"...To our knowledge, this was the first evaluation of the effects of controlled drought stress on cannabis; although, as previously described, drought can increase essential oil yield in some herbaceous crops. In drought-stressed sage, essential oil and monoterpene yield can increase up to 281% (
Bettaieb et al., 2009) and 20% (
Nowak et al., 2010), respectively, over a well-watered control. Likewise, in curly-leafed parsley (
Petroselinum crispum ssp.
crispum L. cv. curly-leafed) grown under drought stressed conditions, plants were smaller but had higher oil concentrations than the well-watered control. The density of the plants could therefore be increased to accommodate the decreased size and essential oil yield per unit area would be higher (
Petropoulos et al., 2008).
Increases in secondary metabolite concentration due to drought stress usually coincides with reduced growth; however, this was not the case in the present study, at least in terms of inflorescence growth because there was no difference in inflorescence dry weight between drought and control groups. Secondary metabolites are formed from photosynthetic carbon (
Peñuelas and Llusià, 2002), and drought can reduce Pn, as exemplified in the present study. In fact, it is common for Pn of plants exposed to drought stress to recover only to 40% to 60% of their predrought levels on the day after irrigation, and Pn may never fully recover (
Delfine et al., 2005;
Kirschbaum, 1987;
Sofo et al., 2005). Nonetheless, in the present study, the yield of some cannabinoids increased irrespective of reduced carbon assimilation. Protective mechanisms help plants tolerate drought until some cumulative physiological threshold is exceeded, and only at this point is growth impeded (
Ali, 2010;
Xu et al., 2010). A period of drought insufficient to impede growth, such as in the present study, may be crucial to increasing secondary metabolite yield."
An understanding of the biochemical origins of cannabinoids and how they relate to other secondary metabolites may be useful to speculate how drought stress increased cannabinoid yield in the present study. For example, cannabinoids are closely related to some terpenoids that protect plants under stress.
It's interesting to note that oils are enhanced in plants containing them, parallels may be drawn, there are (at least) 2 camps to almost every debate, in the final analysis it all comes down to personal preference based on some kind of analysis or proven science or 'bro' science! For or against, why knock it, after all, your the one ingesting what you grow, you and your bro, and your cussin' cousin flo! lolo
