{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/20592"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/20592","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Physiological role of mixed nitrogen nutrition in enhancing productivity of maize","abstract":"Although the maize (Zea mays L.) plant can utilize either NH$\\sb4\\sp+$-N or NO$\\sb3\\sp-$-N, many studies have shown that mixed N nutrition (NH$\\sb4\\sp+$ + NO$\\sb3\\sp-$) can optimize productivity. However, the physiological processes that are beneficially altered by mixed N have not been elucidated. Therefore, studies were conducted to compare plant productivity traits under mixed N or predominantly NO$\\sb3\\sp-$ nutrition. Mixed N nutrition enhanced early season leaf area and leaf number, stimulated post-anthesis nitrate reductase activity, and lessened late-season chlorophyll degradation. Although NO$\\sb3\\sp-$-grown plants had equivalent or greater rates (approximately 5 to 10%) of canopy photosynthesis (P$\\sb{\\rm s}$) than mixed N plants, the duration of P$\\sb{\\rm s}$ was unaffected by N-form treatment at photosynthetic photon flux densities of 900, 1800 or mathematically integrated from 600 to 2100 $\\mu$mol photon m$\\sp{-2}$ s$\\sp{-1}$. Despite the lowered rates of P$\\sb{\\rm s}$, a 5% increase in grain weight and dry matter accumulation were observed with mixed N nutrition. However, the physiological strategy used to achieve this increase varied as a function of genotype. For example, the hybrid LHE136 x LH82 increased the partitioning of dry matter to the grain, whereas LH74 x LH51 increased dry matter production when supplied with mixed N. Mixed N nutrition also increased whole shoot N content of all hybrids (range of 5 to 14%), because of greater efficiency of N uptake. In addition, mixed N nutrition decreased the magnitude of kernel abortion for the hybrid B73 x LH51, or increased the number of ovules per earshoot for the hybrid LH74 x LH82. The enhanced reproductive development observed under mixed N conditions may be related to the supply of cytokinin, a growth-regulating substance. Six applications of 22 $\\mu$M 6-benzylaminopurine (a cytokinin) to the developing shoot of plants supplied with NO$\\sb3\\sp-$ increased grain production to that of mixed N plants. In addition, the endogenous supply of cytokinin to the shoot was greater for mixed N plants during vegetative growth. Based on data from these studies, the enhanced yield observed under mixed N conditions appears to be related to genotypic differences in assimilate partitioning, kernel development, N accumulation, and cytokinin supply.","abstract_html":"Although the maize (Zea mays L.) plant can utilize either NH$\\sb4\\sp+$-N or NO$\\sb3\\sp-$-N, many studies have shown that mixed N nutrition (NH$\\sb4\\sp+$ + NO$\\sb3\\sp-$) can optimize productivity. However, the physiological processes that are beneficially altered by mixed N have not been elucidated. Therefore, studies were conducted to compare plant productivity traits under mixed N or predominantly NO$\\sb3\\sp-$ nutrition. Mixed N nutrition enhanced early season leaf area and leaf number, stimulated post-anthesis nitrate reductase activity, and lessened late-season chlorophyll degradation. Although NO$\\sb3\\sp-$-grown plants had equivalent or greater rates (approximately 5 to 10%) of canopy photosynthesis (P$\\sb{\\rm s}$) than mixed N plants, the duration of P$\\sb{\\rm s}$ was unaffected by N-form treatment at photosynthetic photon flux densities of 900, 1800 or mathematically integrated from 600 to 2100 <span class=\"etd-inline-math\">&mu;</span>mol photon m$\\sp{-2}$ s$\\sp{-1}$. Despite the lowered rates of P$\\sb{\\rm s}$, a 5% increase in grain weight and dry matter accumulation were observed with mixed N nutrition. However, the physiological strategy used to achieve this increase varied as a function of genotype. For example, the hybrid LHE136 x LH82 increased the partitioning of dry matter to the grain, whereas LH74 x LH51 increased dry matter production when supplied with mixed N. Mixed N nutrition also increased whole shoot N content of all hybrids (range of 5 to 14%), because of greater efficiency of N uptake. In addition, mixed N