Effect of different light‐emitting diodes on vegetative cannabis growth and antioxidant activity
Zohreh Poudineh, Philip Wiredu Addo, Vincent Desaulniers Brousseau, Anne‐Sophie Rufyikiri, Sarah MacPherson, Valérie Orsat, Mark LefsrudAbstract
Background
Cannabis stands as one of the world's oldest plant sources for food and textile fiber. The study aimed to assess the impact of white LED (blue; 446 nm + amber; 595 nm + red; 653 nm), wide PC amber (595 nm), narrow amber (595 nm) + royal blue (430 nm) (NA + RB), and narrow amber (595 nm) + royal blue (430 nm) + cyan blue (485 nm) (NA + RB + CB) on cannabis growth and antioxidant activity during the vegetative stage. Two different propagation methods (seedlings and cuttings) were used.
Results
Significant differences ( p < 0.05) were observed between the LED treatments, with wide amber yielding the highest SPAD values (61.3–64.7), fresh mass (13.4–14.4 g), dry mass (3.2–3.9 g), plant height (20.1–22.5 cm), and stem diameter (4.3–4.4 mm). White LEDs exhibited the least favorable outcomes for all growth parameters. Adding cyan blue to narrow amber (595 nm) + royal blue (430 nm) significantly ( p < 0.05) reduced fresh mass by 14.9–16.4%, plant height in cuttings (11.7–8.8 cm), and stem diameter in seedlings (4–3.8 mm). The addition of cyan blue (485 nm) to the (NA + RB) light significantly ( p < 0.05) produced the highest antioxidant activity in both FRAP value (M) dry matter (g −1 ) (3.8–4) and TEAC (M) dry matter (g −1 ) (88.2–88.6) among all treatments, with wide amber showing the lowest levels.
Conclusion
This research offers promising guidance for cannabis growers to select spectral designs for specific cannabis development stages and production goals, favoring amber‐rich light when vigorous vegetative growth is the priority and blue‐enriched spectra when antioxidant yield is of greater value, including for downstream use of cannabis leaves as a source of antioxidant compounds.