How does light affect plant growth?

Light is the energy source for plants to carry out photosynthesis. What are the effects of light on plants at different stages of plant growth?

Growth direction
The survival of plants depends entirely on the light source. For all outdoor plants, the sun is the only source of light. When the first leaf appears on the plant, it will try to grow towards the light source to ensure the leaf receives maximum light for photosynthesis. Some plants take it to the extreme and follow the sun as it moves during the day. Sunflowers are the most famous example of these plants, which botanists call phototropism. The rest of the plants are called photosensitive, which means they respond to light. The stems of these plants try to grow in the direction of the light source.
Think of a garden plant that grows in the shade, and when light hits it, it stimulates the stem to secrete a growth hormone called auxin. These auxins cause parts of the stem cells to elongate, forcing them to grow toward sunlight. These are constantly changing throughout the life cycle of the plant.

The seasonal effect

The duration and intensity of sunlight fluctuates with the seasons throughout the year, so plants also adapt to these changing seasons. During summer and spring, with plenty of light, most plants focus on growing, blooming, and bearing fruit. As winter approaches, plants will focus more on conserving energy and growing less when light intensity and duration decreases. Photosynthesis decreases in the fall, and leaves begin to lose chlorophyll. This is why the leaves tend to turn brown, yellow or red in the fall.