LED Lightning
Written by:
Mathieu Beaucage,
Agricultural Technician
Ever since agriculture became part of the lifestyle of the first great civilizations, the sun has been the main source of light for plant growth. This luminous star provides a quantity of light that can be assimilated by the plant's chloroplasts, enabling it to acquire the energy it needs to develop. In food production, whatever the techniques is being employed, the amount of light received by plants is fundamental to the success of the growth cycle, and consequently to the final yield. The more light plants receive, the more they will be able to synthesize sugars, via CO2 taken from the air, which will enable them to grow, develop and build up energy reserves in the form of starch, in order to continue their development after the high season.
Over time, scientists have studied the different types of light sources available, as well as their effects on plant growth and development. The sunlight contains the entire spectrum of luminous wavelengths. However, when plants are exposed to the sun's rays, they absorb only a fraction of this light energy. Specifically, the wavelengths coming from photo-synthetically active radiation, commonly referred to in the scientific community as PAR. PAR contains mainly blue, green and red wavelengths, being the only wavelengths in the light spectrum that are useful for photosynthesis. Green light is poorly absorbed by chlorophyll photoreceptors, while red light prevents its degradation and influences plant size, flowering and seed formation. An abundance of blue light, on the other hand, increases metabolism, accelerating plant growth and development while preventing the multiplication of leaves around fruit. A lack of the latter would have negative results on a crop, which would then suffer significant losses.
In the case of a crop illuminated by an LED-type source, there are categories of light capable of emitting wavelengths containing all the light spectrums, just like the sun, but at a lower intensity. However, the LED lighting found in greenhouses and technological agricultural installations does not always contain the full spectrum of light. In fact, the lights used may contain only blue and red wavelengths, having effects on plant physiology and enabling growers to control certain aspects of growth and development to obtain precisely the required product quality.
It is advantageous to use this type of light to adapt the luminous intensity and wavelength ratios required according to the growth stage of the plants. When more blue light is absorbed, this has a direct impact on vegetative and leaf growth, but more importantly, it results in stockier plants due to the reduced space between the plant's internodes. However, when red light is predominantly used, the plant will branch out more and increase the volume of its stems. In short, the predominantly blue light will produce stockier plants and will be very useful for limiting the wasting of young seedlings at the start of production, while the presence of red light will be very useful for the plant's growth and flowering.
In short, it's important to remember that you need to strike the right balance in the proportions of these two types of light to be able to achieve the desired cultivation results, which is why LED lights are indispensable for new cultivation technologies. The wide range of possibilities offered by the use of these light sources in the agri-food sector gives precise control over the environment in which plants grow, and consequently over the quality and homogeneity of the products that will end up on grocery shelves before ending up into consumers' plates.
