Impact of varying water stress periods (water shortage vs. waterlogging) on Cannabis sativa growth, leaf physiology, and CBD content

It is important to understand how water stress treatments (water shortage and waterlogging) affect plant physiology and cannabinoid levels in cannabis plants. This study evaluated the effects of different periods (7, 14, and 21 days) of water stress (water shortage vs. waterlogging) on growth, leaf physiology, and cannabinoid accumulation in Cannabis sativa plants at vegetative and reproductive stages. The first experiment evaluated the effects of 7 days of water stress treatments during the vegetative stage. The second study examined the physiological responses to different durations (7, 14, and 21 days) of water stress treatments during the reproductive phase. Waterlogging for seven days during the vegetative stage had a more negative impact on growth parameters, especially root length (17.2 cm), compared to water shortage (31.6 cm) and control plants (17.2 cm). During the reproductive stage, water shortage for 21 days significantly reduced stomatal conductance (gs) (34.9 µmol·m-2·s-1), leaf area index (LAI) (1.01), total plant dry weight (TPDW) (52 g), and photosynthetic efficiency (Phi2:0.2) compared to waterlogging (gs: 113 µmol·m-2·s-1; LAI: 2.39; TPDW: 62 g; Phi:0.3), and control plants (gs: 226 µmol·m-2·s-1; LAI: 3.82; TPDW: 80 g; Phi:0.65). Both water stress conditions decreased cannabinoid content when the stress period was prolonged during the reproductive stage (Total CBD: 45 and 41 mg·g-1 for water shortage and waterlogging, respectively) compared with control plants (Total CBD: 105 mg·g-1). This study found that water stress conditions, both waterlogging and water shortage, influenced cannabinoid biosynthesis during the reproductive stage.