Successful cut flower production depends on the ability to produce crops economically in a short, predictable amount of time. Profitability of a cut flower cultivar relies on market price, yield of long, strong, and easy-to-harvest stems, manageable insect and disease pressures, short crop cycle, and long postharvest life (Armitage and Laushman, 2003; Bridgen, 1992). Few cultivars have all these characteristics. Common problems include unacceptably short stems, long production times, or lengthy flower-initiation procedures. Growers may be able to alleviate some of these issues by applying gibberellic acid to their crops.
Gibberellic acid can be used to break dormancy, promote stem elongation, and replace photoperiodic requirements (Kende and Zeevaart, 1997; Pharis and King, 1985; Sharma and Kumar, 2005; Wittwer and Bukovac, 1957). Examples of cut flowers that are treated with GA3 during production include lisianthus (Eustoma grandiflorum) to prevent rosetting and shorten production time (Jie et al., 2003; JongWon et al., 2000), calla lily (Zantedeschia albomaculata) to increase the number of flowers and shorten production time (Ball, 1991), and species in which GA3 can be used to break dormancy such as liatris (Liatris spicata), monkshood (Aconitum napellus), and peony (Paeonia suffruticosa) as reported by Wanjao and Waithaka (1983), Lurie et al. (1992), and GuoSheng et al. (2009), respectively. With other species, such as cut poinsettia (Euphorbia pulcherrima), tall stems can be produced without GA3, but using the growth regulator can produce the desired height in a shorter time period (Hartrath, 1987). Three benefits were achieved by treating perennial aster (Aster ericoides) with GA3: breaking dormancy, increasing stem length, and reducing production time (Naranja and Balladares, 2008).
Because GA3 effects can vary greatly among different taxa, the objective of these trials was to quantify the effects of GA3 on cut stem production in 13 field-grown, cut flower cultivars: ageratum (two cultivars), celosia, delphinium, foxglove, larkspur, lobelia, ornamental pepper, stock, sweet william, dianthus (two cultivars), yarrow, and zinnia.
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