Regulation of secondary metabolism in Cannabis sativa L. by abscisic acid and water deficit during early flower development and after recovery

• Early flowering drought decreases cannabinoid but increases sesquiterpene content. • Cannabigerolic acid and monoterpene content increases in post-drought recovery. • Cannabis secondary metabolic drought response is developmentally dependent. • Terpene metabolism regulation independent of ABA in drought response. Female cannabis ( Cannabis sativa L.) flowers produce medicinally important secondary metabolites in the form of cannabinoids and terpenes. Cannabis has been demonstrated to be moderately drought tolerant; it can recover from short-term drought experienced in late flowering without lasting negative impact and this treatment can increase content of cannabinoids. In this study, we tested short-term drought stress (i.e. water deficit (WD)) and abscisic acid (ABA) treatments during early flowering followed by a prolonged recovery period until harvest time (floral maturity). Floral content of cannabinoids and terpenes were quantified during treatment and at post-recovery harvest. Plant morphology was measured at harvest. Results showed that cannabinoids decreased while sesquiterpenes increased during early flowering WD, whereas ABA treatment only caused cannabinoids to decrease. At harvest, cannabinoids were no longer negatively affected in recovered WD and ABA treated plants, with cannabigerolic acid (CBGA) higher in both treatments than in controls. Monoterpenes increased in content in the WD plants at harvest. These results showed that cannabis secondary metabolic drought response is developmentally dependent because the findings differed from those observed in the same experimental system during late-flowering drought treatments. By comparing drought and ABA treatments we observed that terpene metabolism during drought is controlled by ABA-independent regulation pathway. Finally, results from post-drought recovery confirmed the drought resilience of cannabis as there was no loss in biomass, while secondary metabolic content was elevated.