Light is the most important factor affecting the growth of plant. From seedling stage to flowering stage, light affects the growth, structure, and color of leaves.
Intensity of light influences the production of plant food, length of stem, leaf color and flowering of plant.
Plants which are grown in low light are spindly in structure with light green leaves. A similar plant grown in direct sunlight is shorter, has better branches, and has larger, dark green leaves.
Direction of Plant Growth
When the first leaves of plants appear, they try to grow towards the sun to receive maximum light for photosynthesis.
When the light shines on a plant part, it stimulates the secretion of auxins from that part and makes the stem cells elongate and grow towards the sunlight.
Light Spectrum
Light is made of electromagnetic waves and we are only able to see visible light ranges from 390-700nm in wavelength.
When scattered, this visible light makes a seven-color band which is known as VIBGYOR or ROYGBIV.
Blue light – With a wavelength of 400-500nm, this light has high energy, which is good for the leaf growth of plants.
Red Lights—With low energy and a wavelength of 600-700nm, it is important for blooming or flowering plants.
Supplemental Lights
In an indoor system, we pick supplemental lights to fulfil the following three factors:
- The intensity of light or how much energy in the form of light photons is falling on plant leaves determines the rate of photosynthesis. The greater the intensity of light, the more photosynthesis will occur in plants.
- The duration of light also influences the growth and flowering of plants, which is known as photoperiodism. On the basis of photoperiodism, plants are classified as long-day plants and short-day plants.
Long-day plants require more than 12 hours of daylight, while short-day plants require less than 12 hours of daylight for flowering.
- Plants require both the red and blue spectrum of light at different stages of plant life for leaf or vegetative growth and for blooming or flowering.