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 production were measured for Geraldton waxflower (Chamelaucium uncinatum) flowers in order to characterise flower development and senescence in this cut flower crop. Ten sequential stages of floral development were identified. Sugar levels increased during bud development, the highest concentrations (c. 130 mg sucrose equivalents/g dry weight (DW) being measured during the nectiferous stages of flower opening. There was little variation in either soluble or insoluble protein levels during flower development, levels averaging around 19 and 25 mg bovine serum albumin (BSA) equivalents/g DW, respectively. In flowers cut and maintained individually, sugar and protein levels decreased rapidly after harvest, 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 increased slightly (Day 4) before decreasing with senescence (Day 8). Flowers on sprigs appeared to deteriorate at c. 8 days after harvest, in concert with the decreasing sugar and protein levels. Respiration rates were initially high (1432 ml/kg per h) for the flowers from harvested sprigs, 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 absence of respiratory and ethylene production peaks indicates that Geraldton waxflower flowers are nonclimacteric in nature