The Influence of LED Lights of Different Spectra on the Development of Lactuca sativa

The effect of light-emitting diode (LED) lamps with five different spectra on L. sativa plants (variety Aficion) grown in protected soil conditions was studied. Warm white light (WW) was used as the control (the ratio of blue, green, and red portions in the spectrum was 14 : 48 : 38%). The maximum values of the leaf size and the fresh weight of the aerial parts were found in the RGB group (blue–green–red ratio 32 : 19 : 49%), and the highest values of the dry weight and ash content were in the FS group (blue–green–red ratio 27 : 11 : 62%). The stomatal size and density on the abaxial side of the leaf was the highest in SB plants (blue–green–red ratio 33 : 41 : 38%). This was the most effective combination of parameters in terms of leaf architectonics. An increase in the portion of red light in the spectrum with a decrease in the portion of green light had a positive effect on the development of L. sativa plants, while an increase in the portion of green light in the spectrum positively affected the formation of the stomatal apparatus.