Physiological and morphological responses of industrial hemp (Cannabis sativa L.) to water deficit

With drought projected to increase in severity and frequency in the future, selection of emerging drought-tolerant species that exhibit improved water use efficiency will be key to maintaining cropping productivity. Industrial hemp (Cannabis sativa) shows potential for cropping in water-limited environments, but studies into its water use and drought tolerance are conflicting. We evaluated the morphological, physiological and biochemical responses of the industrial hemp cultivar ‘Black Label’ to extreme and moderate water deficit in an 85-day greenhouse experiment. Under water deficit, hemp reduced biomass production and total seed yield, but maintained filled seeds for effective reproduction. Water use efficiency, measured using δ¹³C isotope analysis, increased under water deficit due to reductions in stomatal opening and transpiration. Water deficit increased proline accumulation, likely to allow osmotic adjustment. While extreme water deficit initiated water stress responses in hemp, plants were able to survive and maintain seed production. We report that hemp can survive at exceptionally low levels of soil water availability, which could have far-reaching consequences as agricultural industries pursue innovative, sustainable and water-efficient crops for the future.