LEDs Create a Less Stressful Light Environment and Increases in Higher-energy Blue Wavelengths will Increase Production of Nutritionally Important Metabolites in Specialty Vegetable Crops

Light is one of the most important environmental stimuli impacting plant growth and development.  Plants have evolved specialized pigments to capture light energy to drive photosynthetic processes, as well as respond to changes in light quality and quantity.  Blue light can act as a powerful environmental signal regulating phototropisms, suppression of stem elongation, chloroplast movements, stomatal regulation, and cell membrane transport activity.  An emerging application of light-emitting diode (LED) technology is for horticultural plant production in controlled environments.  Work by our research group is measuring important plant responses to different wavelengths of light from LEDs.  Using brassica species as model crop systems, we have demonstrated dramatic impacts of primary and secondary metabolism in microgreen and baby leafy green crops.  Results show significantly increases in shoot tissue pigments following exposure to higher percentages of blue LED wavelengths.  Significant positive correlations among NPQ and leaf tissue zeaxanthin concentrations also demonstrate LEDs provided a less stressful light environment.  LED lighting with higher percentages of blue wavelengths will also significantly increase shoot and root tissue essential mineral element concentrations.  Working with brassicas, we have also shown blue LED wavelengths to significantly increase nutritionally important glucosinolate compounds.  The perception of energy-rich blue light by specialized plant photoreceptors will trigger a cascade of metabolic responses.  Results from our research clearly show stimulation of primary and secondary metabolite biosynthesis following exposure to blue LED wavelengths.  Management of the light environment may be a viable means to improve the nutritional contributions of specialty vegetable crops.