Impacts of LED interlighting on the growth, yield, and quality of hydroponic greenhouse tomatoes
Date
2018
Authors
Burns, Tara Nicole, author
Uchanski, Mark, advisor
Pilon-Smits, Elizabeth, committee member
Newman, Steven, committee member
Journal Title
Journal ISSN
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Abstract
Recent technological advances have lead to light emitting diode (LED) lights becoming more readily available. They are becoming established as a way to supplement light in controlled environment crop production and are typically used as a top light. Due to their unique characteristics, LED lighting infrastructure and the lights themselves can also be placed within the canopy (interlighting bars); a location that has typically been hard to reach with traditional high-pressure sodium or ceramic discharge lamps. Currently, there is little research on the overall effects of interlighting on plant growth and productivity. Therefore, four studies were conducted to measure the impacts of interlighting on the growth of hydroponically grown greenhouse tomatoes. Interlighting was evaluated for a 16:8 photoperiod (light:dark) under both naturally increasing and decreasing daylengths. Tomato plants were grown in perlite and trained to a single leader on an overhead support system. Flowers were hand pollinated twice a week to ensure fruit set. Data collected included vegetative biomass, individual fruit weight, total fruit yield, soluble solids content, pH, and leaf gas exchange to assess tomato vegetative and reproductive growth and physiological parameters. In addition, the photosynthetically active radiation (PAR) output of the interlighting was measured to create a light distribution map. Lastly, a distance experiment was conducted to measure the effects of the proximity of the interlighting bars on early tomato vegetative growth. Across three experiments we observed that interlighting significantly increased gas exchange measurements (i.e. photosynthetic rate) in individual lighted leaves, however, overall vegetative growth and fruit yield did not increase. Although individual leaves responded to the additional light resource located in the canopy, it did not significantly increase overall yield on quality of greenhousegrown tomato fruits.