Rendimiento y calidad de flores de cáñamo (Cannabis sativa l.) según cultivar y fecha de trasplante

Understanding the response of cannabis varieties (Cannabis sativa L.) to different production management practices, both established and under development, may provide practical solutions to current productive and commercial constraints within the sector. In Uruguay, cannabis cultivation faces significant limitations related to production costs, making producers highly dependent on crop performance in each season to ensure continuity of cultivation in subsequent years. The objective of this study was to generate information on the optimal transplanting and/or harvesting periods of two cannabis varieties, Early Trump (Early T) and Jim’s Saparot (Jim’s S), which have contrasting growth cycles and were used as references for widely cultivated varieties in the country. Three transplanting dates were established for both varieties: November 30, 2023; December 20, 2023; and January 10, 2024, in order to evaluate photoperiod response in terms of yield (kg/ha) and commercial quality (A/B flower categories). The experiment was conducted in the department of Canelones, Uruguay, at the Germinare company’s field during the 2023–2024 growing season. A randomized complete block design (RCBD) with split plots was used, with subplots consisting of 16 plants as the experimental unit. Vegetative growth variables potentially related to yield were measured, including plant height, canopy diameter, and photosynthetically active radiation (PAR) interception. At harvest, quality traits such as flower size and compactness were assessed to determine commercial categories A and B. Yield and quality were evaluated after drying, with commercial standards requiring a final moisture content of 14%. Results showed that the longer-cycle variety, Jim’s S, achieved higher commercial yields across all transplanting dates. This response was largely explained by the positive correlation between vegetative growth variables—plant height, canopy diameter, and PAR interception—and the yield of category B flowers. Additionally, the latest transplanting date for both varieties showed a higher proportion of category A flowers relative to category B, accompanied by a lower vegetative biomass. Management of transplanting date and varietal selection can significantly influence labor use for crop maintenance, harvest, and post-harvest handling, thereby reducing production costs and increasing the likelihood of commercialization based on quality.