Leaf water potential
nounPronunciation: /liːf ˈwɔːtə pəˈtenʃəl/
The measure of water's free energy in leaf tissues, expressed in megapascals (MPa), determined by osmotic and matric potentials. Leaf water potential indicates water availability to plants and drives stomatal closure responses during stress conditions.
Plain English
A measurement of how much water stress a plant leaf is experiencing, indicating available water for growth and photosynthesis.
Etymology & History
Usage
"Leaf water potential declined from -0.5 to -2.5 MPa as soil water availability decreased, triggering stomatal closure and reduced photosynthesis."
Style guide notes: Always report values in MPa with appropriate precision; specify measurement time and leaf position; distinguish predawn from midday measurements.
Also known as
Contrasted with
Related Terms
Frequently Asked Questions
What does negative leaf water potential indicate?
More negative values indicate greater water stress and reduced water availability; plants typically close stomata around -1.5 to -2.0 MPa.
How is leaf water potential measured?
Using a Scholander pressure chamber that applies pressure to excised leaves until water appears at the cut surface, indicating water potential.
Why Test Candidates on This?
Fundamental measurement in drought stress research and irrigation scheduling; used to validate genotypic differences in water use efficiency.
Required skill level: Mid