Crop steering through osmotic stress can reduce height but reduced yield in medical Cannabis

Precision water stress, achieved via osmotic stress, has the potential to control plant size and improve crop quality without reducing yield, but results across species and cultivars have been inconsistent.

This study examined the effects of elevated salinity on two diverse Cannabis sativa cultivars, Trump and Cherry. One group (control group) was grown at 4 mS cm⁻¹ (-0.14 MPa), one group at 8 mS cm⁻¹ (-0.28 MPa), and a third (hybrid) group at 8 mS cm⁻¹ (to reduce vegetative growth) until flowering and then reduced to 4 mS cm⁻¹ to minimize effect on flower yield.

Plant height was reduced 15% in both the high and hybrid treatments. Flower yield decreased by 20% in cv. 'Trump' in the hybrid treatment, but the decrease in yield in the high salinity treatment was not statistically significant. In cv. 'Cherry', flower yield declined by approximately 20% in both the constant high salinity and hybrid treatments. There was no difference in cannabinoid concentrations among treatments in either cultivar.

These findings indicate that Cannabis sativa is highly tolerant to osmotic stress, but the response varies by cultivar. It is difficult to reduce plant size without reducing yield. There is no evidence that increased salinity altered cannabinoid concentration.