The main role of blue light in plant growth is to drive photosynthesis and regulate various physiological processes. Blue light is essential for the production of chlorophyll, enhancing the plant's ability to absorb light energy for converting carbon dioxide and water into glucose and oxygen using sunlight. It also influences phototropism, promoting growth towards light, and plays a role in regulating stomatal opening for gas exchange. Adequate blue light exposure contributes to healthier, more efficient plant growth and development.