Dissertations / Theses: 'Internal nitrogen use efficiency'

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Gherli, Hussein. "Nitrogen use efficiency in Brassica napus." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/97639/.

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The aim of this project was to enhance our knowledge of how nitrogen is transported and utilised within Brassica napus through the use of proteomics, phenotyping and genetic mapping. It highlights the importance of looking at all possible plant tissues to determine the mechanisms underlying seven macronutrients (N, P, Mg, Ca, S and Na) and five micronutrients (B, Cu, Fe, Mn and Zn) accumulation, since differences were observed between different tissues. Significant amount of mineral elements were found to remain in both the stem and roots at harvest, which in turn, highlights the inefficient mechanisms applied by some plants in the way they redistribute and utilise minerals such as N, P, K and S. Large genotypic differences in minerals concentration was found between different accessions of B. napus, ranging from 1.48-fold for Ca in the bottom of the stem to 20-fold for Na in top of the stem at maturity. Genotypes were identified that differed significantly from one another in relation to mineral concentration in the stem and root at harvest or in both. Differences were observed in the parents of the TN mapping population allowing a QTL approach to be adopted. Complex network of relationships between minerals were observed within and between tissues, and found to be dependent on the tissue and the growth stage. The strongest significant positive correlations (0.91 > r >0.71) were between Ca/P, S/Ca and N/Ca in taproot, Ca/Mg in stem, and Mg/P and N/S in seed. A significant source of N is that stored within proteins. Several proteins were shown to be accumulated significantly in the top part of the plants especially in the senescing silique walls and the stem adjacent to them. Putative vegetative storage proteins, VSPs, were identified in these tissues and we have suggested that these could be associated with N remobilisation. Development of a screening methodology based on these proteins through which quantitative analysis could be performed on a proteomic based experiment has been successfully developed which will allow the identification of QTLs associated with the N remobilisation and utilisation in plants. These finding could assist plant breeders in developing varieties with enhanced mineral utilisation efficiency. Such developments will eventually lead to significant benefits both economically and socially worldwide as they should lead to increased abilities to enhance crop yields of oilseed rape while lowering the fertiliser requirements.

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Brown, Tabitha Therisa. "Variable rate nitrogen and seeding to improve nitrogen use efficiency." Thesis, Washington State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10043121.

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Increased nitrogen (N) fertilizer additions to modern agricultural cropping systems will be necessary to feed a growing world population. However, greater nitrogen use efficiency (NUE) is required if agroecosystems are to continue to provide certain ecosystem services (e.g., greenhouse gas emission reductions and water quality goals). The aim of this research was to investigate the role of variable rate N and seeding of winter wheat (Triticum aestivum) for optimizing yield-water-NUE relationships across heterogeneous landscapes. Field plot studies were conducted at the Cook Agronomy Farm (CAF) near Pullman, WA during the 2010, 2011 and 2012 winter wheat harvest years. A randomized complete block split plot N rate x seeding rate experiment with N fertilizer rate as main plot and seeding rate as subplot was employed across three landscape positions. Assessed were evidence of “haying-off”, depletion of available water resources, and the link between yield, protein, and NUE response to landscape by N fertilization rate by seeding rate treatment combinations. A performance classification was developed to evaluate wheat performance with regard to N utilization efficiency (Gw/Nt) and N uptake efficiency (Nt/Ns) components of the NUE.

Evidence of haying-off in winter wheat was medium to high for drier landscape positions, particularly during low precipitation years and likely occurs in these landscapes most years. Treatment impacts on NUE varied by year and landscape but overall NUE decreased by 14 to 22 kg grain yield per kg N supply as N rate increased from 0 to 160 kg N ha^-1 across three landscape positions and two site years (2011 and 2012). Target NUE and maximum anthesis biomass could be achieved with a 34 to 68% reduction in typical seeding rates. The NUE-based performance classification was helpful in identifying environmental or management conditions contributing to low or high NUE indicating potential to be used as an evaluation tool. This research also included a policy fellowship focused on N₂O emission reductions and greenhouse gas offset credits that could be generated from adoption of variable rate N for wheat and concluded that offset credits alone would not provide enough incentive for adoption of variable rate N.

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Ransom, Curtis J. "Nitrogen Use Efficiency of Polymer-Coated Urea." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/3985.

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Plants require N to complete their life cycle. Without adequate concentration of N, crops will not produce their potential yields. For turfgrass systems, N fertilizer application allows for the maintenance of functional, aesthetic, and recreational properties. However, fertilizer mismanagement is common and leads to N pollution in the environment. Controlled-release and slow-release fertilizers can enhance nitrogen (N)-use efficiency, reduce N pollution, minimize the need for repeated fertilizer applications, and reduce turfgrass shoot growth and associated costs. In order to evaluate the effectiveness of these fertilizers in the Intermountain West, research is needed. The timing of N release was evaluated for seven urea fertilizers: uncoated, sulfur coated (SCU), polymer-sulfur coated (PSCU), and four polymer-coated (PCU) with release timings of 45, 75, 120, and 180 d estimated release. These products were placed on bare soil, a Kentucky bluegrass (Poa pratensis L.) thatch layer, and incorporated into soil. These three placement treatments were replicated to allow for enough samples to be placed in two locations. The first was outside in a field to represent field conditions with diurnal fluctuating temperatures and the second was placed in a storage facility to replicate laboratory conditions with static diurnal temperatures. The PCU prills incorporated into soil under field conditions generally released N over the estimated release period. However, when applied to bare soil or thatch, N from PCU had 80% or greater N release by 35 d after application regardless of expected release time. Fertilizers under laboratory conditions had minimal N release despite having similar average daily temperatures, suggesting that fluctuating temperatures impact N release. The PSCU and SCU treatments were no different from uncoated urea, showing no slow release properties for this particular product. Spring-applied N fertilizer trials were conducted over two years to determine the optimal N rate for Kentucky bluegrass. Similar PCU120 products were applied at 50, 75, and 100% of the recommended full rate, while also being compared to an unfertilized control and urea applied either all at once or split monthly. Spring-applied PCU showed minimal initial N response while urea applied all at once resulted in an initial spike of N uptake. Once PCU began to release N, there was minimal difference for all rates compared to urea split monthly for biomass growth, verdure, and shoot tissue N. Although at the 50% rate, there were a few sampling dates with slower growth and lower verdure. The decrease in verdure at this low rate was slight, and it is recommended that PCU could be applied effectively at a reduced rate between 50 and 75%. Although for better results, additional quick release N is required to compensate for early season lag in N release.

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Ahrens, Toby D. "Improving regional nitrogen use efficiency : opportunities and constraints /." May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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Thennakoon, Mudiyanselage Sakura Dilhani Karunarathne. "Genetic improvement of nitrogen use efficiency in barley." Thesis, Thennakoon Mudiyanselage, Sakura Dilhani Karunarathne (2021) Genetic improvement of nitrogen use efficiency in barley. PhD thesis, Murdoch University, 2021. https://researchrepository.murdoch.edu.au/id/eprint/64211/.

