predicted effect on transportation table

light alone, wind alone, heat alone

increase effect on transpiration

light alone reasoning

stoma shape: light opens stomata two ways. Directly, photoreceptors detect blue light and the guard cells swell open. Indirectly, light increases photosynthesis, which lowers CO₂ in the leaf air spaces, and the guard cells open in response. Open stomata mean lower stomatal resistance, so more water vapor diffuses out. The LED adds little heat, so relative humidity and the vapor gradient stay about the same

wind alone

Boundary layer: Still air next to the leaf becomes humid and acts as a barrier to diffusion. Wind mixes this layer with the surrounding air, which thins the boundary layer and lowers resistance. Humid air is swept away, so the humidity difference between the leaf and the air stays large. Stomata are unchanged, since wind doesn’t directly change light or CO₂.

heat alone

Relative humidity and vapor gradient: Warm air holds more water. If the air’s actual water content stays the same, its relative humidity drops (the manual’s example: 100% at 20°C becomes about 66% at 30°C). The air inside the leaf stays at 100%, so the difference between inside and outside grows. A steeper diffusion gradient means faster transpiration. Stomata and boundary layer are not the main factors here.

numerator (diffusion gradient)

heat

denominator (stomatal resistance)

light

denominator (boudnary layer resistance)

wind