Three Types of Cannabis Sativa L. are Affected by LED Light in Terms of Their Cannabinoid Content, Physiological Characteristics, and Plant Architecture

Abstract

Development and the biosynthesis and storage of secondary metabolites are affected by changes in the light spectrum. This study sought to ascertain how two light sources affected the physiological and yield characteristics of three C. sativa cultivars grown in greenhouses. During the vegetative period, two light sources—LED1 (100 percent white) and LED2 (90 percent red, 8% blue, and less than 1 percent far red)—were applied to the non-psychoactive varieties of Calotoweed, Higthcol, and Souce Cauca. Plant height (4%–26.7%), leaf area (21%–55%), and shoot dry mass (1.9%–30.3%) all decreased under LED2, although biomass was distributed more toward the inflorescences (40.1%–51.6%). The type of light has no discernible impact on the relative amount of chlorophyll. Comparing all three types cultivated under LED2 to plants grown under LED1, decreases were noted in stomatal conductance (4.7%–27.4%), PSII quantum efficiency (1%–11.7%), and electron transport rate (9.2%–15.8%). The dry flower output of the various light kinds and cultivars did not differ much. In comparison to LED2, greater CBD levels (11.9%–13.4%) and CBD per gram of inflorescence (12.9–13.8 g/inflorescence) were noted under LED1. THC concentrations were greater in the Calotoweed (0.5%) and Soucecauca (0.6%) types grown under LED2 than in the plants grown under LED1. These findings show that LED2 altered the canopy architecture, producing more compact plants with higher biomass accumulation in the inflorescence. Nevertheless, these plants showed limitations in photosynthetic capacity, which led to a decrease in CBD synthesis and an increase in THC production. In summary, the type of light altered the architecture of the plant and had an impact on photosynthetic performance as well as the production of THC and CBD.