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Physiology, Photochemistry, and Fitness of Mexican Maize Landraces in the Field

Pace, Brian A.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1545421491370678

Abstract Details

2019, Doctor of Philosophy, Ohio State University, Horticulture and Crop Science.
Climate change impacts crop production as mean and extreme temperatures increase. Yet the maintenance of crop yield depends on the continued adaptation of crop varieties to their local environments. Mexico, the crop center of origin for maize, is home to high genetic diversity in landraces that campesino farmers actively manage, conserve, and rely upon. Southern Mexico possesses strong elevation gradients and heterogeneous environments cover a relatively small area, creating an ideal study site. The overall objective of this dissertation is to explore patterns of local adaptation in maize landraces along an elevation gradient while investigating the underlying physiological mechanisms which may explain these patterns. Populations of maize landraces from two elevation gradients (600-2150 m and 1850-2400 m) were compared in common gardens over three field seasons. In the first two years, 12 populations were sourced from, and planted reciprocally into, three elevational zones (600, 1550 and 2150 m). We studied traits such as photosynthetic rate, stomatal conductance, stomatal density, and relative growth rate (RGR), some of which proved to influence landrace maize fitness. Maize fitness was affected by G x E interactions, with responses of maize from different elevations (G) responding differently across common gardens (E). Evidence for local adaptation for both years was accompanied by strong to year to year variation. In the third year, 14 populations were collected every 100 m and planted at three elevations (1850, 2100, and 2400 m), and seven additional populations were sourced from genebank accessions originating in four Mexican states. We evaluated the quantity and diversity of leaf flavonoids, which are secondary plant metabolites that serve as protectants from UV-B damage. Two flavonoids varied based on garden elevation and are known to be herbivory deterrents. Maize landraces sourced within several 100 m often performed similarly, but maladaptive genetic variation at the population level may explain where this was not the case. The level of adaptation of maize landraces to current environments and their ability to respond plastically to new environments is likely to predict their continued use and conservation by farmers.
Kristin Mercer (Advisor)
162 p.
Biochemistry; Climate Change; Conservation; Ecology; Evolution and Development; Physiology; Plant Biology; Plant Sciences
maize; Zea mays; landraces; fitness; local adaptation; phenotypic plasticity; plant physiology; climate change; genetic resources; genetic conservation; ethnobotany; secondary metabolism; flavonoids; photosynthesis; stomatal conductance; stomata

Recommended Citations

Citations

  • Pace, B. A. (2019). Physiology, Photochemistry, and Fitness of Mexican Maize Landraces in the Field [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1545421491370678

    APA Style (7th edition)

  • Pace, Brian. Physiology, Photochemistry, and Fitness of Mexican Maize Landraces in the Field. 2019. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1545421491370678.

    MLA Style (8th edition)

  • Pace, Brian. "Physiology, Photochemistry, and Fitness of Mexican Maize Landraces in the Field." Doctoral dissertation, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1545421491370678

    Chicago Manual of Style (17th edition)

osu1545421491370678
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This open access ETD is published by The Ohio State University and OhioLINK.