Ornamentals and Cut Flowers

Abstract

CONTENTS 19.1 Introduction 491 19.2 CA and MA Storage of Cut Flowers and Greens 49319.2.1 Anthurium 493 19.2.2 Carnation 494 19.2.3 Daffodil 495 19.2.4 Gladiolus 495 19.2.5 Rose 496 19.2.6 Foliage Plant Species 49619.3 CA and MA Storage of Bulbs 496 19.3.1 Lily 496 19.3.2 Tulip 49719.4 CA and MA Storage of Vegetative Cuttings 498 19.5 CA and MA Storage of Potted Ornamental Plants 498 19.6 CA and MA Treatments for Pest and Disease Control 498 19.7 Biotic and Abiotic Factors Affecting the Efficacy of CA and MA Treatments....... 500 19.8 Future Research Needs and Commercial Applications 502 19.9 Conclusions 503 References 503Ornamental plants and their detached organs (e.g., bulbs, cut flowers) are among the most highly perishable horticultural commodities traded internationally (Reid, 2002). High rates of respiration and transpiration, sensitivity to ethylene, and=or low natural resistance to disease-causing organisms (e.g., Botrytis cinerea) often limit the postharvest life of ornamentals (Elad, 1988; Reid, 2002). Extending the time that these products can be stored would provide an opportunity to use less expensive surface (e.g., truck, boat) transport than the current costly reliance on airplanes to supply international markets. Developing appropriate methods of storing ornamentals, particularly cut flowers, could also facilitate product accumulation and distribution for more profitable marketing on special days (e.g., Valentine’s Day, Mother’s Day) when demand for these commodities often exceeds supply. Storing ornamental plants at low but nonchilling and nonfreezing temperatures isan effective method for extending postharvest life (Halevy and Mayak, 1981). LowTABLE 19.1Published Studies that Have Evaluated Responses of Ornamental Plants and Their Detached Organs to CA and MA Treatmentstemperatures reduce rates of respiration, ethylene production and sensitivity, and metabolic reactions associated with tissue senescence (Barden and Hanan, 1972; Maxie et al., 1973). Maintaining ornamental commodities at constant optimal storage temperatures also prevents condensation from developing on tissues and thereby reduces the related development of fungal pathogens (Reid, 2002). A range of chemical treatments including antiethylene agents (e.g., silver thiosulfate [STS]), hormones (e.g., cytokinins) and fungicides (e.g., iprodione) are also used to maximize the postharvest life of ornamentals (Halevy and Mayak, 1981). Exposure to atmospheres of reduced O2 and=or elevated CO2 concentrations is anadditional strategy with potential to maintain the postproduction longevity of ornamentals. Storage under such an appropriate controlled atmosphere (CA) or within packaging in which a beneficial modified atmosphere (MA) develops is an effective means for extending the postharvest longevity of various fruits (e.g., apple, pear) and vegetables (e.g., broccoli) (Kader et al., 1989). The benefits of CA principally arise from associated reductions in rates of respiration, ethylene production and response, and oxidative processes (Beaudry, 1999). CA treatments can also aid in reducing pest infestations (e.g., arthropods) and disease infections (e.g., Botrytis) of harvested commodities (El-Goorani and Sommer, 1981; El-Kazzaz et al., 1983). In contrast to fruits and vegetables, effects of CA storage and MA packaging (MAP) on ornamentals have been less extensively and intensively studied. Thus, relatively few ornamental plant species have been tested for beneficial effects of CA and MA treatments (Table 19.1). Nonetheless, early studies on CA storage of cut flowers date back to 1930 (Thornton, 1930). Some interesting studies have also evaluated hypobaric storage, whereby a reduction in atmospheric pressure reduces the partial pressure of O2 and other gases (e.g., ethylene) and can extend the longevity of ornamentals (Dilley et al., 1975; Staby et al., 1982). The principles and effects of CA and MA treatments on ornamentals have previouslybeen well documented by Halevy and Mayak (1981), Eisenberg (1985), Goszczynska and Rudnicki (1988), and Zagory and Reid (1989). This chapter aims to highlight specific examples of ornamental species that have responded favorably to CA and MA in terms of extended storage life, including reduced insect pest and fungal pathogen problems. Key biotic and abiotic factors affecting the efficacy of CA treatments and opportunities for future study and commercial development are also discussed.