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Grain yield is the key target in barley production. A powerful tool to increase yield has been the use of fertilizers of which nitrogen (N) is the main nutrient for the productivity and grain quality. Yet excessive application leads to environmental pollution and high production costs. Therefore, improvement of nitrogen use efficiency (NUE) is fundamental for sustainable agriculture. Only limited research has been conducted on barley NUE. A few QTLs controlling NUE have been identified, albeit they are not stable across experiments due to low marker density, limited genetic diversity and small population size. Thus, the aims of this project are to investigate the barley tolerance to low-N, propose a candidate gene pool related to NUE and to develop advanced barley materials with improved NUE through CRISPR/Cas9 genome editing. Hydroponic screening of barley was conducted under low-N for 7 NUE related traits to identify low to moderate NUE commercial cultivars such as Compass with potential for further NUE improvement. 66 significant marker trait associations (MTAs) associated with NUE were identified through a genome wide association study (GWAS) using 282 barley accessions which is a subset of a larger worldwide barley panel. Key genes retrieved from the GWAS mainly belonged to nitrate transporters, asparagine synthetase gene family, several transcription factor families and protein kinases. High-affinity nitrate transporter 2.7 (HvNRT2.7) and a chloroplast envelope membrane protein (HvARE1) on chromosome 7H, protein NRT1/PTR FAMILY 8.3 (HvNRT1) gene on 4H and asparagine synthetase 2 (glutamine hydrolyzing) (HvASN2) on 1H were identified as promising loci for NUE improvement under low-N. In addition, a part of this research proposes the use of chlorate ions as an analogue to nitrate for rapid and large scale NUE screening of barley using a multiparent advanced generation inter-cross (MAGIC) population developed from four commercial barley cultivars Compass, GrangeR, LaTrobe and Lockyer. An independent GWAS identified 9 MTAs and a candidate gene pool with D2H71173319_GA, D2H655480684_ CT and D3H37942201_CT repeatedly identified in both experiments under low-N. MTA4H546806926_TC which exhibits concordance with high NUE phenotype can further be explored under different genetic backgrounds and successfully applied in marker-assisted selection (MAS). CRISPR/Cas9 gene editing of the HvARE1 gene successfully generated 22 potential mutant lines from barley cv. Golden Promise. Transformation efficiency was 87% based on the Cas9 and CaMV35S promoter specific PCR detection. 18% of T1 and 24% of T2 individuals were mutants based on PCR-RE assay. Missense and frameshift mutations were identified by Sanger sequencing from both T1 and T2 generations. Interestingly, the are1 mutants had a 1.5 to 2.8-fold increase of the chlorophyl content at the grain filling stage and a delayed leaf senescence than that of the wild type. Overall, the are1 mutants had better performance in terms of agronomic and physiological traits related to NUE under both low and optimal N. The results of this research can be successfully adopted to improve commercial barley cultivars for high NUE and yield through CRISPR/Cas9 gene editing.

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Kakkar, Avneet. "Nitrogen Availability and Use Efficiency in Corn Treated with Contrasting Nitrogen Sources." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6886.

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The plant-soil nitrogen cycle plays a significant role in allocation of available N to plants, and improved understanding of N cycling helps sustainably increase fertilizer use efficiency. There are various processes (nitrogen mineralization and nitrification) involved in the availability and mobility of nitrogen in the soil. The primary objective of this study was to determine the NUE under contrasting nitrogen treatments over a period of five years. Additionally, we examined the effect of different N treatments on N mineralization and nitrification in conventional and organic farming systems. This project was funded by Agriculture and Food Research Initiative Competitive Grants Program Grant no. 2011-67019-30178 from the USDA National Institute of Food and Agriculture and by the Utah Agricultural Experiment Station. We established silage corn field plots in northern Utah, and silage corn was grown using ammonium fertilizers or manure composts over five years. Nitrogen use efficiency was found to be higher in ammonium sulfate fertilizer treatments as compared to compost treated soils. Nitrogen mineralization and nitrification rates were examined for soils from the silage corn field plots and also for additional soils from certified organic field plots receiving steer compost, steer manure and crop rotations. There was a significant overall nitrogen treatment effect for both conventional and organic rotational plots. Carbon mineralization rates were found to be higher in compost under conventional plots and manure under organic rotational plots as compared to control. There was no significant treatment effect found in gross mineralization and nitrification rates in 2015 and 2016. Gross nitrification rates were found to be the higher in AS200 treatment versus compost and control in 2016. Improved knowledge of the timing and rates of nitrogen supply is vital for improving NUE and for reducing excessive use of fertilizers while maintaining an acceptable yield. The optimization of fertilizer rates according to crop demand at different stages of growth will be helpful in the efficient management of available N especially for composts and manures.

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Zhao, Yun. "Genetic dissection of wheat nitrogen use efficiency related traits." Thesis, Zhao, Yun (2019) Genetic dissection of wheat nitrogen use efficiency related traits. PhD thesis, Murdoch University, 2019. https://researchrepository.murdoch.edu.au/id/eprint/57397/.

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Nitrogen is not only an essential element for wheat development, but also a major determinant for wheat yield and protein quality. It is vital to improve wheat nitrogen use efficiency (NUE) as nitrogen is the most important component of all fertilizers that are provided for the pursuit of a higher wheat yield and better protein quality. Wheat NUE is an important quantitative trait that is very complex and easily influenced by the environment and its controlling network is still not clear. In the current study, a wheat doubled haploid (DH) population was used to study the genetic variations of NUE and its controlling mechanism in wheat. Through quantitative genetic locus (QTL) mapping method, a suite of QTLs associated with NUE related traits as well as yield and yield component traits under different nitrogen rates and different environmental conditions were obtained. For yield components, results showed major QTLs for seed number per main spike (SN) were located on 3A and 5A, the SN QTL on 3A was detected in three environments and explained 32.16% of phenotypic variation. QTLs for thousand kernel weight (TKW) were detected on 2A, 2D, 4A, 4B, 5A, 6A and 7D. The most significant TKW QTL was located at 123 cM on 2A, with LOD and PVE of 16.93 and 20.35%, respectively. Major QTL for grain weight (GW) was located on 5A, with LOD and PVE of 4.42 and 13.26%, respectively. Important QTLs related to grain protein content (GPC) were identified on 1B, 2D, 4B and 5A, GPC QTL on 5A was the most significant, with logarithm of odds (LOD) and phenotypic variation explained (PVE) of 11.36 and 17.04%, respectively. Important NUE related QTLs identified in this study were QTL for Straw protein content (SPC) on 3B, QTL for nitrogen Harvest index (NHI) on 1B, 2B, 5A and 6B. QTL for nitrogen utilization efficiency for grain yield (NUtE) on 1B, 3A and 6B. Besides the large numbers of QTLs identified related to each trait investigated in this study, several chromosome regions were identified to be associated with multiple traits and were detected in multiple environments, including a QTL cluster located at 131 cM at 1B, associated with GPC, SPC and NUtE; QTL cluster located at 111-115 cM on 3A associated with TKW, SN and NUtE; QTL cluster located at 153-155 cM on 4B associated with kernel traits and GPC. Compared with other QTLs that were only detected in single environment, these QTL regions deserve more attention. Metabolites profiling of over 1000 metabolites in mature wheat kernels were carried out to facilitate the candidate gene identification for those regions and other important traits. Because of the causal relationships between metabolites and their closely correlated traits, metabolites identified to be colocalized with these genetic regions will assist further narrowing down these regions harbouring the underlying candidate genes. A single gene controlled major QTL for stem diameter that is positively correlated with grain yield was located on Chromosome 3BL. A list of candidate genes was generated from search of wheat reference map using the flanking markers of this QTL. TaCOMT gene was suggested as one of the candidate genes for stem diameter, further confirmation of the genetic function work is needed. Many modern commercial wheat cultivars contain 1B.1R translocation due to its high yield and disease resistance characteristics despite its negative impact on breadmaking quality caused by the Sec-1 locus on rye 1R chromosome. Wheat gliadins are important parts of wheat storage proteins that determine the extensibility of wheat gluten, which is crucial for breadmaking. In the current study, the gliadin constituent dynamics across the population were studied via reverse phase high-performance liquid chromatography (RP-HPLC) and size exclusion high-performance liquid chromatography (SE-HPLC) to reveal the 1B.1R impacts on seed gliadin compositions. The two parental lines differ in 1B.1R genotype and with High molecular weight glutenin subunits (HMW-GS) composition, ie., 2*, 17+18, 2+12, vs 2*, 7+9, 5+10. Results from SE-HPLC indicated that lines with 1B.1R translocation showed significantly lower SDS-unextractable polymeric protein (UPP) percentage, Ratio of polymeric proteins to monomeric proteins (P/M) and Ratio of glutenin proteins to gliadin proteins (Glu/Gli). However, this undesirable effect was significantly alleviated by HMW-GS 17+18 in one growing environments. The population RP-HPLC profiles could be clearly distinguished into two groups, with lines containing 1B.1R showed more individual proteins originated from the rye translocation. To elucidate the genetic mechanism behind the chromatograph pattern, QTL-mapping analysis was carried out to detect the underlying genetic factors controlling the gliadin components and the results indicated that some gliadin fractions were controlled by gene loci other than the Sec-1 locus. This study provided new insights into maintaining a balanced grain yield and quality through utilising the 1B.1R translocation line in wheat breeding.

