POSTHARVEST FLORAL ORGAN FALL IN GERALDTON WAXFLOWER (CHAMELAUCIUM-UNCINATUM SCHAUER)

Possible reasons for, and prevention of, postharvest floral organ fall in Geraldton waxflower (Chamelaucium uncinatum Schauer) were studied. An 11-kg compression load, equivalent to the lidding of a carton, cau sed flower fall amounting to 1 % of the fresh mass of 420-g bunches. F ungal development also resulted in flower abscission. Healthy flowers produced little ethylene (e.g. 0.05 muL/kg.h), while infected flowers produced much more (e.g. 7.71 muL/kg.h) and were shed. Treatment with fungicide (iprodione + mancozeb) and antiethylene compounds [e.g. silv er thiosulfate (STS) pulse, Purafil sorbant] reduced flowerfall in pac kaged flowers. Cut sprigs which suffered severe water deficit also she d flowers. In cv. Elegance, drying to -3.61 MPa elevated ethylene prod uction (e.g. 1.35 muL/kg.h). Flowerfall induced by water deficit could be reduced by pretreatment with a STS pulse (0.5 mmol Ag+/L for 15-22 h at 0-degrees-C or 4 mmol Ag+/L for 20-30 min at about 20-degrees-C) . Pretreatment with a naphthaleneacetic acid dip (50 mg/L for 1 min at room temperature) shortened the vase life of Elegance.