Sucrose Improves the Postharvest Life of Cut Flowers of a Hybrid Limonium

Regardless of their maturity at harvest, the vase life of cut inflorescences of the hybrid Limonium ‘Fantasia’ placed in deionized water was 4 to 5 days. A vase solution containing Physan (a quaternary ammonium disinfectant solution) at 200 μl•liter–1 and 20 g sucrose/liter not only prolonged the longevity of individual florets but also promoted bud opening so that the vase life of cut inflorescences extended to 17 days. Pulse treatment with 100 g sucrose/liter in combination with Physan at 200 μl•liter–1 for 12 hours partially substituted for a continuous supply of sucrose. Including 30 mg gibberellic acid/liter in the vase solution was without benefit. Table 1. Effects of continuous application of Physan at 200 μl•liter–1 with or without sucrose at 20 g•liter–1 on longevity of individual florets and inflorescences of hybrid Limonium ‘Fantasia’ harvested at three maturities (expressed as a percentage of open florets). Harvest Floret opening The Limonium cultivars Fantasia, Misty Blue, and Saint Pierre are interspecific hybrids between L. bellidifolia Gouan and L. latifolium Kuntzn. Under moderate growing temperatures (≈20C), the plants produce flower stalks bearing tiny blue flowers year-round. The panicled compound racemes comprise numerous subspikes containing eight to 12 pairs of flower buds. One of the flower buds in each pair develops earlier than the other. The opening of the more mature flower buds in each pair proceeds from the base to the top of the subspike; then the less mature buds in each pair open in the same sequence. During maturation, the color of the inflorescence changes from green to white and then to blue because the calyces are white and the petals blue. As petals wilt and inroll, the color turns back to white. The blue stage of the inflorescences, which is the most attractive in these hybrids, lasts for only a few days after harvest if the flowers are placed in plain water (A. Matsui, Matsui Nursery, personal communication). The short vase life of the cut inflorescences might reflect a failure in water relations or a failure of the unopened buds to develop. A similar situation occurs in cut gypsophila (Gypsophila paniculata L.), which also has numerous buds at different developmental stages. Marousky (1972) reported that effective flower opening, improved longevity, and increased turgidity was achieved in gypsophila by using a floral preservative containing 8-hydroxyquinoline citrate (8-HQC) and sucrose. The longevity of individual florets also was promoted by using a vase solution containing quaternary ammo1058 Received for publication 20 Jan. 1995. Accepted for publication 25 Mar. 1995. We thank Andy Matsui, Matsui Nursery, for donating the plant materials and Linda Dodge for her expert technical assistance. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact. 1On leave from College of Agriculture, Univ. of Osaka Prefecture, Sakai Osaka 593, Japan. nium compounds, such as Physan (Maril Products, Tustin, Calif.) (Van Doorn and Reid, 1992), benzalkonium chloride, or lauryl dimethyl ammonium bromide (Tandler et al., 1986). Adding sucrose to these solutions improved bud opening and further extended vase life of inflorescences (Farnham et al., 1978; Tandler et al., 1986; Van Doorn and Reid, 1992). Presumably, these disinfectants improve the water conductance by preventing bacterial growth (Van Doorn and Perik, 1990; Van Doorn et al., 1991), and sucrose supplies the energy and carbon skeletons required for bud opening. In contrast, Steinitz and Cohen (1982) reported that applying a combination of sucrose with silver nitrate as a biocide had no effect on flower bud opening in the most common commercial Limonium, L. sinuatum L.; however, they found that gibberellic acid (GA3) was effective in promoting petal expansion. Therefore, our objectives were to examine the effects of bactericides (Physan and 8HQC), sucrose, and GA3 on the longevity of the hybrid Limonium ‘Fantasia’ to develop a useful commercial means of extending the life of these attractive flowers. Materials and Methods Inflorescences of hybrid Limonium ‘Fantasia’, harvested with 5%, 15%, and 40% of their florets open, were harvested from a com-