Variation in the essential oil composition of Cannabis sativa L. var. 'Fedora 17' from two Tuscan sites

Cannabis sativa L. ‘Fedora 17’ is a French monoecious cultivar commonly used for fiber and seed production (with less than 0.2% w/w of Δ9-THC, Regulation EC No. 1124/2008). The aim of this study was to assess the effect of the cultivation site (lowland and upland) on the EO yield and composition. The characteristics of the EO from the spring-sown crop was compared with that obtained from the volunteer hemp plants grown in the next year. Plant samples (flowering cymes) from two sites (Santa Luce and Cascina, respectively at 220 and 10 m above sea level) of Pisa (Italy) province have been harvested at the beginning of the flowering time (August 2015) from spring-sown crops. Volunteer plants grown from seeds that were dropped into the soil were also sampled from the Cascina site in November 2016. All the samples were hydrodistilled: the highest yields were obtained from Cascina and Santa Luce August samples (0.06 and 0.12% respectively), while the lowest was found in Cascina November sample (0.01%). Overall, 99 volatile organic compounds (VOCs) were identified: monoterpene and sesquiterpene hydrocarbons represent over 60% of all the EOs, and β-caryophyllene is the most abundant VOC in all the compositions. The EO composition of the plants from Cascina and Santa Luce sampled in 2015 was similar. The volunteer samples showed the major differences in the EO composition compared to the spring-sown crop grown in the same site the year before: α-pinene decrements of over 60% compared to the 2015 samples; α- and β-selinenes were not detected, while their relative abundance was ca. 3% in the 2015 EOs. Valencene and viridiflorene, instead, which were not detected in the 2015 compositions, showed relevant abundances in the 2016 sample. Moreover, myrcene, (E)-β-ocimene, and terpinolene incremented in the volunteer sample EO. These results were analyzed by means of multivariate statistical analyses. The Hierarchical Cluster Analysis (HCA) gathers EOs in area-driven groups, except for the volunteer sample, which constitutes a group by itself. The Principal Component Analysis (PCA) plot groups samples based on the gathering period of the inflorescence, plotting the November 2016 Cascina EO by itself. Chemometric analysis, though, confirms the peculiarities shown in the composition of the volunteer sample EO. The volunteer spontaneous growth of the same variety of C. sativa seems to matter more, in terms of differences in the EO composition, than the cultivation site. On the other hand, the extraction yield varies based on the site of origin of the sample, as it is higher for Santa Luce specimens.