Question

Leaf shape and leaf pubescence affect energy balance due to their effect on (choose any/all that apply) A) radiant heat input B) Metabolic heat loss C) sensible heat exchange D) the leaf boundary layer E) stomatal conductance

Answer 1

Plants may adjust energy balance through leaf reflective properties (Pubescence), orientation and changes in transpirational water loss (Controlled by Stomata), changes in surface roughness as well as due to the presence of boundary layers (Lowering of convective heat loss).

leaf pubescence is known to modify the leaf energy balance and dramatically reduces the photosynthetic rate. The reduction in the photosynthetic rate is caused by decreased light absorption rather than decreased carbon dioxide conductance through the boundary layer. Leaf hair also lowers convective heat loss (hair traps air) and will thus not lose as much as heat. Also, the boundary layer thickness is related to leaf size and surface roughness. Generally, small smooth leaves have thin boundary layers and lose more heat. Boundary layer also decreases with increased leaf serration. More reflection of light due to pubescence reduces the transpirational loss of water, reduced transpiration leads to increased leaf temperature.

thus, the correct option will be:

A) radiant heat input

D) the leaf boundary

E) stomatal conductance.