Photo-biological Effectiveness of PAR for Radish Plant Communities Irradiated Using an LED Source with an Adjustable Spectrum

Abstract

The aim of the current study was to find the most effective spectral modes of irradiation of short-season plants (for example, radish) using a fluorescent LED irradiator with a variable spectrum. The research methodology was based on the species-specific response of plants to the spectral composition of light. Photo-biological experiments were carried out to find effective spectral composition of PAR for cultivating radish communities under stable and variable irradiation modes of electrical lighting. It was shown that under stable irradiation modes, the highest productivity of economically useful radish biomass had been achieved at spectral composition with a maximum of 60 % radiation in the (600–700) nm region in a variable spectral irradiation mode. The variable spectral irradiation mode turned out to be the most effective when the spectral composition with the dominance of red rays was changed to the spectral composition with the dominance of blue rays. There were no significant differences between the best production parameters for stable and variable modes of irradiation of radish plants, which indicates the expediency of choosing the stable spectral mode of irradiation of radish plants as a short-season crop under electrical illumination. The results obtained can be used to select spectral irradiation modes for short-season plants grown under electrical lighting in northern regions and in isolated rooms in various climatic zones using “City-farm” technologies.