THE IMPLEMENTATION OF LED TECHNOLOGY IN ENVIRONMENTAL GROWTH CHAMBERS: PLANT REPONSES, ENERGY EFFICIENCIES AND PRACTICALITY OF GROWTH CHAMBER RETROFITTING

Open Access
Author:
Frechen, Daniel Christopher
Graduate Program:
Horticulture
Degree:
Master of Agriculture
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Robert Berghage Jr., Thesis Advisor
Keywords:
  • energy
  • fluorescent
  • growth chamber
  • LED
Abstract:
Environmental growth chambers are valuable tools in plant research and specialty crop production. These chambers provide an internal environment completely independent of external influences of irradiance, temperature, and humidity. Operators can program a multitude of settings to obtain the desired internal environment. Researchers can investigate a diverse range of plant reactions in growth chambers, including those of light-mediated photochemicals, or pigments. Specialty crop producers can create a stable environment for high value plant material. But regardless of the operator or plant material, one of the largest challenges experienced when using growth chambers is the electrical demands imposed by the lighting technology. Lighting in growth chambers is often a combination of fluorescent and incandescent lamps. This arrangement emits considerable quantities of heat while also consuming significant quantities of electricity. To remove the heat and maintain the stable internal environment, compressors, humidifiers, and other components also command large quantities of electricity. A quickly developing lighting technology, light-emitting diodes (LEDs), holds the potential to greatly reduce electrical consumption in growth chambers. The objective of this research was to investigate the impacts LED lighting has on energy and mechanical demands of a chamber, and to evaluate whether plant material responds as it does under conventional lighting sources. Two growth chambers were utilized over two runs of experiments. During each run, a chamber was retrofitted with two bi-spectral LED units, and the other chamber retained the factory installed lighting of fluorescent and incandescent lamps. Plant samples included Phaseolus vulgaris ‘Fresh Pick’ (bush beans), Raphanus sativus ‘D’Avignon’ (long French radish), and Lolium perrenne ‘Double Eagle’™ (perennial ryegrass). Growth inputs, internal chamber environments, and electrical loads were recorded over 21 days. Overall, plant material responded favorably to both lighting treatments, with a slight advantage in dry weight going to beans germinated in the CONTROL chamber. While under LEDs, plant material experienced more stable PAR, air temperature and humidity, and soil temperature and moisture levels. Lighting in the LED chamber consumed 85% less electricity than lighting in the CONTROL chamber, a 40% decrease in overall electrical consumption of the chamber. The low heat in the LED chamber resulted in lower mechanical stresses on growth chamber components responsible for maintaining the programmed optimal internal environment.