Effect of LED Lighting on Morphogenesis and Content of Ascorbic Acid, P, K, and Ca in Eruca sativa Plants

The effect of light emitting diode (LED) light sources with different spectra on Eruca sativa Mill., cv. Dikovina plant development was investigated. Experiments were conducted with four types of LED lamps of our own assembly: solar box (SB), red-green-blue (RGB), red-blue (FS), and warm white (WW) used as a control with an energy ratio in the blue-green-red range of 14% : 48% : 38%. Spectra of SB (26% : 41% : 33%), RGB (32% : 19% : 49%), and FS (27% : 11% : 62%) lamps were used to obtain nine different types of lighting ensuring modification of spectra in the course of growing. The plants exposed to FS-RGB, SB-FS, and RGB-SB light sources were characterized with the greatest values of the shoot fresh weight. Transfer of plants to SB resulted in a decrease in development of the plants root system. Transformation of leaf mesostructure after transfer to SB showed that light conditions therein promoted the formation of leaf structure with lower membrane indexes and deformed mesophyll cells. At the same time, cultivation of plants for 2 weeks in SB with subsequent transfer to FS for 4 more weeks stimulated development of internal assimilatory surface of the leaf with the greatest integral indexes of the outer membrane surface of leaf cells (A(mes)/A) and chloroplasts (A(chl)/A) as compared with other treatments. As a result, SB-FS plants produced maximal dry shoots and roots biomass. Without alteration of the lighting pattern, plants from box FS were inferior to control plants (module WW) in parameters of leaf mesostructure and ranked second among other types of treatment. The greatest accumulation of P and Ca was observed in FS-RGB where a maximal percentage of shoots and roots dry matter and the greatest concentration of ascorbic acid were found. Transfer of plants from other boxes to FS caused a decrease in accumulation of macroelements in E. sativa plants. Thus, the dynamic lighting applied for growing of E. sativa plants affected their characteristics and could be used for optimization of plant cultivation.