Physiology Characterization of Nitrogen Use in Maize: Opportunities for Improvement
Uribelarrea, Martin
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https://hdl.handle.net/2142/85033
Description
Title
Physiology Characterization of Nitrogen Use in Maize: Opportunities for Improvement
Author(s)
Uribelarrea, Martin
Issue Date
2007
Doctoral Committee Chair(s)
Below, Frederick E.
Department of Study
Crop Sciences
Discipline
Crop Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Plant Physiology
Language
eng
Abstract
Nitrogen supply plays a key role in yield determination of the maize crop. An adequate supply of N is vital for the proper establishment and maintenance of the photosynthetic capacity, and for the determination of sink capacity and maintenance of that sink throughout seed development. Since N is one of the main factors powering yield, annual applications of fertilizer N are the norm. However, growing concerns about the environmental impact of crop productivity, together with increasing costs of fertilizer N necessitates a better understanding of processes associated with the efficiency of N use (NUE) and their importance in designing crop management strategies and in developing breeding programs for improved N use. The overall objective of this work was to identify and characterize physiological N response traits that are under genetic control and that can be used to improve NUE. Specific objectives included: (1) gaining a better understanding of how N is utilized by the plant to produce yield, (2) characterizing the genetic diversity for N use in maize hybrids; and (3) determining if N use traits can be identified and improved in maize inbreds. The overall approach was to evaluate maize genotypes (commercial and experimental hybrids and inbreds) under various levels of N supply ranging from deficient to excessive under field conditions. Results within each specific objective suggest that: (1) PEPc may serve as a storage sink for excess leaf N, and that a better allocation of N into Rubisco could improve maize photosynthesis, (2) No hybrid (commercial or experimental) was optimized for both N uptake and N utilization which suggests room for improvement in NUE for maize; and (3) Introgression of exotic germplasm, nearly always improved NUE of the hybrids, which was largely due to improved uptake efficiency. Overall, results presented in this work, provide a better understanding on how N is utilized for yield generation in the maize plant, and provides useful information on possible strategies to be incorporated in breeding programs aimed at N use improvement.
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