Lilies and gladioli are among the most important cut flowers grown throughout the world. However, leaf chlorosis is a major postharvest disorder that can limit their vase life. The chlorosis starts on lower leaves and proceeds upward, reducing stem quality and causing early senescence. This problem is accentuated by shipping or cold storage, resulting in early leaf wilting or abscission (Han, 2001). But storage or shipping at low temperatures is necessary for transportation and marketing of cut stems to distant markets. Fluctuations in temperature during shipping/storage or transit time greatly affect cut lilies and loss of quality starts quickly when stems are placed in the retail or consumer environment after transit/storage. Additionally, cultivars vary in exhibiting leaf chlorosis symptoms (Leonard et al., 1998).
Use of gibberellins and cytokinins effectively controlled leaf chlorosis of calla lily [Zantedeschia aethiopica (Skutnik et al., 2001)], narcissus [Narcissus tazetta (Ichimura and Goto, 2000)], goldenrod [Solidago canadensis (Philosoph-Hadas et al., 1996)], and alstroemeria [Alstroemeria sp. (Hicklenton, 1991)]. Continuous vase application at 0.5 and 2.5 mg·L−1 each of gibberellin and cytokinin or short-term 4-h pulse at 25 mg·L−1 controlled leaf chlorosis of cut oriental and asiatic lilies. However, continuous application enhanced bud blasting (Han, 2001). Similarly, mode and time of application of PGR also affected leaf chlorosis of lilies and various cultivars of potted oriental hybrid lily or easter lily (Lilium longiflorum) responded differently, depending on the mode of application (Çelikel et al., 2002; Han, 1997; Ranwala and Miller, 2000). Several commercial formulations of gibberellin plus benzyladenine have also been tested for preventing leaf chlorosis, such as Provide or Promalin (Abbot Chemical Co., North Chicago, IL) and Fascination (Valent BioSciences Corp., Libertyville, IL) (Han, 1997, Leonard and Nell, 2004). Gibberellin controlled leaf chlorosis more effectively than just benzyladenine (van Doorn and Han, 2011). Among commercial floral preservative products, a proprietary mixture of GA4+7 plus BA in a commercial floral preservative (Chrysal BVB; Chrysal, Miami, FL) controlled leaf chlorosis of lilies, but a proprietary mixture containing gibberellin (Chrysal SVB), did not (Leonard and Nell, 2004). However, the proprietary mixture containing gibberellin was effective for prevention of leaf chlorosis in christmas bells [Sandersonia aurantica (Eason, 2002)].
Although several studies on use of different concentrations and application methods of gibberellins and cytokinin have been conducted on cut lilies to control leaf chlorosis, limited information has been reported on pulsing at low concentrations under low temperature used commercially for transportation or storage of cut lilies. Moreover, to our knowledge, no study is reported on effect of gibberellins and benzyladenine on postharvest performance of cut gladiolus. Therefore, the objectives of this study were to evaluate the effects of a new plant growth regulator proprietary product, GA4+7 + BA (Fresco; Fine Americas, Walnut Creek, CA), on leaf chlorosis and vase life extension, and to compare the effects of different concentrations of GA4+7 + BA with GA4+7 + BA + preservative or a propriety mixture of sugar plus acidifier developed for bulbous flowers [floral bulb preservative (Chrysal Bulb Flower Food)] on postharvest quality and leaf chlorosis of cut lilies and gladioli.
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