Effect of light intensity and branch origin position on Cannabis sativa inflorescence density and THC content

ISHS Secretariat
Effect of light intensity and branch origin position on Cannabis sativa inflorescence density and THC content

Sebastian Dam is a former undergraduate student of Dr. Youbin Zheng (University of Guelph) and is currently a crop consultant at Cultivation Coaches in Canada. Sebastian’s research consists of optimizing cannabis cultivation techniques. Throughout the world, as the cultivation of cannabis is becoming legal for both medicinal and recreational use, documented research for this new crop is in high demand. The important quality metrics for production are consistent inflorescence density and tetrahydrocannabinol (THC) content throughout the plant and between cultivation cycles. To achieve a homozygous plant, understanding the factors influencing THC content and bud density are crucial. This study aimed to unravel the potential impact of branch origin on cannabis inflorescence characteristics. To isolate the branch origin as a variable, environmental parameters were controlled, and light intensity was measured and isolated as a result. The treatment plants were trained to receive equal amounts of light through a technique called ‘topping’ and physical manipulation of the branches. Untreated plants were grown naturally resulting in differential light intensities. Branch origin was found to have no impact on the inflorescence density or THC content. However, inflorescence density was shown to be significantly impacted by light intensity. Trained plants exhibited uniform density between top and bottom inflorescences, whereas untrained plants displayed lower density in the bottom inflorescences. While light intensity did impact inflorescence density, THC content analysis revealed no significant differences between top and bottom inflorescences in both trained and untrained plants. Through these findings and the emerging body of research on this topic, it is expected that the THC content will not be affected by light intensity above a certain minimum threshold. The study supports Dr. Zheng’s hypothesis that the potential minimum threshold for light intensity to impact THC content is around 200 µmol m-² s-¹ but further research is necessary to confirm this.

Sebastian Dam won the ISHS Young Minds Award for the best oral presentation at the GreenSys2023: International Symposium on New Technologies for Sustainable Greenhouse Systems in Mexico in October 2023.

Sebastian Dam, 19105 Blue Water Avenue, Tilbury Ontario N0P2L0, Canada, e-mail: sebastian_dam1@hotmail.com

The article is available in Chronica Horticulturae

cannabis sativa
Young Minds Award Winners