Controlled environment agriculture, which includes indoor farming and vertical farming, has gained traction in India over the last few years. With this development, the importance of the lighting environment for plant growth has become increasingly apparent. While sunlight provides a full spectrum of light, creating an optimal artificial light environment requires a deeper understanding of how different light wavelengths impact plant growth and development.
Perhaps the most exciting feature of LED grow lights is the ability to adjust the light spectrum. Depending on the specific needs of a plant species or growth phase, growers can increase or decrease the amount of blue, red, green, or far-red light the plants receive. The UV light can also be adjusted to optimize plant growth. This ability to tailor the light environment can enhance growth rates, improve plant quality, and increase yield.
Visible light, the portion of the electromagnetic spectrum that humans and plants can see, ranges from about 400 nanometres (nm) to 700 nm. Different wavelengths within this spectrum, each correlating to a different colour, have unique effects on plants.
Blue light, in the 400 to 500 nm range, is vital for plant growth as it promotes vegetative leaf growth. Blue light regulates plant growth, influencing phototropism—the process by which plants grow towards their light source. Additionally, it impacts chlorophyll production, essential for photosynthesis.
Red light, between 600 and 700 nm, stimulates flowering and fruit production, contributing to overall plant yield. It's a key player in photosynthesis, supporting energy production within the plant.
Green light, within the 500 to 600 nm range, several research and experiments have proven the green spectrum is equally efficient in driving photosynthesis as blue or red light. Green Light can penetrate deeper into the plant canopy, potentially benefiting lower leaves that typically receive less light. It also influences plant color perception and plant architecture.
Far-red light, from 700 to 800 nm, while not visible to humans, is perceived by plants. It influences the timing of flowering and other photoperiod-dependent physiological responses. Studies on effect of Far-RED on leafy greens have found this light band to produce longer and wider leaves which is a desirable characteristic for leafy green crops.
Ultraviolet (UV) light, ranging from 100 to 400 nm, is typically divided into three types: UVA, UVB, and UVC. UVC is the most harmful and is almost completely absorbed by the Earth's atmosphere. UVA and UVB reach the Earth's surface and can impact plant growth. UV light can stimulate the production of protective pigments, improve taste and aromas, and increase plant disease resistance. However, excessive UV light can be harmful, causing damage to plant tissues and impeding growth.
Read more about how FAR-RED light can be beneficial for the plant growth.