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Hitz, Katlyn. "Breeding for Nitrogen Use Efficiency in Soft Red Winter Wheat." UKnowledge, 2015. http://uknowledge.uky.edu/pss_etds/62.

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Nitrogen use efficient (NUE) wheat varieties have potential to reduce input costs for growers, limit N runoff into water ways, and increase wheat adaptability to warmer environments. Previous studies have done little to explain the genetic basis for NUE and components, nitrogen uptake efficiency (NUpE) and nitrogen utilization efficiency (NUtE). Four studies were conducted to 1) determine genotypic stability of NUE under high and low N regimes and under warming 2) determine effect of warming on NUE 3) indentify QTL associated with NUE components 4) assess the utility of canopy spectral reflectance (CSR) as a high-throughput phenotyping device for NUE. Genotypic response to N stress or warming varied. Uptake efficiency was found to be more important than utilization efficiency to genotypic performance under high and low N environments and under warming. Selection under low N for NUpE and under high N for NUtE most efficiently identified NUE varieties. Uptake and utilization were lower under warming due to quickened development. No strong correlations between the CSR indices and NUE existed. No QTL were found to be significantly associated with NUE components. Further research into the mechanisms controlling NUE and to reveal plant response to N stress and under warming is necessary.

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Ogola, J. B. Ochanda. "Improving water use efficiency of maize through proper nitrogen management." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340024.

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Stadler, Christina. "Nitrogen release and nitrogen use efficiency of plant derived nitrogen fertilisers in organic horticultural soils under glasshouse conditions." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980532159.

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Nett, Leif. "N use efficiency in field vegetable production systems." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://dx.doi.org/10.18452/16463.

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In der vorliegenden Studie wurden zwei Fragestellungen bearbeitet, die beide das Ziel verfolgen, die Stickstoff(N)-Ausnutzungseffizienz in landwirtschaftlichen Systemen zu steigern: 1) Hat die langjährige organische Düngung einen Einfluss auf den Abbau kürzlich applizierter organischer Dünger? Die Hypothese war, dass relevante Effekte nur bei schwer abbaubaren organischen Düngern auftreten während bei leicht abbaubaren organischen Düngern die Düngungshistorie keine Rolle spielt. 2) Können die hohen N-Bilanzüberschüsse im intensiven Freilandgemüsebau durch den Einsatz von Winterzwischenfrüchten (ZF) deutlich reduziert werden? Die Hypothese war, dass ZF die Bilanzüberschüsse der betrachteten zweijährigen Fruchtfolgen um mindestens 30 kg N / ha reduzieren. Die erste Hypothese wurde überprüft, indem der Abbau organischer Dünger in Böden, die sich in ihrer organischen Düngungshistorie unterschieden, gemessen wurde. Es wurden ein Topfversuch im Gewächshaus sowie ein Inkubationsversuch im Labor durchgeführt. Die Ergebnisse deuteten darauf hin, dass es Effekte der Historie auf den Abbau von Stallmist und Kiefernrinde gab, während es keine Effekte bei leicht abbaubarem Kohlmaterial gab. Daher wurde die Hypothese angenommen. Allerdings ergaben die beobachteten Effekte kein konsistentes Bild in Hinblick auf die Richtung der Effekte auf die Kohlenstoff(C)- und N-Mineralisierung und Effekte auf die Netto-N-Mineralisation waren generell sehr klein. Zur Überprüfung der zweiten Hypothese wurden an drei Standorten in Deutschland Feldversuche mit Gemüsefruchtfolgen und unterschiedlichen ZF durchgeführt. Die Ergebnisse ergaben, dass trotz der die mittleren Bilanzüberschüsse der Kontrollen (ohne ZF) von 217 kg N / ha die ZF die N-Bilanz im Mittel um nur 13 kg N / ha reduzierten. Daher wurde die Hypothese abgelehnt. Die Ergebnisse zeigten weiterhin, dass der verlustfreie Transfer der von der ZF aufgenommenen N-Menge an die Folgefrucht ein kritischer Schritt bei dieser Technik ist.
The current study dealt with two questions that target potential options to increase the nitrogen (N) use efficiency of agricultural systems: 1) Does long-term organic fertilization affect the decomposition of recently added organic fertilizers? The hypothesis was that effects only occur for recalcitrant organic fertilizers while for readily decomposable organic fertilizers, the fertilization history does not play a role. 2) Can the N balance surpluses in intensive field vegetable production systems be substantially reduced by cultivation of winter catch crops (CC)? The hypothesis was that the N balance surpluses of the investigated two-year crop rotations can be reduced by more than 30 kg N / ha. The first hypothesis was tested by applying organic fertilizers to soils that only differed in organic fertilization history. A greenhouse pot experiment and a laboratory incubation experiment were conducted. The results indicated that fertilization history had effects on the decomposition of farmyard manure and pine bark, not however on the decomposition of readily decomposable cabbage material. Hence, the hypothesis was accepted in that fertilization history effects depended on the type of fertilizer. However, fertilization history effects showed no consistent trend with respect to increase or decrease in carbon (C) and N mineralization and the effects on net N mineralization were minor in magnitude. The second hypothesis was tested by performing field experiments at three sites in Germany. Vegetable crop rotations were set up, testing different types of CC. The results suggested that in spite of high N surpluses in the control treatments (no CC) of 217 kg N / ha, CC reduced the N balance surplus on average by only 13 kg N / ha. Hence, the hypothesis was rejected. The findings further indicated that the transfer of N taken up by the CC to the succeeding crop is a critical step when adopting this technique.

