Impact of Plant Density and Irrigation on Yield of Hemp (Cannabis sativa L.) in a Mediterranean Semi-arid Environment

Within the context of climate change, water scarcity is the major constraint to the viability of many crops. Thus, it is necessary to develop strategies for sustainable water management, and introduce alternative crops to sustain the viability of agro-ecosystems. The main objective of this work was to assess the performance of hemp (Cannabis sativa L.) subjected to different plant densities and irrigation. Two cultivars (Carma and Ermes) were tested at three plant densities i.e. ۴۰,۰۰۰, ۲۰,۰۰۰, and ۱۰,۰۰۰ plants ha-۱, under two irrigation regimes: i) fully irrigated with total water supply equal to ۱۰۰% of ETc; and ii) deficit irrigation with ۸۰% of ETc. The experimental design was a split-split plot with four replications per combination. At harvest, yield and its components (weight, plant height, stem diameter, and the weight of leaves and flowers relative to the stem weight) were evaluated. Also, the production of chemical compounds for medical use (terpenoids, and fatty acids Omega ۳ and ۶) were analyzed. The results showed that cv. Carma was the most appropriate in agricultural terms, with a yield significantly higher than cv. Ermes. In terms of plant density, ۴۰,۰۰۰ and ۲۰,۰۰۰ plants ha-۱ gave the best results for yield, without significant impact by irrigation rates. Regarding the capability of these varieties to produce relevant chemicals, cv. Ermes yielded higher amounts than did cv. Carma. This work offers a preliminary assessment for hemp cultivation in Andalusia (SW Spain), with important potential under local agro-climatic conditions.