Essential oils of Rosmarinus officinalis L., effect of harvesting dates, growing media and fertilizers

The effects of the harvesting date, growing media and fertilizers on the yield and chemical composition of the essential oils of Rosmarinus officinalis L. maintained in pots were evaluated. The highest oil yield was always obtained in June, being superior or equal to 1 %. Myrcene was the major component present in the essential oils with concentrations always exceeding 20 %, independent on the factors studied. 1,8-Cineole (8.0-12.2 %), a-pinene (8.8-16.5 %) and, in some instances, camphor (4.4-14.1 %) could be also detected in considerable amounts, however never exceeding the myrcene percentages. The amounts of camphor (4.4-8.5 %) were always inferior to the 1,8-cineole levels (8.8-11.8 %) in the local sandy soil regardless the fertilization used. Generally, the lowest levels of myrcene and verbenone were observed during January and April while the highest amounts of 1,8-cineole was observed in April or June. The yield and the chemical composition of the rosemary oils seemed to be more sensitive to the temperature, photoperiod and collection period than to the growing media material or to the fertilization used