Enter your plant's Transpiration Rate (E), Leaf Temperature, Air Temperature, Relative Humidity, and Atmospheric Pressure to calculate Stomatal Conductance (Gs), Vapor Pressure Deficit (VPD), and Saturation Vapor Pressure.
Stomatal Conductance (Gs)
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Vapor Pressure Deficit (VPD)
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Saturation Vapor Pressure
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Actual Vapor Pressure
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Stomatal conductance (Gs) measures how easily water vapor and gases can pass through leaf stomata. It's crucial for understanding plant water use efficiency, photosynthesis rates, and responses to environmental stress.
Stomatal conductance is calculated using the formula Gs = E / VPD, where E is the transpiration rate and VPD is the vapor pressure deficit. This relationship is based on Fick's law of diffusion.
Stomatal conductance is commonly expressed in mol m⁻² s⁻¹ (moles per square meter per second) or mmol m⁻² s⁻¹. Some older literature may use cm s⁻¹, but SI units are now standard.
Stomatal conductance is influenced by light intensity, CO₂ concentration, leaf water potential, vapor pressure deficit, temperature, and plant hormones like ABA. Environmental stress typically reduces conductance.
VPD is the difference between saturation vapor pressure and actual vapor pressure, representing the atmosphere's drying power. Higher VPD typically leads to lower stomatal conductance as plants conserve water.
Stomatal conductance typically ranges from 0.01-0.5 mol m⁻² s⁻¹ for most plants under normal conditions. Values vary widely with species, environmental conditions, and plant water status.
Modern gas exchange systems are highly accurate, with typical measurement uncertainties of ±2-5% for transpiration rates. Proper calibration and environmental control are essential for reliable measurements.