Volatiles in Different Floral Organs, and Effect of Floral Characteristics on Yield of Extract from Boronia megastigma (Nees)

The relative amounts of volatile compounds in the extract and headspace from each floral organ were assessed in order to identify the main organs for accumulation and emission. The mass of flowers/organs, the number/density of oil glands and yield of volatiles were examined for their relationship with extract yield, in clonal and non-clonal plants. Boronia flowers were divided into component organs and the solvent extractable product and headspace above each organ type was quantified. The petals comprised 50% of the weight of the flowers, and the stigma 20%; however, the stigma contributed 70% of the total volatile compounds to extract from the whole flower. Proportionately more β-ionone and dodecyl acetate were emitted from the stigma and anthers than were contained in the extract, compared with other volatiles. The sexual organs are morphologically equipped for emission of volatiles to attract pollinators. Between non-clonal plants, there was a lower coefficient of variation for extract yield than for values relating to extract composition, indicating that the former is more heritable than the latter. Variation between clonal plants was reduced compared with variation between non-clonal plants. The environment modifies yield and quality of extract in clonal plants, indicating that both have relatively low heritability. No significant relationships between any floral characteristics and extract yield were found. Biosynthetic potential to accumulate extract is therefore of prime importance, and the effect of environment on this potential should be the subject of future work.