Dormancy and sprouting in gladiolus

The onset, level and disappearance of dormancy in corms and cormels of summer- flowering gladiolus cultivars were studied in relation to environmental conditions and revaluated as an ecological adaption. The cormels were more deeply dormant than their sister corms, which were most dormant when formed at higher temperatures and in longer photoperiods. The depth of dormancy therefore varied from year to year and from cultivar to cultivar. Dormancy disappeared during dry storage at all temperatures between 6° and 27°C but quickest at 6° or 10°C. These low temperatures were essential to keep cormels out of dormancy. Dormancy was not broken at any single temperature in moist soil; temperatures alternating between 10° and 22° were necessary. Sprouting of the cormels varied with the state of their shell and size. No correlation was found with respiration although CO ₂ production of cormels with broken shells was 6-16 times as high as in intact cormels. The different depths of dormancy at planting were maintained throughout a long period in moist soil at 20°C. Plants grown from cormels stored at different temperatures produced the same numbers of corms and cormels, if the plants were the same age and were spaced alike.