In the next decade, a 3% increase in agricultural production is expected in Western Europe, without increasing the cultivated area, which implies the use of right quality seeds, fertilizers and other technologies to increase the production (OCDE/FAO, 2018), while the regulatory bases are increasingly strict. Cultivation without soil together with the use of LED with customized spectra, allows the control of all parameters that influence the physiological and morphological growth of the crop. Many studies have exposed the effects that blue and red light has on plant growth, but less are those that talk about the effect of other wavelengths not only in physiologic but also in nutritional growth. This work aims to study the effect of the interaction between various lighting variables, in a controlled environment, such as: the spectrum (using 4 different light spectra, 3 of which are specific for plant cultivation), intensity (2 or 4 lamps) and the photoperiod (16 or 24 hours of light exposure) in the nitrate content at the end of the growth of Chycorium intybus microgreens, of the purple oak leaf lettuce variety. Trying to clarify in some way which one is the most favourable light treatment for the cultivation of microgreens of this variety and therefore the one that generates healthier seedlings for human consumption. It was obtained that the most favourable light treatment for a lower nitrate concentration is the VEG spectrum, which is one of the specific spectra for agricultural cultivation, with an intensity of 4 lamps and a 24-hour photoperiod. This same spectrum generated significantly different results from the rest of treatments in 2 of its 4 possible combinations between intensity and photoperiod. There was a clear tendency to accumulate fewer nitrates in those treatments that, regardless of the spectrum and intensity, were grown under a 24-hour photoperiod.