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Kage, Henning. "Simulation modelling for improving nitrogen use efficiency in intensive cropping systems." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=977957020.

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Al-Habbar, Zaid. "Improve Nitrogen use efficiency of wheat cultivars under Western Australian conditions." Thesis, Al-Habbar, Zaid (2018) Improve Nitrogen use efficiency of wheat cultivars under Western Australian conditions. PhD thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/53212/.

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Nitrogen use efficiency (NUE) of wheat cultivars can be improved by modifying the onset of senescence to optimise sink-source balance for target environments. The NUE can be divided into two main components: nitrogen uptake efficiency (NUpE), shows the capacity of the plant to absorb N from the soil; and nitrogen utilisation efficiency (NUtE), shows the ability to use available N within plant to produce grain. Therefore, understanding the mechanism regulating NUE and its components is required to produce high yielding cultivars with minimum N application. The objective of this study was to investigate the impact of No Apical Meristem gene (NAM) on the senescence in relation to NUE in Australian wheat cultivars. An additional aim was to identify the critical traits associated with NUE and its components under low and high N conditions. Nineteen cultivars of bread wheat (Triticum aestivum L.) carrying different combination of NAM gene were studied under three levels of N fertilisation applied at two development stages in two-year field trials at Western Australia. Further detailed investigation was carried out through two glasshouse experiments using four cultivars with significant differences in nutrient remobilisation, which were selected based on the results of field trials with different N treatments. In general, NUE showed stronger association with NUpE rather than NUtE. The traits correlated to high NUE include, greater above-ground biomass, robust root system and stay-green attribute to increase pre-anthesis N uptake and post-anthesis N remobilisation. Cultivars carrying functional allele of NAM-B1 or/and NAM-A1a allele accelerated the onset of senescence, while the non-functional allele of NAM-B1 or/and NAM-A1c and d alleles delayed the onset of senescence. The complete absence of the functional NAM-B1 gene is a common phenomenon in Australian wheat cultivars. However, NAM-A1, a gene with a similar function to NAM-B1 involved in remobilising nutrients and accelerating senescence, is characteristic of Australian cultivars. Accelerating the onset of senescence results in a short grain filling phase reaching to mature grain before the unfavourable summer conditions with dry season end and promote better remobilisation of stored carbon and nitrogen at Western Australia conditions. As concluded, NUE could be improved by selecting specific combinations of NAM gene alleles for target environments by fine-tuning the duration of growth phases influencing the sink-source relationships. Furthermore, selecting genotypes with high NUE require identifying the key traits under low nitrogen conditions, as well as, under high nitrogen conditions.

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Dorsey, Nathaniel D. "Nitrogen use efficiency and nitrogen response of wheat varieties commonly grown in the Great Plains, USA." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/17618.

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Master of Science
Department of Agronomy
Nathan O. Nelson
Increasing nitrogen use efficiency (NUE) and nitrogen response in winter wheat could help producers reduce input costs associated with nitrogen fertilizers and decrease the negative environmental impacts of N loss. The objectives of this research were to i) establish if there are genetic differences in NUE and other related parameters among wheat varieties commonly grown in the Great Plains, ii) determine if there are differences in N response among select varieties with a range of NUEs, and iii) determine if NUE influences N response. This information could be useful in future breeding efforts as researchers seek to develop more efficient varieties. This was approached by conducting two separate studies, a large NUE study with 25 winter wheat varieties, and a smaller N Rate study with 4 varieties that represented a range of NUEs based on the preliminary results of the NUE study. The NUE study was conducted over the course of several seasons and locations, with treatments of consisting of N Rate and variety. The experiment was laid out in a strip-plot design and replicated four times at each location. In the 2010-11 and 2011-12 seasons it was planted at the Kansas River Valley Experiment Field in Rossville, KS. In the 2012-13 season the experiment was planted at two locations, one at Silverlake and another at Ashland Bottoms, KS. The experiment was again planted at two locations in the fall of 2013, in Ashland Bottoms, KS, and Hutchinson, KS. The wheat varieties were grown with two N rates, 0 kg N ha⁻¹ and 90 kg N ha⁻¹. Nitrogen use efficiency was calculated as the grain yield per unit of available nitrogen (sum of soil N and fertilizer N) and ranged from 22-30 kg of grain per kg of N and was strongly influenced by variety with a p<0.001. Several other related parameters, such as grain yield, nitrogen utilization efficiency, harvest index, and fertilizer use efficiency were also significantly affected by variety with a p<0.05. These data suggest there are significant genetic differences in how varieties use and transport nitrogen within their tissues to produce grain. The N Rate experiment was planted in two locations during the 2012-13 season at Silverlake and Ashland Bottoms, KS, and planted again in the fall of 2013 at Ashland Bottoms and Hutchinson, KS. This experiment was laid out in a split-plot design with four varieties and four nitrogen rates. The varieties selected for this study were Duster, Everest, Jagger, and Larned and the four N rates were 0, 33.6, 89.7, and 145.7 kg N ha⁻¹. The results showed significant differences in yield response among the varieties at only one location, Ashland Bottoms (p=0041). Although N response at Silverlake was not significant, mean grain yields between varieties was significant (p<0.001). Two additional parameters, NUE and harvest index (HI), were also significantly different between varieties at Silverlake, KS with a p<0.05, while no additional parameters were significant at Ashland Bottoms. Those varieties that had higher response, Everest and Jagger, also tended to have higher NUEs compared to the other two varieties, Duster and Larned. However, because of the contrasting results between locations, additional research is needed to develop firm conclusions. These results provide significant evidence to support varietal differences in nitrogen use due to genetics, and provide the opportunity for breeders to begin developing varieties with higher NUE and improved N response. However, additional research will be required to determine the specific traits responsible for these varietal differences and to determine the suitability of high NUE crops for meeting the nutritional requirements of the future.

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Zhang, Chenxi. "Nitrate Uptake of Kentucky Bluegrass as a Determinant of Nitrogen Use Efficiency." Thesis, North Carolina State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3538535.

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Nitrate (NO₃^-) leaching from fertilized land can be detrimental to aquatic ecosystems and human health. Although NO₃^- leaching potential is generally found to be low in turfgrass, certain conditions can occur that result in increased leaching loss of nitrogen. Kentucky bluegrass (Poa pratensis L.) is the most widely used cool-season turfgrass species in the temperate and subarctic climate zones in the United States. Due to its popularity, many new cultivars are bred and released each year. Despite the ample amount of information characterizing the agronomic features of Kentucky bluegrass genotypes, little is available documenting their physiological characteristics related to nitrogen use efficiency and how these might affect the NO₃^- leaching potential of the genotypes. Such information would be of great value for both scientists and customers.

In this comprehensive study, a screening procedure was developed using nutrient solution culture to evaluate differences in NO₃^- uptake among sixty Kentucky bluegrass genotypes. Two cultivars were selected from the sixty to represent genotypes having high vs. low capacity for NO₃^- uptake. These two cultivars were then used to examine the relationship between NO₃^- uptake efficiency and competitiveness for soil nitrogen. Finally, these two cultivars were compared to determine if NO₃^- uptake efficiency affected NO₃^- leaching potential.

