Changes in carbohydrate content in petal parts of incurved malformed flowers of fragrant cut rose cultivar 'Yves Piaget'
Rosa ×hybrida Yves Piaget is a fragrant cut rose cultivar that sometimes bears malformed flowers designated as incurved flowering. This incurved flowering is characterized by adaxial curving of the petals, which decreases emission of volatile compounds. However, incurved flowering physiology is not clear. In this study, we compared fresh weight, and contents of carbohydrates in petal parts and leaf of both normal and malformed flowers. The flowers were harvested at three different flowering stages: stage 1, tight bud; stage 2: mature bud; stage 3: five opened petals. They were cut into pieces at less than 1 cm using edge and other part of the petal. Their fresh weight and growth rate was measured and calculated. Five outer petals were used to analyse carbohydrate content by HPLC. The rate of fresh weight was increased at stage 2 in all parts of both normal and malformed flowers, and the growth rate of malformed flowers were higher than that of normal flower. However, at stage 3, growth rate in the edge of the petal of malformed flower was decreased. The fructose content in the edge of malformed flower petals was lower compared to normal flowers at stage 2 and 3. The other part of the petals showed no difference in carbohydrate contents between normal and malformed flowers at all stages. These results suggest that fructose level in the edge of malformed flower petals decreased osmotic pressure that enabled water flow into the petal cells. We have concluded that water may not have been able to flow into the immature cells of the edges of the petals and may have caused the adaxial curving of the petals in malformed flower.
Kaneeda, R., Yamamoto, S. and Handa, T. (2019). Changes in carbohydrate content in petal parts of incurved malformed flowers of fragrant cut rose cultivar 'Yves Piaget'. Acta Hortic. 1263, 119-124
Rosa, curving petal, growth rate, soluble sugar, osmotic pressure