Leaves are the main organs for photosynthesis of plants, and the change of the light quality of LED tube lights for growing plants directly affects the growth of leaves.
According to reports, the leaf area of birch seedlings grown under blue light is twice that of red light, and the area of leaf epidermal cells, palisade tissue, sponge tissue and functional chloroplasts are larger than those under white and red light.
The rice seedling experiment also had the same result. Compared with white light, the blue light of LED tube lights for growing plants significantly promoted the widening growth of rice seedling leaves, enlarged the angle between the leaf and the leaf sheath, and made the leaves flat; while the effect of red light was the opposite that it inhibited the widening growth of leaves.
However, some people think that the compound light is more conducive to the growth and development of the leaves. The leaf area of lettuce under the combined light of red, blue and green is the largest, followed by white light, and finally red and blue light. Studies have also shown that increasing the proportion of red light in the compound light of LED tube lights for growing plants has a certain promotion effect on the increase of tobacco leaf area, but the leaf weight of the leaves decreases and the leaves become thinner.
The stomata are the channels for water and oxygen to enter and exit, and are the gateways for plant photosynthesis. Stomatal movement is regulated by many external environmental factors and internal factors, of which light is an important regulating factor.
In both monocotyledonous and dicotyledonous plants, it is found that the blue light of LED tube lights for growing plants can promote the opening of stomata, while green light can reverse this effect. They believe that the reversible reaction of blue and green light leading to the opening and closing of the air puncture may be derived from the two isomerizations of zeaxanthin, namely the physiologically active body that mainly absorbs green light and the inactive body that absorbs blue light.
Different wavelengths of light can regulate the growth of stems by affecting the levels of endogenous hormones in plants. Blue-violet light can increase the activity of indole acetic acid oxidase and reduce the level of auxin (IAA), thereby inhibiting plant growth. At the molecular level, red light promotes cell elongation, while blue light has the opposite effect. In general, the long-wavelength LED grow lights with red light promotes the elongation of the stem, while the short-wavelength light (blue light) inhibits the elongation of the stem.