S25 - Session O4 - Light supplementation on Cannabis sativa greenhouses: what is the reality?

Authors: Verónica Codesido Sampedro *, Laura Agui, José Luis Valencia Castellano, Julio Sánchez Ramírez, Antonio Sancho

Cannabis sativa L. is one of the most valuable crops in nature. It could be used to produce fibre, foods, textiles, construction materials and medicines. Due to its prohibition history, most of the crops were historically grown into indoor facilities. Thanks to new regulations on many countries and the increasing interest of the crop, many companies started their operations into greenhouses. To achieve from 3 to 5 cycles per year, light supplementation seems essential to obtain higher yields, meanly on vegetative phase of winter periods. In this study, four different light solutions, differing on intensity and spectrum from four different companies were compared with natural light supplementation on two varieties of high Δ9-THC growing into a 640 m 2 high-tech greenhouse. Weekly height of all the plants, chlorophyll content and PAR after vegetative period II and generative period II, accumulation of mainly cannabinoids during the flowering process, biomass and fresh weight at harvest moment, and flowers dry weight, percentage of flowers biomass, cannabinoids and terpenes content after drying were measured. Surprisingly, there were significant differences between light solutions for all the measured traits, indicating that a mix model of light supplementation must be applied to obtain the best results when harvesting the cannabis crop.