What’s the effect for plants by lighting?
Light plays a particularly important role in the growth and development of plants. It affects almost all growth stages of plants. The effect of light on plants is mainly two aspects: Providing radiant energy for plant photosynthesis; and it many physiological processes in the whole life cycle of plants. That’s why the LED Grow Light is the most popular in the market for indoor plant growing, like greenhouse .commercial cannabis growing etc.
Photosynthesis refers to the process that green plants use light energy through chloroplasts to convert carbon dioxide and water into organic matter storing energy and release oxygen. The key participants in this process are chloroplasts inside plant cells. Under the action of sunlight, chloroplasts convert the carbon dioxide entering the leaf through the stomata and the water absorbed by the root into glucose, and release oxygen at the same time.
The light system of light reaction is composed of a variety of pigments, such as chlorophyll a, chlorophyll b, carotenoids and so on. The main absorption spectra of chlorophyll a, chlorophyll b and carotenoids are concentrated at 450nm and 660nm. Therefore, in order to promote photosynthesis, the combination of 450nm dark blue LED, 660nm ultra red LED and some white LED is mainly used to realize efficient LED plant lighting,
In order to perceive the light intensity, light quality, light direction and Photoperiod of the surrounding environment and respond to their changes, plants have evolved a light sensing system (light receptor).
Photoreceptor is the key for plants to feel the changes of external environment. In plant light reaction, the main photoreceptor is phytochrome which absorbs red / far red light.
Phytochrome is a kind of pigment protein that can reverse the absorption of red light and far red light, participate in light morphogenesis and regulate plant development. It is extremely sensitive to red light (R) and far red light (FR), and plays an important regulatory role in the whole process of plant growth and development from germination to maturity.
Phytochrome in plants exists in two stable states: red light absorption type (PR, Lmax = 660nm) and far red light absorption type (PFR, Lmax = 730nm). The two light absorption types can reverse each other under the irradiation of red light and far red light.
Studies related to phytochrome show that the effects of phytochrome (PR, PFR) on plant morphology include seed germination, de yellowing, stem elongation, leaf expansion, shade avoidance and flowering induction.
Therefore, a complete led grow light scheme requires not only 450nm blue light and 660nm red light, but also 730nm far red light. Dark blue light (450nm) and ultra red light (660nm) can provide the spectrum required for photosynthesis, and far red light (730nm) can control the whole process of plants from germination to vegetative growth and then to flowering.