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Integration of root phenes affecting nitrogen acquisition in maize

Author
York, Larry
Published
[University Park, Pennsylvania] : Pennsylvania State University, 2014.
Physical Description
1 electronic document
Additional Creators
Lynch, Jonathan P.
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Open Access.
Summary
Food insecurity is among the greatest challenges humanity will face in the 21st century. Agricultural production in much of the world is constrained by the natural infertility of soil which restrains crops from reaching their yield potential. In developed nations, fertilizer inputs pollute air and water and contribute to climate change and environmental degradation. In poor nations low soil fertility is a primary constraint to food security and economic development. Increasing the acquisition efficiency of soil resources is one method by which crop yields could be increased without the use of more fertilizers. Maize is one of the most widely grown crops, both in terms of land area and in yield, so optimizing uptake efficiency of maize is an important goal.Roots are the primary interface between plant and soil and are responsible for the uptake of soil resources. The deployment of roots in space and time comprises root system architecture (RSA). Maize RSA is a complex phenotype that aggregates many elemental phenes (elemental units of phenotype). Integration of root phenes will be determined by interactions through their effects on soil foraging and plant metabolism. Many architectural, metabolic, and physiological root phenes have been identified in maize, including: nodal root number, nodal root growth angle, lateral root density, lateral root length, aerenchyma, cortical cell size and number, and nitrate uptake kinetics.The maize root system is composed of an embryonic root system and nodal roots that emerge in successive whorls as the plant develops. Current phenotyping platforms often ignore the inner whorls and instead focus on the most visible outer whorls after excavating a maize root crown from soil. This dissertation researches the RSA among whorls of the maize nodal root system and demonstrates how the variation with the root crown could have functional significance. Nodal root number was decomposed to more elemental phenes including the number of nodes and the occupancies of each node. Simulations demonstrated that root systems forming fewer nodal roots and with delayed emergence perform well in low nitrogen soils. Nitrate uptake kinetics (NUK) vary within the maize root system, and simulations showing a lack of interaction between NUK and RSA reflects a knowledge gap in the costs of NUK at the molecular level. Finally, maize RSA among hybrids from different era periods over the past 100 years suggests evolution towards more nitrogen efficient states.
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Dissertation Note
Ph.D. Pennsylvania State University 2014.
Reproduction Note
Microfilm (positive). 1 reel ; 35 mm. (University Microfilms 36-90178)
Technical Details
The full text of the dissertation is available as an Adobe Acrobat .pdf file ; Adobe Acrobat Reader required to view the file.
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