The role of carbohydrates in storage induced disk floret degreening in chrysanthemum

Dutch-grown cut chrysanthemums are often shipped over long distances resulting in storage times of up to four weeks. One problem occurring after storage is premature degreening of disk florets. We want to understand the physiological background of disk floret degreening in order to allow breeding against sensitivity to degreening. Disk floret degreening occurs in two steps: first, there is loss of green colour resulting in yellowing, and after that, disk florets turn brown. Sucrose feeding after storage prevents disk floret degreening. Pulsing flower stems with potassium chloride with the same osmolarity compared to the sucrose treatment did not have an effect on degreening. Therefore, the effect of sucrose did not seem to be osmotic but related to energy metabolism. Because of this relation with carbohydrate metabolism, we hypothesized that genotypic differences are explained by their carbohydrate content during the postharvest phase. However, the carbohydrate content of a sensitive and insensitive genotype did not explain these genotypic differences. The sensitive genotype showed higher carbohydrate content during the postharvest phase compared to the insensitive genotype. Our results indicate that storage induced disk floret browning is caused by carbohydrate starvation, but genotypic differences are probably explained by a difference in sensitivity to carbohydrate starvation.