Cannabis photosynthetic and stomatal responses to water deficit, genotype-dependent drought response, biomass partitioning, and physiological interpretation under measured conditions.
Abiotic disorders
Drought & Root-Zone Water Deficit
Water deficit occurs when root water supply cannot keep pace with plant demand. The useful diagnostic question is not simply whether leaves are drooping, but whether the root zone is actually too dry or unable to deliver water fast enough.
What to look for
- Loss of leaf or petiole turgor associated with a dry root zone
- Rapid container weight loss or uneven dry pockets
- Marginal scorch or slowed expansion after repeated severe dryback
- Symptoms that intensify during peak light, heat, or atmospheric demand
Important look-alikes
- Root-zone hypoxia
- Root disease
- High EC and osmotic stress
- Localized stem or vascular injury
How to confirm
- Measure substrate moisture at more than one depth or location
- Compare irrigation volume and emitter output among affected and unaffected plants
- Inspect roots for physical damage or disease that could limit water delivery
- Review leaf temperature and atmospheric demand during symptom peaks
Management principles
- Restore water supply without converting a dry-root problem into chronic saturation
- Correct blocked emitters or uneven irrigation before changing nutrition
- Reduce extreme environmental demand when roots temporarily cannot keep pace
- Judge recovery by posture and new growth rather than damaged leaf margins
Prevention
- Track dryback trends
- Verify irrigation distribution routinely
- Match container volume and media water-holding characteristics to plant size
- Use environmental records to anticipate periods of unusually high water demand
Visual study guide
- Dry root-zone profile
- Container moisture gradient
- Demand-versus-supply diagram
- Dry-wilt versus wet-wilt comparison
Evidence & further reading
Sources connected to this lesson
These references support specific biological, diagnostic, environmental, or process concepts used in this lesson. They are not a substitute for crop-specific testing or local regulatory guidance.Plant injury from insufficient or excessive root-zone moisture, irrigation diagnosis, overwatering, poor drainage, aeration deficit, and the need to distinguish wet-root and dry-root stress.