How Does the Color of Roses Affect Evaporation?

Pigments in Roses

• Roses, like all flowers, contain only a few primary pigments. Red, orange, pink, purple and blue roses are colored primarily by anthocyanin. Anthocyanin absorbs light waves in the blue-green section of the light spectrum. Yellow roses, on the other hand, are the result of carotenoids. These pigments absorb the shorter wavelengths located in the blue end of the light spectrum.

Solar Radiation

• Solar radiation is expressed as waves. No matter if the wave is visible, like blue or green light, or invisible, like infrared waves, that wave is carrying energy. Energy translates into heat when it is absorbed by a solid object. Longer waves move slower and heat surfaces less effectively. However, the shorter wavelengths that are absorbed by rose pigments have enough energy to heat the surfaces of the petals -- albeit slightly.

Surface Evaporation

• While surface evaporation is driven by energy, it cannot happen in a void. The environment has to be able to absorb the excess gaseous water being created. Evaporation is increased when the humidity is low and the temperature is high. Wind also plays an important factor, as it carries away those airborne water particles. Roses in locations with adequate circulation and high light will have higher evaporation rates than those stuck in stagnant corners.

Transpiration

• Another type of evaporation that happens across all exposed plant surfaces is called transpiration. Stomas, small openings in plant tissues, allow the transfer of water from the inside of the plant to the environment. While stomas are stimulated by the blue light of dawn, plant pigments do not have a direct effect on transpiration.