Title

The assessment of Solanum lycopersicum cv. Micro-Tom tomato fruit antioxidant content and capacity under differing temperatures, irrigation regimes, and light hours

Advisor

Klink, Vincent

Committee Member

Gordon, Donna M

Committee Member

Giesen, James C

Committee Member

Munn, Giselle Thibaudeau

Date of Degree

8-1-2020

Original embargo terms

Complete embargo for 2 years||forever||8/15/2022

Document Type

Dissertation - Open Access

Major

Biological Sciences

Degree Name

Doctor of Philosophy

College

College of Arts and Sciences

Department

Department of Biological Sciences

Abstract

The impacts of climate change on agriculture have been observable for years, particularly with declining yields and reduced productivity. Much research has been performed to examine the relationships between yield and climatic variables, especially temperature and precipitation. By comparison, little research has been conducted to assess the impact that climate change has on the nutrition, particularly the antioxidant content and capacity, of crops. This research project aims to fulfill this knowledge gap. Solanum lycopersicum cv. Micro-Tom plants were cultivated in five growth chambers with different temperatures, hours of light, and watering regimes to simulate different environments. The three temperature regimes were 25°, 32°, and 40°C during the day. The two chosen light durations were 12 and 16 hours (h), and the selected watering frequencies were 3 and 5 days (d). Lycopene and phenolics were quantified via spectrophotometry. Color was assessed via the CIELAB color space, specifically the a* value. The ferric reducing ability of plasma (FRAP) assay assessed the ability of the compounds in each tomato sample to serve as antioxidants. Upon analysis, the highest lycopene concentration (72.68 mg per kg fresh weight) was found in tomatoes exposed to 32°C, three days between irrigation cycles, and 16 hours of light. The highest level of phenolics (0.41660 mg gallic acid equivalent per g fresh weight) was observed in tomatoes exposed to 32°C with three days between watering cycles. The largest a* value (11.21), which corresponds to an intense red hue, was seen in tomatoes exposed to 32°C with 16 hours of light. The greatest level of antioxidant capacity [162.12 micromolar Fe(II)] as measured by the FRAP assay occurred in tomatoes exposed to 32°C with three days between irrigation cycles. Overall, antioxidant content and capacity increased the most at 32°C with three days between watering periods. Photoperiod was unimportant. By varying environmental conditions, “designer crops” with specific antioxidant content can seemingly be produced without genetic manipulation. This work enhances the body of knowledge concerning effects of abiotic stress on food crop antioxidants, which is important given the gravity of climate change.

URI

https://hdl.handle.net/11668/17898

Comments

climate change||tomato||antioxidants

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