How should the light falling on the plants be measured?

 in Goodxon

The development and feeding of plants is related to the process of photosynthesis, with leaves being the “factory” where food is processed and transformed into glucose. It is in the process of photosynthesis that food is processed and that the plant produces the glucose necessary for its development, through the absorption of carbon dioxide and the release of oxygen. Since lighting is one of the variables that activates the process of photosynthesis, it is important that in each culture the management and control of lighting is done (number of hours of exposure and adequate light spectrum in each phase of plant growth) according to the intended results , lighting can interfere:


  • in production efficiency (eg in the production of strawberries and tomatoes);
  • The healthiest increase in vegetables and their productivity (eg radishes, lettuce and aromatic plants);
  • In the morphology of the plant (height, stem and leaves) in the various stages of its development (medicinal cannabis)


In comparison to humans, plants have a different perception of light. Humans are more sensitive to green light. The human eye uses special photoreceptors to characterize light in terms of intensity and color. These photoreceptors are very sensitive to green wavelengths and much less sensitive to blue and red wavelengths.

The lighting measurement at the human eye level is performed using the Lumen (lm) model, which is the international measurement unit adopted to measure the total amount of light visible by the human eye that a light source is capable of generating. In other words, it is the measure used to measure the luminous flux, whether natural or not. Lux (lumen / m²) is the measure of intensity used to characterize the number of lumens distributed over a surface of 1 m².,

Unlike the human eye, plants have a much broader sensitivity, and use all the wavelengths of light in the PAR (Photosynthetically Active Radiation) model between 400 and 700 nanometers (nm), which are essential for photosynthesis. The measurement of the PAR lighting spectrum in plants is done through the density of photosynthetic photon flux (PPFD - Photosynthetic Photon Flux Density), measured through the number of units in µMol / m2 / s. (micromoles per square meter per second).


As plants are more sensitive to blue and red, measurements in lumens and lux should not be used to characterize natural or artificial light in the greenhouse / indoor area, but PPFD should be considered through the number of units in µMol / m2 / s in each project in the cultivation area concerned, and considering the desired results and the plant's growth phase. Goodxon assists its customers in the study necessary to obtain the best lighting for each stage of plant growth (germination, vegetation, flowering).

Soon we will develop more news about the effect of each type of light on plants at each stage of growth.