Post-harvest physiology of waratah inflorescences ( Telopea speciosissima, Proteaceae)

Abstract

The post-harvest development and senescence of cut waratah inflorescences ( Telopea speciosissima R.Br.) held at 20° C is described. Individual flowers of the raceme opened and after 4 or more days the perianth abscised, wilted and changed color from bright red to blue-red. The end of vase life was defined as a readily discernible wilting and blueing of either flowers or of the bracts which subtend the inflorescence. During vase life the fresh weight, water content and anthocyanin concentration of both flowers and bracts decreased. Water uptake by the whole inflorescence decreased, the cumulative nett water loss increased and the fresh weight of the inflorescence decreased. Ethylene production by flowers increased to a maximum and then declined, while the low ethylene production by bracts slowly decreased. Vase life was extended from 7.9 to 11.7 days when the vase water was treated with chlorine bactericide (sodium dichloroisocyanurate, 25 mg l −1 available Cl). This increased vase life was accompanied by increased water uptake, decreased nett water loss, and a slower rate of decrease in flower and bract fresh weight and water content. Vase life was also extended by early harvest, when 6% of individual flowers were open rather than 48%. It was concluded that decreased water uptake and flower abscission were the major physiological factors which limited vase life.