The plant factor which affects the rate of transpiration is:
The factors affecting the rate of transpiration can be categorized into two groups - (A) external or environmental factors and (B) internal or structural or plant factors.
External or environmental factors: Atmospheric humidity, temperature, light, wind velocity, soil water content, atmospheric pressure, carbon dioxide concentration.
Internal or structural or plant factors: Leaf area, structural peculiarities of leaf, root shoot ratio, orientation of leaves.