There were significant differences in NO₃^- uptake at both high (1 mM) and low (0.05 mM) N concentrations among sixty Kentucky bluegrass genotypes, with a strong correlation between uptake rates at high and low N concentrations. Julia and Midnight were selected as representing cultivars with efficient and inefficient nitrate uptake, respectively. In nutrient solution culture, Julia exhibited 56% higher NO₃^- uptake rates than Midnight. In a root competition study, in which the root systems of the two cultivars occupied the same soil volume, Julia was more competitive for nitrogen acquisition (absorbed 20 to 71% more NO₃^- ) than Midnight. However, the higher NO₃^- uptake capacity and better competitiveness for soil N in Julia did not result in lower NO₃^- leaching potential. These results suggest that differences in root morphology and architecture may play a more important role than uptake capacity in determining nitrate leaching potential among Kentucky bluegrass genotypes.

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Munyinda, Kalaluka. "Efficiency of water and nitrogen use by wheat and legumes in Zambia." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75446.

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Maximum wheat (Triticum aestivum L.) yields in Zambia were obtained with weekly irrigation at 85% of class A pan evaporation during the whole irrigation interval and split application of urea N of which the initial portion of the fertilizer was either broadcast and incorporated or broadcast after the crop had established itself. This corresponded with maximum utilization of fertilizer N. The proportion of N derived from fertilizer was independent of fertilizer placement at various water regimes and N utilization was primarily a function of water availability.
Two nonnodulating soybean (Glycine max L.) cultivars, Clark RJ1 and N77, or in their absence Pearl millet (Panicum glaucum L.) were judged to be appropriate reference crops for estimating N$ sb2$ fixation by soybeans using $ sp{15}{ rm N}$ isotope dilution techniques. A local soybean cultivar, Magoye, was rated highest among three cultivars tested for its ability to support N$ sb2$ fixation by Bradyrhizobium japonicum and contributed biologically fixed N$ sb2$ to a subsequent wheat crop.

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Kindred, Daniel R. "Investigating heterosis for yield, breadmaking quality and nitrogen use efficiency in wheat." Thesis, University of Reading, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412168.

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Irving, Louis John. "Genetic and environmental controls of nitrogen use efficiency in barley ('Hordeum vulgare')." Thesis, University of Aberdeen, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415531.

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The aim of this thesis was to explore the physiological basis for differential yield characteristics of a barley QTL mapping population. In 2002, 1.1 million tonnes of inorganic N fertiliser was applied in the UK, most of it to cereal crops. Economic considerations aside, reduction of fertiliser applications, whilst maintaining yield, is a desirable goal, as a nitrogen, especially as nitrate, can be leached from the soil, causing environmental damage. 5.6 million tonnes of barley was grown in the UK during 2002. Barley requires less fertiliser-N than wheat, much of which is recovered in biomass at harvest; however significant quantities of N are lost from the system. Initial pot-based trails of the QTL mapping population parental lines suggested phenotypic plasticity in their response to N application. This was followed up by a further three experimental studies investigating the role of the chloroplast enzyme, Rubisco, in N storage, and its importance in the plants N economy. Rubisco comprises approximately 25-30% of leaf N, or 15 - 20% of total plant N. Rubisco is also important in the plants C metabolism, catalysing the Calvin cycle reaction between ribulose-1,5-bisphosphate and carbon dioxide, and represents the sole plant of inorganic carbon entry into biological systems. Field and laboratory-based trials were conducted to explore the hypothesis that Rubisco protein turnover is a mechanism of plant N loss, and that the regulation of turnover would have an impact on plant yield and grain properties. Results suggest that barley genotypes exhibit a range of Rubisco turnover rates, and this affects not only the efficiency with which N is stored in the plant, but also the photosynthetic capacity of the plants, which correlates, ultimately, with yield.

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Fernando, K. M. C. "Exploration of favourable traits for nitrogen use efficiency in ancient wheat species." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/31015/.

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Nitrogen (N) fertiliser is one of the main inputs of intensive wheat cropping systems in the UK. The average application of N fertiliser in the UK for winter wheat was 220 kg N ha-1 in 2011, but typically only 50% of this applied N is taken up by the crop. Breeding crops for high N use efficiency (NUE; grain dry matter yield per unit availability of N from soil and/or fertiliser) while maintaining acceptable yield, is widely accepted as one of the approaches to maximise farmers’ revenue and minimise pollution risk by reducing N fertiliser application. NUE is divided into two components; N uptake efficiency (NUpE; crop N uptake per unit availability of N from soil and/or fertiliser) and N utilisation efficiency (NUtE; grain dry matter yield per crop N uptake). NUE can be improved by improving NUpE and /or NUtE. Targeted integration of favourable traits into breeding programmes needs adequate diversity of the existing genotypes. However, genetic diversity of modern bread wheat is narrowed due to chance hybridisation events during wheat evolution and selective breeding for high yield. Hence, it has become necessary to search for novel sources of genetic variation for NUE. One of the sources could be the ancient wheat species, which provide novel resources of genes to improve NUE of modern bread wheat. The overall objective of the current project is to explore favourable physiological traits for NUE in ancient wheat species. Three field experiments, four glasshouse experiments and three growth room experiments were conducted at Sutton Bonington Campus, University of Nottingham. The current work can be divided into four main components; (i) investigation of general plant growth and development, (ii) quantification of NUE and its components, (iii) exploration of root architectural traits of seedlings and mature plants, and (iv) identification of seedling root QTLs related to NUpE in a wheat x spelt population. Significant variation for plant establishment and development was identified among wheat species where bread wheat had high plant establishment and faster plant development compared to ancient wheat species. Above ground biomass production of bread wheat, spelt and emmer was either similar or bread wheat was slightly higher at maturity under high N levels (HN). However, high above ground biomass production at zero N (no N fertiliser; NN) was observed in spelt genotypes. High grain yield of bread wheat is due to improved harvest index when compared to tall ancient wheat species. Delayed onset of flag leaf senescence, slow senescence rate and prolonged leaf greenness were observed in some spelt genotypes, especially spelt cv. Oberkulmer and were positively associated with biomass production. Flag leaf length, width, green area, specific leaf area and SPAD values were significantly different between genotypes used in the study. The greatest green area, SPAD value and maximum width were recorded in bread wheat. NUE was higher in bread wheat followed by spelt, emmer and einkorn. Emmer 2 had higher NUpE than spelt, bread wheat and einkorn genotypes. Delayed senescence hence extended green area duration and deep and vigorous root system might have influenced NUpE of spelt genotypes. High fertiliser N recovery rate of emmer 2 may be associated with well distributed, shallow, horizontally grown root system, especially at early plant growth. NUtE of bread wheat is higher than ancient wheat species and closely related to harvest index and reduced plant height. NUtE is more controlled by genetic factors than NUpE. N supply has a negative relationship with NUpE and its components. Relationships between NUE and its components were not consistent between experiments in the study. However, NUpE and NUtE explained more of the variation in NUE under HN than NN. Root system architecture varied significantly between wheat species used in the study. Seminal root characters of the seedling such as tip angle, number of seminal roots, seminal root length and total root length are closely related to mature root systems. Spelt had long seminal roots with narrow tip angles and hence develops deep root system while having a well-developed superficial root system due to nodal roots. Therefore, both top soil scavenging and deep soil foraging occurs efficiently. A large and deep root system contributes significantly to greater above-ground biomass and green area production of spelt. A greater number of seminal roots with wide tip angles help emmer to develop a root system architecture well adapted to take up fertiliser N from the top soil layers, especially in early stage of the plant growth. There is a possibility of using seedling root traits such as total root length and average length of the seminal root to predict NUpE at maturity. Therefore, these traits might be used as selection criteria for crop breeding for efficient N uptake. Emmer had favourable seedling root traits related to NUpE while spelt showed more favourable root traits at for N uptake at maturity than modern bread wheat and einkorn. Root N uptake efficiency and specific absorption rate of N were higher in emmer than spelt, bread wheat and einkorn. Phenotypic evaluation and genetic analysis of recombinant inbred lines (RILs) produced from the cross between Swiss winter wheat variety Forno (Triticum aestivum) and Swiss winter spelt cv. Oberkulmer (T. spelta) was carried out. Two parents of the population were significantly different for a number of traits, including: number of seminal roots, average length of seminal roots, total root length, maximum width, width to depth ratio, tip angle and emergence angle of seminal root. All measured root traits of seedlings of the RILs varied significantly. A total of 26 significant QTLs were identified for seedling root traits. These QTLs were located on ten different chromosomes; 1BS, 2A, 2D, 3A, 3B, 4A, 5A, 5B, 7AL and 7D. QTL coincidence was found for total root length either with number of seminal roots or seminal root length of the seedlings which showed strong phenotypic relationship. RILs F5-10, F5-36, F5-134, F5 146, F5-230 and F5-234 could be efficient genotypes for N uptake at maturity. The contribution of the A genome to the phenotypic variation observed within this cross for the development of the seedling root system is more important than the B and D genomes, as assessed by QTL analysis. Further studies are needed to identify QTLs associated with NUpE and root architectural traits of emmer and spelt. Favourable root traits in emmer and spelt related to NUpE could be introduced to bread wheat through direct crossing or creating synthetic wheat. The introgression of spelt into modern bread wheat will be useful for molecular studies to develop marker assisted breeding for high NUpE.

