This is just an educated guess. As the purple pigment, caused by anthocyanins, are on the bottom side of the plant, their purpose could probably be to direct the light.
Specifically, a purple pigment on the bottom of the plant would absorb certain wavelengths near the purple spectrum, and reflect other wavelengths back toward the portion of the plant with chlorophyll. In this way, light does not simply pass through the leaf, instead it is reflected back in towards the chlorophyll to maximize the amount of light being used for photosynthesis.
Bladder sphincter is what I've always know it to be.
After plants absorb energy from the Sun, the energy gets converted into chemical energy for the plant to carry out life activities. Chemical energy is used up by the different processes within the plant cells (e.g. cellular respiration, photosynthesis).
Please correct me if I'm wrong.. :)
From an agronomical point of view, there is a lot that the grower can do to maximize sugarcane yield. Proper crop nutrition is an important factor to achieve this.
In a large number of cases, nutrients that drive sugarcane yield forward, will also improve the sugar content and quality of the harvested sugarcane crop.
Most required nutrients have specific roles to play in improving yield: