Cold-storage-induced changes in chlorophyll fluorescence of kangaroo paw Bush Dawn flowers

Abstract

Effects on vase life and chlorophyll fluorescence were evaluated for kangaroo paw Bush Dawn flowers harvested from 3 growth environments and kept at 3 storage temperatures for 4 storage periods. Flowers were grown in a glasshouse, shadehouse and in the open. Harvested flowers were stored at 0, 7.5 or 13°C for 1, 2, 3 or 4 weeks. Minimum fluorescence values decreased progressively from 0.103 to 0.078 as storage temperatures increased from 0 to 13°C. Relative fluorescence ratios of stored kangaroo paw flowers were altered significantly in response to storage temperature, storage duration and growth environment. Relative fluorescence ratios decreased progressively from 0.778 to 0.649 with increasing storage duration from 1 to 4 weeks. Relative fluorescence values were 0.688, 0.784 and 0.711 for 0, 7.5 and 13°C storage temperatures, respectively. Minimum fluorescence did not differ among the growth environments, but relative fluorescence was highest for the shadehouse (0.760) and lowest for the open (0.695). Vase life was also influenced by storage temperature, storage duration and flower source. Main effect vase lives of flowers were 6.6, 7.2 and 3.4 days for 0, 7.5 and 13°C storage temperatures, respectively. Shorter vase life after storage at 0 than at 7.5°C indicates that Bush Dawn is chilling sensitive. Post-storage longevity of flowers from the shadehouse (6.5 days) and glasshouse (6.3 days) was greater than from the open (4.2 days). Relative fluorescence values, which decreased in a linear manner for all storage temperatures as storage duration increased, were significantly correlated with the vase life.