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Acharya, Tej Prasad. "Water Requirements, Use Efficiency, and Insect Infestation in Brussels Sprouts, and Nitrogen Use Efficiency in Sweet Basil under Low Tunnels compared to Open-field Production." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/86610.

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Sustainable vegetable production is one of the most active areas of vegetable research and of concern to all producers. Everyone, both producers and consumers, are concerned with sustainability. Brussels sprouts and sweet basil are high value commodities, but increasing global concerns about water availability, insect-pest problems, and costly fertilizer inputs severely impact the growth and production of these crops. Low tunnels covered with spun-bonded fabric can improve production of vegetables and herbs in Virginia and the U.S. This study investigated the performance of Brussels sprouts and basil grown under low tunnels (LTs), and their relationship with water use efficiency, nitrogen use efficiency, and the level of protection against insect injury. Low tunnels increased yield, number of sprouts, and water use efficiency of Brussels sprout production. In addition, LTs decreased irrigation requirements, irrigation events, leaf feeding injury, and insect populations in comparison to open field. Similarly, LTs increased summer production of sweet basil as measured by fresh weight and biomass. In addition, plant N uptake was greater under the LTs; however, the increase in nitrogen use efficiency was inconsistent.
Master of Science in Life Sciences
Brussels sprouts and sweet basil are economically important cash crops on the East Coast. Brussels sprouts is a Cole crop and an important source of dietary fiber, vitamins (A, C & K), calcium, iron, manganese and antioxidants. Similarly, sweet basil is a member of the mint family and important high-value herb in the U.S. and the world. It is mainly grown for culinary purposes as a dried and fresh spice in the U.S. However, demand for these commodities is increasing. Low tunnels (LTs) covered with spunbonded fabric can be a practical management tool to increase yield. Results from this study indicate that LTs increase yield of Brussels sprouts and basil, water use efficiency and total nitrogen uptake, while reducing insect pest infestation. Therefore, LTs can be a useful tool to improve sustainability of Brussels sprouts and basil production.

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Mahama, George Yakubu. "Variation among grain sorghum genotypes in response to nitrogen fertilizer." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/13580.

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Master of Science
Department of Agronomy
P.V. Vara Prasad
Grain sorghum [Sorghum bicolor (L.) Moench] is an important crop in the semi-arid regions of Africa, Asia and United States. Productivity of grain sorghum is limited by soil fertility, especially nitrogen (N). Sorghum genotypes are known to vary in their response to nitrogen, however, the information on nitrogen use efficiency (NUE) is limited. The objectives of this research were to (a) determine the response of sorghum genotypes (hybrids and inbred lines) to nitrogen fertilizer (b) quantify genotypic differences in NUE; and (c) determine physiological and morphological basis of NUE. Field experiments were conducted at three locations in Kansas (Hays, Ottawa and Manhattan) during 2010 and 2011. Six hybrids and six inbred lines of grain sorghum were grown with 0, 45 and 90 kg N ha-1.The experimental design was a split-plot design with N regimes as main plots and genotypes as sub-plot, with four replications. Planting was done in May and June across all the locations, and nitrogen fertilizer (Urea, 46% N) was applied at emergence. Data on N concentration in the leaves, stems and grain were determined. NUE and components of N use were computed for Ottawa and Manhattan as follows: Nitrogen use efficiency (NUE): Grain weight / N supplied; Nitrogen utilization efficiency: Grain weight / N total in plant; Nitrogen uptake efficiency: N total in plant / N supplied; Percent fertilizer recovery = [uptake (fertilized plot) – N uptake (un- fertilized plot)] / [ N applied ] x 100; and Nitrogen harvest index (NHI) = Grain N / N total in plant. Where N supplied = Rate of N fertilizer applied + soil N supplied. Growth and yield data were collected at all locations. There were significant effects of genotypes (P < 0.05) and nitrogen (P < 0.05) on biomass and grain yield across all locations. Performance of hybrids was generally superior to the inbred lines of all traits. Sorghum hybrids 26506 and 99480 produced maximum grain yield across all locations. While inbred lines B35 and SC35 had the lowest grain yield. Maximum biomass and grain yield was obtained at 90 kg N ha-1, followed 45 kg N ha-1, and lowest in 0 N kg ha-1. There were significant differences among genotypes for all NUE traits at Ottawa and Manhattan. Across genotypes, total NUE ranged from 17.2 to 42.6 kg kg-1, utilization efficiency from 24.3 to 60.2 kg kg-1, N uptake efficiency ranged from 56.1 to 82.5%, recovery from 2 to 52%, and NHI from 43.6 to 81.3%. Among the genotypes, 99480 and 26506 both known to be post–flowering drought tolerance were high in NUE and component of N use. While genotypes B35 and SC35 were the lowest in NUE and components of N use. Overall, our data suggest that there were significant differences for NUE traits in sorghum hybrids and inbred lines. There are opportunities to breed for higher NUE in grain sorghum.

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Okeno, James Aketch. "Genetic and physiological studies of yield and nitrogen use efficiency in spring barley /." Göttingen : Cuvillier, 1999. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=008638432&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

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23

Miro, Berta. "Identification of traits for nitrogen use efficiency in oilseed rape (Brassica Napus L.)." Thesis, University of Newcastle Upon Tyne, 2010. http://hdl.handle.net/10443/1067.

