Evaluation changing of essential oil of laurel (Laurus nobilis L.) under water deficit stress conditions

• Relative Growth Rate (RGR), Leaf Mass Area (LMA) and chlorophyll content for both Laurel ecotypes decreased clearly under water stress.
• Water stress induced an increase in essential oil% but at the same time it reduced essential oil yield.
• Eight six components were determined in essential oils. They characterized by a clear predominance mainly of oxygenated monoterpenes. 1,8-cineol was the main component in two ecotypes.
• In ecotype ‘Annaba’, 1,8 cineol increased with permanent stress (S1 and S2) and diminished by 50% under cyclic severe stress (S22) but in ecotype ‘Bardo’, 1,8 cineol increased with water stress.

The effects of water deficit stress on growth and essential oil yield and composition of Laurel ecotypes (Annaba and Bardo) were studied. The factors studied included two stress intensities of permanent stress: 60% (S1) and 20% (S2) of field capacity or to cyclic water stress, plants being re-watered when the soil moisture dropped to 60% (S11) or 20% (S22) of field capacity. The results of this experiment showed that Relative Growth Rate (RGR), Leaf Mass Area (LMA) and chlorophyll content decreased under water stress especially under severe stress S2. For both ecotypes, essential oil yield was reduced under water deficit stress but essential oil% increased under this condition. Eight six components were determined in essential oils, which were mostly oxygenated monoterpenes. The main components were found to be 1,8-cineol in two ecotypes. In Annaba, 1,8 cineol increased with permanent stress (S1 and S2) and diminished by 50% under cyclic severe stress (S22) but in Bardo, we note that 1,8 cineol increased with water stress, this increase was much higher under cyclic stress (S11 and S22). Water stress decreased the constituents of α-terpinyl acetate, Sabinene and linalool for Annaba. For Bardo, α-terpinyl acetate increased under water stress.