The Influence of the Spectral Properties of the Lighting Environment on Light Absorption by Lettuce Leaves and the Net Productivity of Lettuce

摘要

—The efficiency of light absorption with different spectral compositions by lettuce leaves and the choice of optimal conditions of the lighting environment for increasing the productivity and quality of plant products grown under artificial lighting conditions were investigated. Lettuce of the Typhoon variety was grown by a thin-layer panoponic method in an automated growth chamber with five variants of different light sources. A non-damaging method developed by the authors for the measurements of the absorption spectra of leaves in vivo made it possible to determine the influence of the spectral composition of the radiation on the optical characteristics that reflect the physiological state of the plants. The amount of absorbed photon energy increased by ~140 μmol ? m~(–2)s~(–1)with an increment in lettuce leaf biomass by 1 g for 10 days under maximum productivity conditions; the values of the light absorption index below 70 μmol ?m~(–2)?s~(–1)corresponded to the samples with minimum results in growth characteristics. The similarity of the spectral characteristics of lighting in the region of photosynthetically active radiation of HPS lamps (High-Pressure Sodium lamps) and LED lamps, which emit yellow light, and almost the same proportion of photosynthetically active photons in the blue, green, and red regions of the spectrum led to the same increment of light absorption in the process of plant development. However, a significant difference in the productivity of lettuce (~50%), as well as the growth, development, and biochemical composition indicated a better effect of the HPS lamps on the properties of the plant culture. The obtained data indicated that the illumination with an intensity of ~25 μmol?m~(–2)?s~(–1)in the range of 400–500 nm, ~150 μmol?m~(–2)?s~(–1)in the range of 500–600?nm, and ~150 μmol?m~(–2)?s~(–1)in the range of 600–700 nm led to high productivity of the lettuce.