Effect of day length and corm storage temperature on flowering Gladiolus tristis sbsp. concolor

Gladiolus tristis sbsp. concolor is an ornamental plant widely sold in local markets in SE Spain. Various studies have accumulated information on the characteristics of the floral stem, from its aroma to its potential alternative as a cut flower. The objective of this work was to evaluate the floral behaviour of gladiolus plants, generated by corms of small calibre (<5), exposed to chilling at 5°C for 2,3,4 and 5 weeks under wet conditions; subsequently, half of the chilled corms were kept under natural short day (SD) conditions and the other half were exposed to long day (LD) conditions. When grown from small corms, this subspecies possesses two sprouts per corm. The length of the first and second leaf in the first sprout was bigger than the corresponding organs in the second sprout after exposure to LD conditions, the reverse being true when the plants were grown with natural light. Stem diameter was greater in the first sprout after the application of supplementary light. LD had a significant effect on flower development and flower quality, this treatment resulting in the largest flower, longest spike and the most florets per spike. The same plants flowered significantly earlier than plants under SD conditions (96 days after planting, as opposed to 109 days). In terms of production, the low temperatures applied during the corm storage period had a bigger effect on the yield than the LD conditions.