The 1st Chakra is known as the Root or Base Chakra which exhibits the qualities of physical energy and vitality.
The color Red is the color of physical energy, passion, courage, power, will, and desire. 
Red is powerfully linked to our most primitive physical and emotional needs of survival and self preservation.
Physically Effects
the adrenal glands, kidneys, spinal column, back, hips, legs and feet. If your immune system is slow-moving, red will give it a kick-start. Red increases fertility in both men and women. Not surprisingly, red helps menstrual problems, blood and the circulation, stop bleeding, heals rashes and wounds.