Water availability plays a critical role in the growth and chemical makeup of marijuana plants, according to a new study published in the journal Plants.
Researchers from the University of Padua examined how water stress during different growth stages impacts plant development, cannabinoid content, and terpene composition in two cannabidiol (CBD)-dominant varieties of Cannabis sativa.
Plants subjected to moderate and severe water stress showed notable changes in biomass distribution, with dry biomass increasing but harvest index decreasing, especially when stress occurred during the flowering stage. The researchers found that CBD levels dropped as water stress intensified, while tetrahydrocannabinol (THC) levels rose under stress applied during the vegetative stage. Levels of cannabinol (CBN), a degradation product of THC, also increased, suggesting that stress conditions accelerated THC breakdown.
While terpene composition was primarily determined by the plant’s genetic background, water stress slightly altered some minor volatile compounds. However, the dominant terpenes that define each variety’s aroma profile remained largely unaffected.
The findings highlight the importance of carefully managing irrigation, as both the timing and severity of water stress can significantly influence cannabinoid production and overall plant performance, especially for high-value medicinal and aromatic marijuana crops.
