Effect of different water regimes on physiology, growth and yield of industrial hemp in field conditions

Abstract

Context: Drought and waterlogging limit crop production by disrupting physiological processes, thereby affecting growth and yield. Although hemp’s (Cannabis sativa L.) responses to soil moisture extremes have been partially studied, they remain insufficiently explored under field conditions. Aims: This study aimed to address the knowledge gap by exploring the physiological, growth, and yield responses of industrial hemp under varying water availability from drought to waterlogging, and to develop predictive models for hemp yield on the basis of water supply. Methods: Two field experiments were conducted in south-eastern Tasmania, Australia, over two seasons (2018/2019 and 2019/2020). Varying water supply levels were applied to induce various soil moisture conditions, from deficiency to waterlogging. Data were collected to assess the physiological (leaf gas exchange, transpiration, chlorophyll content), growth, and yield responses (leaf area index, bark and seed yield) of the hemp cultivar ‘Ferimon 12’. Key results: The study found that hemp was highly sensitive to both drought and waterlogging. In 2018/2019, severe drought (W4) reduced photosynthesis by ~50% and growth and yield by over 50% compared with maximum irrigation (W1). In 2019/2020, excess water in W5 and W6 caused waterlogging during vegetative and early flowering, reducing photosynthesis by 20–30% and limiting growth compared with W8. Conclusions: Hemp growth and yield declined under both drought and waterlogging, with partial recovery after improved water conditions, highlighting the need for optimal water supply. Implications: The findings enhance understanding of hemp’s resilience to moisture stress, and support better crop management in regions facing variable rainfall and irrigation challenges.