Production of volatiles in brown boronia flowers after harvest. I: Effect of clonal type and incubation temperature

The potential for enhanced concentrations of essential oils (solvent-extracted floral products) in flowers from four genetically distinct clones of brown boronia (Boronia megastigma Nees) as a result of post-harvest incubation was assessed. Flowers were sampled throughout 48 h of incubation at 12 and 30°C. There was significant variation in the changes observed between clones. Increases in the concentration of floral extract as a result of incubation varied from 3% to 19%, the maximum concentration of floral extract observed was 2.13% (dry-weight basis). The volatile portion of the extract increased by between 25 and 117%, and the concentration of β-ionone, the main volatile of interest, increased by between 45 and 181%. The maximum concentration of total volatiles observed was 0.47%, and of β-ionone, 0.165%; all values being expressed as a percentage of dry flower weight. The most significant increase in floral extract, total volatiles and β-ionone after harvest, occurred in clone 250. Increases in all components were greater as a result of incubation at 12°C for 48 h compared with 30°C for 12 h.