CHANGES IN SUGAR, PROTEIN, RESPIRATION, AND ETHYLENE IN DEVELOPING AND HARVESTED GERALDTON WAXFLOWER (CHAMELAUCIUM-UNCINATUM) FLOWERS

Sugar and protein levels and rates of respiration and ethylene product ion were measured for Geraldton waxflower (Chamelaucium uncinatum) flo wers in order to characterise flower development and senescence in thi s cut flower crop. Ten sequential stages of floral development were id entified. Sugar levels increased during bud development, the highest c oncentrations (c. 130 mg sucrose equivalents/g dry weight (DW) being m easured during the nectiferous stages of flower opening. There was lit tle variation in either soluble or insoluble protein levels during flo wer development, levels averaging around 19 and 25 mg bovine serum alb umin (BSA) equivalents/g DW, respectively. In flowers cut and maintain ed individually, sugar and protein levels decreased rapidly after harv est, suggesting their use as respiratory substrates. Sprig senescence was characterised by loss in fresh weight and decreasing water use. In flowers taken from sprigs in vases, sugar and protein levels increase d slightly (Day 4) before decreasing with senescence (Day 8). Flowers on sprigs appeared to deteriorate at c. 8 days after harvest, in conce rt with the decreasing sugar and protein levels. Respiration rates wer e initially high (1432 ml/kg per h) for the flowers from harvested spr igs, and declined during vase life. Ethylene production also decreased during vase life from an initial level of 1.32 mu l/kg per h. The abs ence of respiratory and ethylene production peaks indicates that Geral dton waxflower flowers are nonclimacteric in nature.