shipped long distances out of water (dry) without an adverse effect on vase life. Despite the benefits of cold and dry storage, some flower species do not respond well.
Pretreatments are used to extend vase life and are applied before holding in floral preservatives (Hunter, 2000). Sucrose pulses are a pretreatment used to increase vase life by loading stems with sugar to facilitate the storage of carbohydrates before they are dry packed and shipped long distances or held in storage for long periods of time (Hunter, 2000; Nowak and Rudnicki, 1990). Effective concentrations depend on the species and can have variable effects (Mohan Ram and Ramanuja Rao, 1977), but generally range anywhere from 1% to 20% (Dole and Wilkins, 2005).
Commercial preservatives extend the vase life of many species, but may have no effect on others (Sacalis, 1993). Typically, floral preservatives can be categorized as hydrating, holding, or vase solutions. Holding solutions contain a carbohydrate source to encourage bud opening and/or flower longevity and are applied for ≈1–2 d. Hydrating solutions are meant to be applied before a holding solution right after harvest for ≈4 h to facilitate water uptake and do not contain a carbohydrate source (Dole and Wilkins, 2005). Vase solutions are generally applied by the consumer and contain a lower concentration of carbohydrates than a holding solution. The ability for new cut flowers to perform well in floral foam is also important, especially to floral designers.
The objectives of this study were to determine optimal production temperature, transplant stage, and postharvest procedures, including commercial preservatives, ethylene sensitivity, sucrose pulses, and cold storage for ‘Esprit’ penstemon to be considered for use as a new cut flower introduction.
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