nutrition decreased the magnitude of kernel abortion for the hybrid B73 x LH51, or increased the number of ovules per earshoot for the hybrid LH74 x LH82. The enhanced reproductive development observed under mixed N conditions may be related to the supply of cytokinin, a growth-regulating substance. Six applications of 22 <span class=\"etd-inline-math\">&mu;</span>M 6-benzylaminopurine (a cytokinin) to the developing shoot of plants supplied with NO$\\sb3\\sp-$ increased grain production to that of mixed N plants. In addition, the endogenous supply of cytokinin to the shoot was greater for mixed N plants during vegetative growth. Based on data from these studies, the enhanced yield observed under mixed N conditions appears to be related to genotypic differences in assimilate partitioning, kernel development, N accumulation, and cytokinin supply.","abstract_has_math":true,"creators":["Smiciklas, Kenneth Donald"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Crop Sciences","degree_department":null,"school":null,"contributors":["Below, Frederick E."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T12:43:40Z","date_published":"2011-05-07T12:43:40Z","updated_at":"2026-07-22T22:25:16Z","subjects":["Agriculture, Agronomy","Biology, Plant Physiology"],"languages":["eng"],"rights":["Copyright 1991 Smiciklas, Kenneth Donald"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9136737","(UMI)AAI9136737"],"render_values":[{"text":"AAI9136737","href":null,"code":true},{"text":"(UMI)AAI9136737","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/20592","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Below, Frederick E."]},{"key":"dc:creator","label":"Author","values":["Smiciklas, Kenneth Donald"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T12:43:40Z","10000-01-01","1991"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Crop Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Agriculture, Agronomy","Biology, Plant Physiology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1991 Smiciklas, Kenneth Donald"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9136737","(UMI)AAI9136737","http://hdl.handle.net/2142/20592"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Although the maize (Zea mays L.) plant can utilize either NH$\\sb4\\sp+$-N or NO$\\sb3\\sp-$-N, many studies have shown that mixed N nutrition (NH$\\sb4\\sp+$ + NO$\\sb3\\sp-$) can optimize productivity. However, the physiological processes that are beneficially altered by mixed N have not been elucidated. Therefore, studies were conducted to compare plant productivity traits under mixed N or predominantly NO$\\sb3\\sp-$ nutrition. Mixed N nutrition enhanced early season leaf area and leaf number, stimulated post-anthesis nitrate reductase activity, and lessened late-season chlorophyll degradation. Although NO$\\sb3\\sp-$-grown plants had equivalent or greater rates (approximately 5 to 10%) of canopy photosynthesis (P$\\sb{\\rm s}$) than mixed N plants, the duration of P$\\sb{\\rm s}$ was unaffected by N-form treatment at photosynthetic photon flux densities of 900, 1800 or mathematically integrated from 600 to 2100 $\\mu$mol photon m$\\sp{-2}$ s$\\sp{-1}$. Despite the lowered rates of P$\\sb{\\rm s}$, a 5% increase in grain weight and dry matter accumulation were observed with mixed N nutrition. However, the physiological strategy used to achieve this increase varied as a function of genotype. For example, the hybrid LHE136 x LH82 increased the partitioning of dry matter to the grain, whereas LH74 x LH51 increased dry matter production when supplied with mixed N. Mixed N nutrition also increased whole shoot N content of all hybrids (range of 5 to 14%), because of greater efficiency of N uptake. In addition, mixed N nutrition decreased the magnitude of kernel abortion for the hybrid B73 x LH51, or increased the number of ovules per earshoot for the hybrid LH74 x LH82. The enhanced reproductive development observed under mixed N conditions may be related to the supply of cytokinin, a growth-regulating substance. Six applications of 22 $\\mu$M 6-benzylaminopurine (a cytokinin) to the developing shoot of plants supplied with NO$\\sb3\\sp-$ increased grain production to that of mixed