S05 - Session P1 - Early water absorption in petals causes malformed flower in rose variety `Yves Piaget´

Authors: Rei Kaneeda *, Takashi Handa, Toru Hirose, Chie Yoshida

In roses, malformed flowers are often generated before and after harvest, affecting cut flower production. Malformed flower symptoms vary depending on flower variety and cultivation. Some double flower varieties, such as fragrant rose 'Yves Piaget' often produce malformed flowers with petals that curve toward opposite axis. These malformed petals prevent normal flowering and weaken fragrance emission in this variety. We termed this malformed flower as "incurved flower." Our previous studies (Acta Hortic. 1263. ISHS 2019. DOI 10.17660) have revealed differences in acid invertase activities and carbohydrate content of petals between incurved flower and normal flower; however, water absorption in petals has not been fully investigated. In this study, we investigated fresh weight, water uptake, water potential, osmotic potential, and turgor pressure before and after harvest. Fresh weight of petals of incurved flower was significantly heavier than that of normal flower before harvest, but there was no significant difference in dry weight. These results indicate that water absorption is earlier in incurved flower than in normal flower before harvest. Water absorption of incurved flower on day 0-2 after harvest was significantly higher than that of normal flower, but maximum flower diameter of incurved flower was smaller than that of normal flower continuously after harvest. Water potential of petals in incurved flower was significantly higher than that of normal flower on day 0-3 after harvest. Calculated values of petal turgor pressure tended to be higher in incurved flower than in normal flower on day 0-1, but reversed on day 2. These results suggest that water absorption of petals in incurved flower is considered to be inhibited, and this could be due to early water absorption before harvest. From our finding, regulation of water potential supposed to be important to suppress malformed flower.