Hemp cultivars performance under supplementary lighting using LED and HID lamps in greenhouse cultivation

Hemp (Cannabis sativa L.) is a crop that belongs to the Cannabaceae family, is native to Central Asia, but now cultivated worldwide. Hemp was mainly grown to produce textile fiber. Moreover, the abundance of secondary metabolites, mainly psychotropic alkaloids, and terpenes, has promoted its use as drug since past times. there is a growing interest in this crop, supported by regulatory changes related to hemp-derived products, such as seed oil. The aim of this work was the development of a greenhouse hemp cultivation system during the winter. Plants were grown under supplemental lighting by using HID and LED lamps for two seasons 2020 and 2021 from September-October to February-March. Six hemp cultivars were tested: ‘Carmagnola’, ‘Carmagnola Selezionata’, ‘Felina 32’, ‘Futura 75’, ‘USO 31’, and ‘Santhica 27’ aiming to identify the best performing genotypes. Plant growth rate, chlorophyll, flavonoids content, and chlorophyl a fluorescence were measured. At the end of the growing cycle, the total biomass and seeds yield were measured as well. The results show that plants grown under LED lamps have accumulated significantly higher biomass compared to the plants grown under HID lamps. The results are also supported by the higher seed yield obtained from the LED growing system. Chlorophyll a fluorescence parameters were higher in plants grown under LED light. Finally, the best results in terms of adaptation to greenhouse cultivation were observed for ‘Carmagnola’, ‘Carmagnola Selezionata’, and ‘Felina 32’.