The influence of colours on plants
Numerous research and tests show that the radiations of red and blue light spectra form the most efficient wavelengths for the production of plants’ chemical energy.
Insufficient illumination or an inappropriate composition of different wavelengths have anomalous consequences or may even be harmful for plant growth.
Lighting initiates photochemical reactions: humans react to light stimulation with photoreceptors which show peaks of light absorption at 555 nm (S, M, L); in plants, instead, photosynthetic efficiency is primarily guided by chlorophyll a and b. Peaks of light absorption of chlorophyll a are at 665 nm and 465 nm.
The sunlight intercepted by chlorophyll a and b that is actually available as energy for the photosynthesis is called Photosynthetic Active Radiation (PAR) which corresponds to 41% of the total sun radiation and concentrates within the blue and red wavelengths, with peaks at 430 nm and 680 nm..
This region includes the following sub-regions:
- blue-violet (400-490 nm), absorbed by pigments used for flowering, protein synthesis, phototropic effects, average effect on the photosynthesis
- green (490-560 nm), the least photosynthetically active radiation
- yellow (560-590 nm)
- red-orange (590-700 nm), very photosynthetically active radiation
Effects of LED lighting and advantages of specific spectrum systems
- tailored emission spectrum: ad hoc composition of wavelengths capable of affecting the photomorphogenesis of plants (growth, shape and flowering); the simulation and full control over the various phases of daylight
- faster on/off time: lights get instantly to their full light level; adjustment to daylight changes, ensuring higher energy savings
- longer lamp life: the extremely long service life of the LEDs (over 50000 hours) entails lower maintenance costs and, above all, a quick return on the investment
- supplementary lighting: to provide additional quantity and quality of illumination not achieved with the artificial lighting system in order to improve the photosynthesis and therefore the growth and quality of the plants in greenhouses
- photoperiod regulation: to extend the day length by controlling the period of light
- plant growing in the absence of natural sunlight: to fully replace sunlight and control climate conditions