Essential Oil Responses to Water Stress in Greek Oregano Populations

Origanum vulgare subsp. hirtum, known as Greek oregano, has an excellent quality and good adaptability to scarcity of water, growing in several habitats of Greece and its genetic variability could be used for the production of new products. The current study aims to investigate the response of Greek oregano genotypes, originated from different mountain districts, under different water availability. The results showed that the genotypes were differentiated for dry matter production for both years. The populations Pelion and Kissavos showed superiority over the population Olympus by 27.2% and 18.5% respectively, for the years of experimentation. The highest essential oil yield was recorded in Kissavos population which showed 12.8% and 14.5% superiority over the two other populations for 2011 and 2012, respectively. The results showed the impact of water availability to the produced dry matter and essential oil yield and the interaction with the genotypes. The population Olympus, accumulated the highest dry matter at the irrigation level 60%, while for the populations Pelion and Kissavos the highest value was recorded at irrigation level 80%. The additional irrigation level didn't contribute to a further production of dry matter. In conclusion, genotype and water supply can affect the dry matter, the essential oil content and yield of oregano. Oregano plants required an optimum level of irrigation to maximize the economic results, depending on the population used in this study.