4.4. Isolation of Oils

Kunzea oil was obtained by steam distillation of leaves and twigs from wild K. ambigua. Each sample from each of the blocks at each seasonal time point was divided into 2 × 200 g duplicates and the essential oils were obtained by steam distillation for five hours using a Clevenger-type apparatus. Essential oils were weighed and calculated as grams of oil per gram of dry plant material (oil content: g/g DW). The oils were stored at 4 °C prior to gas chromatography (GC) analyses. Essential oil yield (g DW/m²) was calculated using the formula:

Cumulative essential oil yield (g DW/m²) at each sampling date was calculated by adding the essential oil yield (g DW/m²) recorded at the beginning of the trial (28 December 2018) to that obtained from harvest at any given date. The major components of kunzea essential oil were α-pinene, 1,8-cineole, terpinen-4-ol, bicyclogermacrene, globulol, viridiflorol and ledol, as analysed by GC/FID (Section 4.5. Gas Chromatography) and are presented as a percentage of the total oil yield. All other chemical constituents were grouped, and their percentages were summed and reported as minor components.