Ryozo Sakiyama

Effects of temperature and stem length on changes in carbohydrate content in summer-grown cut chrysanthemums during development and senescence

Abstract Changes in the carbohydrate content in capitula, stems, and leaves were investigated in cut chrysanthemum Dendranthema×grandiflorum (Ramat.) Kitamura ‘Seiun’ plants with 60-cm stems held at 20, 25 and 30°C for 27 days postharvest. In addition, plants with 20-cm stems were studied at 25°C. Diameter of the capitula, the angle of the florets, fresh weight (FW) and dry weight (DW) increased more slowly at 30°C/60 cm and 25°C/20 cm than at 20°C/60 cm and 25°C/60 cm. The number of well-developed florets was notably smaller, and the number of tubular-shaped florets was larger at 30°C/60 cm than at 20°C/60 cm. Glucose and fructose concentrations in the capitula increased, although they decreased midway through treatment at 30°C/60 cm. Fructose concentrations in the stems, and in particular in the middle stems, were greater at 30°C/60 cm than at 20°C/60 cm and 25°C/60 cm. The increase in the total DW during treatments suggested that photosynthesis was occurring in the leaves and that photosynthates were a main source for the capitula and stems. Development of the capitula was suppressed, which was related to the reduction in its carbohydrate supply. Wilting of petals was not accelerated at high temperatures and with short-stem treatments.