How would a reduced level of chlorphyll in a plant cause a stunted growth? Can anything else affect growth?

Chlorophyll is vital for photosynthesis, which is how the plant makes glucose for energy. If there is less photosynthesis, there will be less glucose made and so less energy released for growth. Glucose is needed for making amino acids, proteins and cellulose for growth. The word equation for photosynthesis is carbon dioxide + water (in the presence of light energy and chlorophyll) ---> glucose + oxygen. Therefore, the amount of light energy a plant is able to receive will also affect the rate of photosynthesis. Chlorophyll absorbs blue and red light most strongly, but is a poorly absorbs green light. A lack of water would also decrease the rate of photosynthesis, as would a lack of carbon dioxide, however it's unlikely this would ever be a problem.