An assessment of the water use of hemp: a scoping review and bibliometric analysis

Recently, there has been a renewed and rapidly growing interest globally in the cultivation of the non-psychoactive variety of Cannabis more commonly referred to as hemp. However, there remains a scarcity of available scientific information on the water use of hemp to optimally guide its large-scale production. To address this knowledge gap, eligible peer-reviewed publications acquired from the Scopus, Web of Science and Google Scholar abstract and citation databases, were analysed using Biblioshiny and VOSviewer to gain further insights on the water use of this crop. A key finding emanating from this scoping review and bibliometric analysis was that the water use of hemp ranged from approximately 220-700 mm throughout the growing season, with daily water use generally ranging between ~ 4.00 mm d^- 1 to ~ 5.00 mm d^- 1. Variations in water use were primarily due to factors such as climatic regime, meteorological conditions, irrigation and agricultural management practices. Furthermore, several studies demonstrated that hemp's deep rooting system and its unique ability to regulate stomatal conductance and photosynthesis enable it to withstand water stress, increasing its resilience to drought. While these findings provide useful insights into the water use of hemp, there exists a need for further research across a broader range of agro-ecological zones, agricultural management practices and genotypes to gain a more comprehensive and objective understanding of the water use requirements associated with hemp cultivation. This may then facilitate legislation, regulatory frameworks and agricultural management practices to be developed and adapted accordingly to not only optimize hemp production but also to safeguard present and future water resources security.