Plant growth regulators are broadly classified into two major groups The meristematic cells present at the root and shoot apices divide mitotically and increase the length of the plant body. This is known as primary growth. Secondary growth is referred to as the increase in the diameter of the plant body by the division of the secondary meristem. Plants are autotrophs. They require light for manufacturing their food. Limited light or the absence of it greatly affects the growth of the plant. The intensity of light, quality of light, and light duration influence the movement of stomata, chlorophyll synthesis, photosynthesis, and various other physiological factors. Light also encourages flowering and fruiting. During winters when the days are short, the growth of the plants is retarded