Miniature Gladiolus Cultivars Bred for Winter Flowering

Abstract

Most of the commercial gladioli in the world have been bred to provide cut flowers in the summer. Growing these cultivars in subtropical and Mediterranean climates during the winter months frequently results in low-quality flowers (Halevy, 1985; Magic and Cowperthwaite, 1954; McKay et al., 1981; Shillo and Halevy, 1976a). The failure to grow high-quality gladiolus flowers during the winter months has been attributed to the sensitivity of these summer cultivars to low light intensities (Shillo and Halevy, 1975, 1976b), short photoperiods (Shillo and Halevy, 1976c, 1981), and the combined effect of low irradiance with low night temperatures (Halevy, 1985; Shillo and Halevy, 1963) during flower development. The European restriction on the importation of cut flowers to the winter months generated the need to develop gladiolus cultivars selected to produce high-quality flowers under winter conditions. [In December, the average daylength in Tel-Aviv, Israel, is 10 h and 5 rein, with an average irradiance of 850 to 1000 μmol·s ·2 (400-700 nm).] In addition, the flower industry required a smaller, lightweight flower able to respond favorably to higher density planting, produce higher yields, and reduce shipping costs. In response to the demands of the cut flower industry and the renewed interest in smaller cultivars (Barnard, 1972; Halevy et al., 1984), a new group of miniature gladiolus was developed for the cut flower market. Their main properties are: winter flowering, light weight, and attractive variety of colors. The group was nicknamed ‘Orchidiola’ (orchid glads) by the Israeli flower industry. The name was inspired by the petal shape and the variation