Date of Award

January 2015

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Horticulture and Landscape Architecture

First Advisor

Cary A Mitchell

Committee Member 1

Mario G Ferruzzi

Committee Member 2

David Rhodes

Abstract

While generally viewed within the context of plant growth and development, different qualities of light are also powerful elicitors of secondary metabolic pathways in plants that affect the nutritional value and flavor of edible tissues. Leveraging fundamental photobiology principles, our studies sought to use different qualities of supplemental light including ultraviolet-B (UV-B), UV-A, blue, red, and far-red as an environmental treatment to restore garden-grown flavor and nutritional attributes to greenhouse-grown tomatoes (Solanum lycopersicum); a commercially important crop that has a poor reputation compared to its garden-grown counterparts. To test our hypotheses, we used a battery of physicochemical analyses that included total soluble solids, citric/ascorbic acid content, pH, and electrical conductivity of tomato fruits. Additionally, phenolic compounds in fruit tissues were quantified broadly using the Folin-Ciocalteu method and specific flavonoids were quantified with a more targeted approach using HPLC-ESI (-)-MS. Lycopene and β-carotene were quantified spectrophotometrically. In one study, qPCR was used to quantify genes involved in light-signal transduction in order to better understand the molecular underpinnings of plant UV-B perception. Two studies included consumer sensory panels to assess the impact of supplemental light quality on

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