EFFECT OF LIGHT QUALITY ON GROWTH AND ESSENTIAL OIL COMPOSITION IN ROSEMARY

Red and far-red light that influence plant morphology and phenology may play an important role in modulate essential oil production of rosemary (Rosmarinus officinalis L.). In a study on the growth, development, and essential oil production of rosemary growing in a glasshouse, the addition of end-of-day light treatment with red (660 nm) and far-red (730 nm) light had significant effects on the content and constituents of essential oil as compared with control plants not exposed to light treatments. Potted rosemary seedlings (10 – 13 cm tall) exposed to red or far-red light for 3 h beginning 15 min before sunset for 28 days varied in levels of limonene, bornyl acetate, α-cedrene, neril acetate, α-pinene, camphene, p-cymene, α-terpinolene, and geranyl acetate production as compared with controls. Far-red light promoted and red light inhibited the synthesis of -pinene, camphene, and p-cymene. Red light promoted the synthesis of limonene and bornyl acetate, -cedrene, and neryl acetate. Far-red light increased and red light decreased oil production as compared with non-lighted control. Both red and far-red light treatments induced plant growth variations with both red and far-red treated seedlings exposed to end-of-day light were taller than controls. The far-red light treatment significantly increased internode length as compared with the control.