Optimal ratio of spectrum, light intensity and photoperiod to minimize costs when growing microgreens

Abstract

The paper considers the influence of spectrum and light intensity/photoperiod ratio on the energy intensity of production and financial costs of consumed electricity. This influence is caused not only by the yield obtained, but also by the different energy efficiency of lightemitting diodes of different spectrum and the price of electricity at different hours of the day. Considering the influence of the spectrum, it was found that the costs decrease with increasing the proportion of red light for all microgreen varieties under consideration. Laboratory studies were carried out on microgreens of cabbage of the “Mitsuna” variety and radish of the “Octave” variety. A long photoperiod at low intensity is better than a short photoperiod and high light intensity in terms of energy and financial efficiency. Combining the results on dry weight as a quality indicator, energy consumption and financial cost per fresh weight, we consider a lighting system with parameters B:R:FR=29:58:13%, PPFD= 100 μmol·m-2·s-1 / 16 h as the preferred option for growing microgreens.