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Diurnal manipulation of row covers within high tunnels during spring and fall and its influence on the growth, composition and visual appeal of red lettuce (Lactuca sativa)

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2019, Master of Science, Ohio State University, Horticulture and Crop Science.
Detailed study in highly controlled environments has helped explain the influence of light and temperature on lettuce primary productivity and secondary metabolite levels, but in conditions largely unrepresentative of horticultural environments that are relevant to an increasing number of growers. Responses of crops grown in fall and spring high tunnels are particularly under-studied. Ambient temperature and light conditions in mid-to-upper latitudes during this time are dynamic and extreme. Within high tunnels, sub- and supra-optimal light and temperature levels, especially in combination, are common. Aerial covers, used continuously and selectively applied at night, within high tunnels can both mitigate and potentially create more extreme microclimates, with unknown effects on leafy green quality and visual appeal (i.e. pigmentation). Plant outcomes when manipulating light and temperature conditions near lettuce crop canopies using aerial coverings over set hours each day in northern climate shoulder seasons are underreported, although their implications for crop physiology, horticultural business and human nutrition are large. In these studies, we investigated the impact of aerial covering regimens within spring and fall high tunnel environments on red lettuce (Lactuca sativa) productivity, quality and sensory appeal. Beds were seeded with `Outredgeous’ red lettuce in a 9.1 m x 24.4 m high tunnel in Wooster, Ohio in Fall 2017, Spring 2018, Fall 2018 and Spring 2019. The four covering treatments. utilizing 0.0279-mm thick vented polyethylene film and/or heavyweight row cover (50-AG Agribon), were as follows: (1) covered with film always and row cover at night (“F-RC”); (2) covered with film always (“F”); (3) covered with row cover at night (“RC”), and; (4) uncovered (“U”). Measurements of fresh and dry weight, leaf area, total soluble solids (⁰Brix), and total anthocyanin concentration (Week 7 only) were collected four and seven weeks after treatments were applied. Environmental data were recorded seeding to harvest. Sensory panels were conducted in Fall 2018 and Spring 2019, using material collected at Week 7. Panelists were asked to differentiate treatment samples based on color and rank samples according to leaf color intensity and color distribution, then indicate their preference for treatment samples included in a mesclun mix using a hedonic scale. Each covering regimen resulted in a distinct diurnal temperature profile based on average maximum and minimum temperatures and cumulative growing degree days. Film covering treatments (F-RC and F) had a negative effect on anthocyanin concentrations and positively correlated with growth (FW, LAI) at both samplings compared to the control. Nightly row cover (F-RC and RC) treatments increased fresh weight and leaf area compared to beds without (F and U) in fall runs. In triangle tests, panelists responded correctly in all but one treatment comparisons (F vs F-RC) across both seasons; samples in all other comparisons could be differentiated visually. U and RC treatments were ranked as more intensely and evenly red than F and F-RC treatments. Panelists indicated a similar liking for all samples when included in a mesclun mix. Lessons from this work include: (a) daily covering regimens affect yield, composition and pigmentation of leaves; (b) while consumers can differentiate between samples visually, they did not show a strong preference for any covering regimen when incorporated into a mix, as baby red lettuce is commonly marketed.
Matthew Kleinhenz (Advisor)
Joseph Scheerens (Committee Member)
Chieri Kubota (Committee Member)
103 p.

Recommended Citations

Citations

  • HIlfinger, D. (2019). Diurnal manipulation of row covers within high tunnels during spring and fall and its influence on the growth, composition and visual appeal of red lettuce (Lactuca sativa) [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563350125786694

    APA Style (7th edition)

  • HIlfinger, Dana. Diurnal manipulation of row covers within high tunnels during spring and fall and its influence on the growth, composition and visual appeal of red lettuce (Lactuca sativa). 2019. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1563350125786694.

    MLA Style (8th edition)

  • HIlfinger, Dana. "Diurnal manipulation of row covers within high tunnels during spring and fall and its influence on the growth, composition and visual appeal of red lettuce (Lactuca sativa)." Master's thesis, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563350125786694

    Chicago Manual of Style (17th edition)