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Oilseed rape (Brassica napus L.) receives high inputs of Nitrogen (N) fertiliser while N uptake and N harvest index are low. This results in high residual soil N which leaches to water bodies and contributes to greenhouse emissions. Such negative environmental impact could be reduced by better understanding the genetic basis of N metabolism in oilseed rape and designating relevant traits for varietal selection towards high nitrogen use efficiency (NUE) at low N fertiliser inputs. In this study the doubled haploid population (TNDH) from a cross between the Chinese semi-winter variety Ningyou7 and the UK winter variety Tapidor was analysed for N physiology and Quantitative Trait Locus (QTL) mapped for relevant traits. Quantitative Trait Loci were mapped in two N treatments over two consecutive field trials for architectural traits such as plant height, foot length, pod number and chlorophyll content in bracts and leaves; yield and yield component traits such as plant biomass, seed yield, harvest index and N metabolism (seed, plant and total N concentration, N uptake, utilisation and use efficiencies and N harvest index). A larger number of QTL were detected at High N than at Low N. In total 49 QTL were detected at High N versus 44 in Low N during 2005/06, while in 2007/07, 72 versus 62 QTL were detected at High and Low N respectively. Most QTL for different traits were treatment specific. Novel QTL for agronomic traits specific at Low N were identified. The correlations between traits were also studied through QTL co-localisations, particularly for relationships between seed yield, N uptake and N use efficiency. Seven chromosomal regions are discussed for potential candidate genes. Additionally, QTL reproducibility, interval mapping and composite interval mapping, QTL x environment interactions and phenotypic plasticity in oilseed rape are also discussed.

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Silva, Adilson Nunes da. "Nitrogen impacts on maize yield and nutrient use efficiency in contrasting stress environments." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-22042015-153310/.

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Nitrogen (N) fertilization and drought stress have large influence on maize grain yield, thus studies about genotypes and management technologies are very important to increase maize production. This study is presented in three chapters; the first two were undertaken in the United States of America and the third one in Brazil. The following objectives are addressed in this order: (1) The primary objective was to understand which traits, if any, differ between similar-maturity tolerant and non-drought tolerant hybrids that govern nutrient uptake and concentrations under different management treatments (varied plant densities (PD) and N rates) and their influence on grain yield (GY). (2) The primary objective was to investigate the physiological and yield responses of comparable-maturity drought and non-drought tolerant hybrids (P1151 vs. P1162, and P1498 vs. 33D49) to varied plant density and N rates. (3) The main objective was to investigate the responses of maize to sidedress N applications, using isotopically labeled urea fertilizer (15N), at different development stages. The secondary objective was to verify the correlations between the chlorophylls and carotenoids with SPAD index (evaluated at V14 and V16) and all these parameters with total biomass (BM), harvest index (HI), GY and grain N content. The major results for objectives 1 and 2 were as follows: All hybrids had similar GY responses to PD (near 79,000 versus near 100,000 plants ha-1) and N rate (from 0 to 269 kg N ha-1) treatment factors. Hybrid 1 (AQUAmax(TM) P1151) demonstrated similar leaf photosynthetic (A) and transpiration (E ) rates than its non-drought tolerant counterpart of similar maturity since Hybrid 2 (P1162) had a higher leaf area Index (LAI) (at the R2 and R3 stages) and a similar GY as Hybrid 1. Hybrid AQUAmax(TM) P1498 maintained higher leaf A and E rates than P33D49 during the grain-fill period, thus perhaps demonstrating improved persistence in root water uptake late in the season. There was no single trait differentiation in photosynthesis or transpiration between drought and non-drought tolerant hybrids. Highest BM and GY at maturity generally followed shorter anthesis-silking intervals and more stover macronutrient (P and S) accumulation, in the drought season, so these characteristics appeared to be important drought-tolerant mechanisms regardless of hybrid designations. The major findings from the objective 3 investigations: Maize crop responded similarly for GY to timing of sidedress N application. Grain N content from 15N fertilizer and N uptake and efficiency were greater for early N applications. SPAD values correlated positively with most pigment variables at V16 in both seasons, thus proving that SPAD was an efficient instrument of indirect evaluation of chlorophylls and carotenoids in maize leaves at early stages. Chlorophyll b at V16, sample stage, was positively correlated (P<0.05) with grain N content, GY, and BM, and total chlorophyll at V16 was positively correlated with GY and grain N content. However the chlorophylls a and total, evaluated at V14, were negatively correlated with GY. So, measurement chlorophyll and carotenoid pigment contents should be done after V14 stage when studies aim to evaluate crop nutritional conditions and prescribe future grain production practices.
Adubação nitrogenada (N) e o estresse hídrico tem grande influência no rendimento de grãos de milho, assim, estudos sobre genótipos e o manejo dessa cultura são muito importantes para o aumento da produtividade. Este estudo é apresentado em três capítulos. Os dois primeiros foram desenvolvidos nos Estados Unidos e o terceiro no Brasil. Os objetivos são apresentados na seguinte ordem: (1) o objetivo principal foi entender quais características, se existirem, diferem entre híbridos tolerantes e não-tolerantes à seca, com semelhança em maturidade, que regem a absorção de nutrientes e concentrações destes sob diferentes tratamentos de cultivo e sua influência na produção de grãos. (2) O objetivo principal foi investigar as respostas fisiológicas (fotossíntese (A) e transpiração (E)) e a produção de milho em genótipos, com semelhante maturidade, tolerantes e não tolerantes ao déficit hídrico (P1151 vs. P1162 e P1498 vs. 33D49) em relação a variação de densidade de plantas e doses de N. (3) O principal objetivo foi investigar as respostas de milho à aplicação de nitrogênio em cobertura, ureia fertilizante (15N), em diferentes estádios fenológicos. O objetivo secundário foi: verificar a correlação entre as clorofilas e carotenoides com SPAD (avaliado em V14 e V16) e destas com a biomassa total (BM), índice de colheita (IC), produção de grãos (PG) e do conteúdo de N nos grãos. Como resultados: (1 e 2) Todos os híbridos responderam de forma semelhante para para PG em relação aos tratamentos. O Híbrido P1151 demonstrou semelhantes A e E e menor area foliar do que seu semelhante em maturidade (P1162). Híbrido P1498 pareceu ser capaz de manter a taxa de transpiração foliar e de fotossíntese mais elevadas do que 33D49, durante o período de enchimento de grãos. Este híbrido apresentou uma melhor persistência na captação de água pela raiz no final da estação de cultivo. Geralmente maiores BM e PG na maturidade foram relacionadas a menores intervalos de diferenciação floral e a maior acumulação, na estação seca, de macronutrientes (P e S) no colmo, sendo as ultimas características consideradas como mecanismos de tolerância à seca. (3) A cultura do milho respondeu de forma semelhante em relação a PG à aplicação de N. O teor de nitrogênio nos grãos derivado do 15N fertilizante e a eficiência de uso do fertilizante nitrogenado foram maiores em relação a aplicação de N nos primeiros estádios. Houve correlação positiva e siginificativa para SPAD com a maioria dos pigmentos no estádio de avaliação V16. Provando ser um instrumento eficaz de avaliação indireta de clorofilas e carotenóides em estágios iniciais. A clorofila b, avaliada em V16, apresentou correlação positiva significativa (p<0,05) com teor de N nos grãos, PG, e BM, a clorofila total em V16 também apresentou uma correlação positiva com o teor de N nos grãos, no entanto, as clorofilas a e total, avaliadas em V14, apresentaram correlação negativa com PG. Assim, a medição do teor de pigmentos com o objetivo de estudar as condições nutricionais e previr a produção de grãos deve ser realizada após o estágio V14.