N plants. In addition, the endogenous supply of cytokinin to the shoot was greater for mixed N plants during vegetative growth. Based on data from these studies, the enhanced yield observed under mixed N conditions appears to be related to genotypic differences in assimilate partitioning, kernel development, N accumulation, and cytokinin supply.","Made available in DSpace on 2011-05-07T12:43:40Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9136737.pdf: 4583573 bytes, checksum: 164e7d6aa924069bf4ed3ac90575ecce (MD5) Previous issue date: 1991","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:44:56Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:19:50-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"]},{"key":"dc:title","label":"Title","values":["Physiological role of mixed nitrogen nutrition in enhancing productivity of maize"]}]}],"canonical_facts":{"dc:contributor":["Below, Frederick E."],"dc:creator":["Smiciklas, Kenneth Donald"],"dc:date":["2011-05-07T12:43:40Z","10000-01-01","1991"],"dc:description":["Although the maize (Zea mays L.) plant can utilize either NH$\\sb4\\sp+$-N or NO$\\sb3\\sp-$-N, many studies have shown that mixed N nutrition (NH$\\sb4\\sp+$ + NO$\\sb3\\sp-$) can optimize productivity. However, the physiological processes that are beneficially altered by mixed N have not been elucidated. Therefore, studies were conducted to compare plant productivity traits under mixed N or predominantly NO$\\sb3\\sp-$ nutrition. Mixed N nutrition enhanced early season leaf area and leaf number, stimulated post-anthesis nitrate reductase activity, and lessened late-season chlorophyll degradation. Although NO$\\sb3\\sp-$-grown plants had equivalent or greater rates (approximately 5 to 10%) of canopy photosynthesis (P$\\sb{\\rm s}$) than mixed N plants, the duration of P$\\sb{\\rm s}$ was unaffected by N-form treatment at photosynthetic photon flux densities of 900, 1800 or mathematically integrated from 600 to 2100 $\\mu$mol photon m$\\sp{-2}$ s$\\sp{-1}$. Despite the lowered rates of P$\\sb{\\rm s}$, a 5% increase in grain weight and dry matter accumulation were observed with mixed N nutrition. However, the physiological strategy used to achieve this increase varied as a function of genotype. For example, the hybrid LHE136 x LH82 increased the partitioning of dry matter to the grain, whereas LH74 x LH51 increased dry matter production when supplied with mixed N. Mixed N nutrition also increased whole shoot N content of all hybrids (range of 5 to 14%), because of greater efficiency of N uptake. In addition, mixed N nutrition decreased the magnitude of kernel abortion for the hybrid B73 x LH51, or increased the number of ovules per earshoot for the hybrid LH74 x LH82. The enhanced reproductive development observed under mixed N conditions may be related to the supply of cytokinin, a growth-regulating substance. Six applications of 22 $\\mu$M 6-benzylaminopurine (a cytokinin) to the developing shoot of plants supplied with NO$\\sb3\\sp-$ increased grain production to that of mixed N plants. In addition, the endogenous supply of cytokinin to the shoot was greater for mixed N plants during vegetative growth. Based on data from these studies, the enhanced yield observed under mixed N conditions appears to be related to genotypic differences in assimilate partitioning, kernel development, N accumulation, and cytokinin supply.","Made available in DSpace on 2011-05-07T12:43:40Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9136737.pdf: 4583573 bytes, checksum: 164e7d6aa924069bf4ed3ac90575ecce (MD5) Previous issue date: 1991","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:44:56Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:19:50-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"],"dc:identifier":["AAI9136737","(UMI)AAI9136737","http://hdl.handle.net/2142/20592"],"dc:language":["eng"],"dc:rights":["Copyright 1991 Smiciklas, Kenneth Donald"],"dc:subject":["Agriculture, Agronomy","Biology, Plant Physiology"],"dc:title":["Physiological role of mixed nitrogen nutrition in enhancing productivity of maize"],"dc:type":["text"],"thesis:degree_discipline":["Crop Sciences"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:16Z"}