Anatomical, physiological, and photomorphogenic responses of lettuce and basil to far-red radiation under sole-source lighting
In recent years, energy saving light emitting diodes (LEDs) have contributed to the profitability and sustainability of controlled environment agriculture (CEA). Furthermore, LEDs have given growers more control over spectral deliverance. The myriad of combinations of light quality and quantity offered by manufacturers has convoluted the approach towards an optimal spectrum. This dissertation examines the benefits of incorporating far-red (FR; λ = 700 – 799 nm) radiation into the quantum distribution provided by electric lamps in sole-source lighting operations growing lettuce and/or basil. Traditionally, FR photons have been excluded from the definition of photosynthetically active radiation (PAR; λ = 400 – 700 nm) due to its abysmal photosynthetic performance when acting independently in a narrow waveband. However, recent research has offered a new opinion on the synergistic nature of FR photons when provided in tandem with traditional PAR photons. To help overcome the negative perception of FR photons, this dissertation highlights experiments that supplement and substitute FR photons in the lighting regime of lettuce and basil. Throughout this research, anatomical, physiological, and photomorphogenic assets of FR radiation are examined to show how they can benefit CEA production.