Influence of environmental factors on the essential oil variability of Thymbra capitata (L.) Cav. growing wild in South Apulia

The composition of officinal plants in terms of active principles exhibits high intraspecific variability which is determined not only genetically but also by environmental conditions, growth area and harvesting time. This study analyzed the essential oil variability in Thymbra capitata (L.) Cav. in specimens growing wild in 23 places in Southern Puglia (Italy). The results show high chemical polymorphism in the oil content of T. capitata. Application of the spatial autocorrelation index to the principal components highlighted a relationship between thermal parameters and the composition in terms of active principles. The carvacrol chemotype was only present under the hottest and driest conditions. These results show that not only is the biosynthetic pathway of phenolic monoterpenes in T. capitata favored in high-temperature environments, as reported in other Lamiaceae, but also that carvacrol is present only in markedly “Mediterranean-like” environments