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Walden _ Final Thesis Draft.pdf (2.75 MB)

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Time-Dependent Microclimate Effects on Yield and Anthocyanin Levels of Lettuce (L. sativa) and Choi (B. rapa var. chinensis)

Walden, Susan
http://rave.ohiolink.edu/etdc/view?acc_num=osu1511898465276836

Abstract Details

2017, Master of Science, Ohio State University, Horticulture and Crop Science.
The tradeoff between primary and secondary metabolism can create a conflict between grower and consumer interests. Primary metabolism utilizes the products of photosynthesis for growth and biomass accumulation while secondary metabolism utilizes these products for the production of phytochemicals, such as anthocyanin. While the focus for growers is typically on high yield, consumer interest in colorful vegetables with high levels of health-beneficial secondary compounds is increasing. Promoting both primary and secondary metabolism within the same cropping cycle can benefit both growers and consumers in multiple ways. This process can be difficult, however, perhaps especially in fall-to-spring high tunnel production in the mid to upper latitudes known for dynamic and often limiting temperature and light conditions. Season extension technology, such as low tunnel coverings, can alter the near-crop environment and create conditions more suitable for growth. This research examined the extent to which aboveground biomass and anthocyanin concentrations are affected by low tunnel microenvironments imposed during specific portions of baby lettuce and choi production cycles. The experiment was repeated October-December and February-April in 2015-2016 and 2016-2017 in a single-layer, 9.1 m x 24.4 m high tunnel located at the Ohio Agricultural Research and Development Center in Wooster, OH. Twenty, 4.46-m2 main plots were divided into 2.23-m2 subplots, each containing either `Outredgeous’ lettuce (Lactuca sativa) or `Red Pac’ choi (Brassica rapa var. chinensis) direct-seeded at 3,875 seeds/m2 on 10/9/15, 2/16/16, 10/7/16, and 2/21/17. Each subplot was assigned to one of five treatments based on when they were covered with standard, vented (178 1-cm holes/m2), 1.1 mil polyethylene film: 1) uncovered all 8 weeks, 2) covered first 4 weeks, 3) covered middle 4 weeks, 4) covered last 4 weeks, and 5) covered all 8 weeks. Analyzed digital images obtained biweekly assisted in calculating percent canopy cover and plant density. Air temperatures were recorded at canopy level every 15 minutes using Hobo U23 Pro v2 External Temperature Data Loggers. Destructive sampling of a 0.093-m2 quadrat within each subplot at 2, 4, 6, and 8 weeks after seeding permitted the measurement of fresh and dry weight, anthocyanin concentration, soluble solids, leaf area, and average daily growth rate. Significant differences were dependent on experimental run but where differences occurred, yield was generally higher for treatments 4 and 5, lower for treatments 1 and 3, and moderate for treatment 2. Conversely, anthocyanin concentrations were highest for treatments 1, 2, and 3 and lowest for treatments 4 and 5. Subsequent nutritional yield, a function of biomass and anthocyanin concentration, was higher for treatments 2 and 5. Overall, these data indicate that the timing of certain microenvironments within the cropping cycle likely affect the processes underlying the relative accumulation of aboveground biomass and anthocyanin.
Matthew Kleinhenz, PhD (Advisor)
94 p.
Horticulture
Anthocyanin; lettuce; choi; high tunnel; low tunnel; GDD; DLI; nutritional yield

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Citations

  • Walden, S. (2017). Time-Dependent Microclimate Effects on Yield and Anthocyanin Levels of Lettuce (L. sativa) and Choi (B. rapa var. chinensis) [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1511898465276836

    APA Style (7th edition)

  • Walden, Susan. Time-Dependent Microclimate Effects on Yield and Anthocyanin Levels of Lettuce (L. sativa) and Choi (B. rapa var. chinensis). 2017. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1511898465276836.

    MLA Style (8th edition)

  • Walden, Susan. "Time-Dependent Microclimate Effects on Yield and Anthocyanin Levels of Lettuce (L. sativa) and Choi (B. rapa var. chinensis)." Master's thesis, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1511898465276836

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.
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