Lebanese Cannabis: Agronomic and Essential Oil Characteristics as Affected by Sowing Date and Irrigation Practice

Abstract

A field experiment was carried out in Lebanon to assess the agronomic and essential oil characteristics of cannabis as affected by sowing date and irrigation practice. The experiment consisted of a split-plot design with the water regime being the main factor (Iopt-irrigated when the readily available soil water is depleted; I50- receiving 50% of the irrigation amounts in Iopt treatments) and sowing date as the sub-plot factor (mid-April; end of April; mid-May). Biometric and seed quality parameters of the cannabis crop were determined. The essential oils (EO) of the inflorescence were subjected to a multivariate analysis such as principal component analysis (PCA) and hierarchical cluster analysis (HCA). The obtained results revealed that the aboveground fresh biomass, the dry matter, and the plant height were 55.08%, 59.62%, and 43.11% higher in Iopt than in I50, respectively. However, the EO content was neither statistically affected by the irrigation regime nor by the sowing date. Under early sowing, both the water-use efficiency (WUE) for biomass and the EO production reached their highest values. All treatments presented a similar seed composition except that the crude fat and crude protein content were more elevated in Iopt than in I50 treatments. The main extracted essential oils in cannabis inflorescence corresponded to twenty-six identified compounds representing 79.34% of the monoterpenes and 81.25% of the sesquiterpenes. The monoterpenes were highly correlated with the irrigation treatment and early-April sowing while the sesquiterpenes were better enhanced under I50 and end of April to mid-May sowing. The study reveals that agronomic practices lead to differential responses of pharmacologically useful plant compounds for improved health benefits. Further research is required to clarify the potential for cannabis cultivation in Lebanon.