S05 - Session P1 - Application of exogenous gibberellic acid suppresses pigmented and unpigmented marginal picotee formations in cyclamen

Authors: Yuki Mizunoe *, Mei Igari, Yukio Ozaki

Cyclamen species are bulbous plants distributed in Mediterranean region, and their abundant cultivars are popular as a potted flower worldwide. Marginal picotee is one of the attractive floral characteristics that enhance ornamental value of the flower. Effects of plant growth regulators (PGRs) such as gibberellic acid (GA 3 ) and benzyladenine (BA) on floral shapes are well known, whereas ones on floral coloration including marginal picotee formation were not clarified. Present study was conducted to assess the effect of GA 3 and BA on marginal picotee formation in cyclamen. 'Victoria' and 'Hirari Bicolor' with red and white marginal picotee flowers, respectively, were used. The plants were cultivated in phytotron at 15℃, under relative humidity 70% and natural light, and all opened flowers were removed from the plants before treatments. PGR solutions, 2.5 and 5 ppm GA 3 , 50 and 100 ppm BA, were sprayed 10 mL each to leaf and corm surfaces, respectively, every 2 weeks. No spraying was conducted as control. Newly opened flowers were sampled every 2 weeks from 60 days after first PGR treatments. Flower stalk length, petal length, petal width and picotee width were measured. GA 3 treatments induced longer flower stalk and narrower picotee formations than control in both cultivars. In addition, GA 3 treatments produce longer petal than control in 'Hirari Bicolor'. BA treatments occasionally caused small sized petal and narrow picotee formations, while the effect was unstable. Although the effect of GA 3 on morphological characteristics were different depending on cultivars, application of exogenous GA 3 resulted narrow marginal picotee formation in both colored and uncolored marginal picotee cyclamens. Therefore, it was concluded that GA 3 suppresses marginal picotee formation irrespective of pigmented and unpigmented picotee flowers in cyclamen.