Plant material and horticultural practice: The experiments were conducted at the Universidade Federal de Lavras between November 2005 and January 2006. Seeds of O. selloi were sown in commercial substrate [Plantmax (Eucatex, Sao Paulo, SP, Brazil)] contained in 72-cell plastic trays and maintained in the greenhouse under intermittent nebulization for 60 days. Seedlings were transplanted to 10 L pots containing a substrate consisting of soil, matured cattle manure and sand (5:3:2), and cultivated under three different light regimes, namely, full sunlight, and sunlight with blue or red shading. Each treatment was repeated seven times and two plants were employed per repetition.

The compositions of the oils varied according to the quality of light. Although the qualitative profiles of the oils of plants grown under full sunlight or red shading were similar, that obtained from plants grown under blue shading presented a larger number of constituents. The highest level of methyl chavicol (93.2%), the major component of the oil, was observed in plants grown under full sunlight.