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Mundim, Gabriel Borges. "Genetic diversity, path analysis and association mapping for nitrogen use efficiency in popcorn." Universidade Federal de Viçosa, 2013. http://locus.ufv.br/handle/123456789/4780.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Os objetivos deste estudo foram (i) identificar linhagens de milho-pipoca eficientes no uso de nitrogênio; (ii) avaliar a diversidade genética entre linhagens de milhopipoca em alto e baixo N; (iii) investigar os efeitos causais de vários caracteres sobre a eficiência no uso de nitrogênio (NUE) e (iv) identificar marcadores SSR associados com caracteres relacionados à NUE. Foram avaliadas 25 linhagens-elite de milhopipoca pertencentes às populações 'Viçosa' e 'Beija-Flor', em alto e baixo N. Foram mensurados os seguintes caracteres: crescimento diário (DG, cm), massa de parte aérea (SDW, mg), de raiz (RDW, mg), e da planta total seca (TDW, mg), razão parte aérea:raiz seca (RSR), eficiência no uso (NUE, mg mg-¹), na absorção (NUpE, mg mg-¹) e na utilização (NUtE, mg mg-¹) de nitrogênio, diâmetro médio (RAD, mm), comprimento total (TRL, cm), área superficial (RSA, cm²) e volume (RV, cm³) de raízes. Foram identificadas linhagens eficientes em cada nível de N. A avaliação da diversidade genética pelo método de agrupamento UPGMA baseado no quadrado da Distância Euclidiana Média resultou em quatro grupos de linhagens para cada nível de N e a análise de componentes principais mostrou que as linhagens poderiam ser agrupadas predominantemente pelos seus caracteres de parte aérea. A eficiência na absorção de N (NUpE) foi a característica mais importante para a NUE em estádios precoces de desenvolvimento da planta em ambos os níveis de N, por apresentar alta correlação e alto efeito direto sobre a variável principal (NUE) na análise de trilha. Em baixo N, a eficiência na utilização de N (NUtE) também apresentou alta correlação e alto efeito direto sobre a variável NUE, mostrando ser uma característica importante para esta condição nesses estádios. Contudo, a seleção direta ainda parece ser o melhor método para aumentar a eficiência de seleção para NUE em estádios precoces. Três marcadores SSR foram validados como associados com os caracteres relacionados à NUE pela análise de mapeamento associativo baseada em ANOVA.
The objectives of this study were to (i) identify efficient inbred lines in nitrogen use; (ii) assess the genetic diversity among popcorn inbred lines under high and low N; (iii) investigate the causal effects of several traits in nitrogen use efficiency (NUE) and (iv) identify SSR markers associated with the traits related to NUE. Twenty-five elite popcorn inbred lines belonging to the 'Viçosa' and 'Beija-Flor' populations were evaluated under high and low N. The following traits were assessed: daily growth (DG, cm), shoot dry weight (SDW, mg), root dry weight (RDW, mg), total plant dry weight (TDW, mg), root:shoot ratio (RSR), nitrogen use efficiency (NUE, mg mg-¹), nitrogen uptake efficiency (NUpE, mg mg-¹), nitrogen utilization efficiency (NUtE, mg mg-¹), root average diameter (RAD, mm), total root length (TRL, cm), root surface area (RSA, cm²) and root volume (RV, cm³). Efficient inbred lines were identified under each N level. The genetic diversity assessment using the UPGMA method based on the squared Mean Euclidean distance grouped the inbred lines into four clusters for each N level and the principal component analysis revealed that the inbred lines could be categorized predominantly by their shoot traits. Nitrogen uptake efficiency (NUpE) was the most important trait for NUE in the early stages of plant development under both N levels, due its high correlation with and high direct effect on NUE obtained in the path analysis. Under low N, nitrogen utilization efficiency (NUtE) also showed high correlation with and direct effect on NUE, demonstrating its importance in this N level in these early stages. Notwithstanding, the direct selection still seems to be the best method to increase the selection efficiency for NUE in these early stages. Furthermore, three SSR markers were identified as true associations with the traits related to NUE, through the association mapping analysis based on ANOVA.

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26

Bonyadi, Pour Roxanna. "Nitrogen use efficiency in plants : how roots and nodules are balanced in Medicago." Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/73274/.

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Nitrogen availability is central to global food security. Understanding how plants respond to nitrogen could help develop crops with improved nitrogen use. This study aims to investigate how lateral root (LR) and nodule development are balanced in response to low (0.1 mM) and high (5 mM) NH4NO3 concentrations in the model legume Medicago truncatula var. Jemalong A17 using phenotypic and gene regulatory network analysis. High concentrations of NH4NO3 have an inhibitory effect on nodulation. The phenotypic measurements of root architecture of A17 in response to NH4NO3 and rhizobia showed that at high NH4NO3 rhizobia affected LR development. Total root size was less (P < 0.05) in rhizobia inoculated samples compared to the absence of rhizobia. This was due to a shorter primary root and less number of LRs. Whole genome profiling of early (2 and 6 hour) root responses to high NH4NO3 and rhizobia identified 4793 genes that were differentially expressed (significance cutoff of P<0.05). The early (2 and 6 h) responses to high NH4NO3 were mainly independent of the rhizobia effect and N-induction especially at 2 h time point was the predominant response. Some of the components of the autoregulation of nodulation (AON) pathway are also involved in LR development. The sunn-1 mutant is impaired in correct AON signals that lead to hypernodulation with short LRs at low N. Whole genome expression analysis of A17 and sunn-1 root samples identified 7186 significantly (P<0.05) expressed genes showing rhizobia and/or SUNN-regulated responses. These genes could be components of the AON pathway with putative role in balancing the number of nodules with LR development. Using motif analysis tools we identified motifs with putative promoters that were mainly Nodule specific cysteine rich peptides (NCRs). We suggest that these NCRs may be involved in regulating LR and nodule development depending on the plant N status.

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Brasier, Kyle Geoffrey. "Physiological Traits and Quantitative Trait Loci Associated with Nitrogen Use Efficiency in Soft Red Winter Wheat." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/89216.

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Development of winter wheat (Triticum aestivum L.) cultivars capable of more efficient uptake and utilization of applied nitrogen (N) has the potential to increase grower profitability and reduce negative environmental consequences associated with N lost from the plant-soil system. The first study sought to evaluate genotypic variation for N use efficiency (NUE) and identify lines consistently expressing high or low NUE under two or more N rates in a total of 51 N-environments. The results indicated that significant genotype by N rate interactions were frequently observed when trials utilized at least three N rates and identified wheat lines with high and stable yield potential that varied in performance under low N conditions. In addition, NUE was associated with above-ground biomass at physiological maturity were found to be both highly heritable across multiple N supplies. In the second study, two bi-parental mapping populations having a common low ('Yorktown') and two high (VA05W-151 and VA09W-52) NUE parents were characterized to dissect the genetics underlying N response. The populations were evaluated in eight N-environments and genotyped using single-nucleotide polymorphism data derived from a genotyping-by-sequencing protocol to identify quantitative trait loci (QTL) associated with high NUE. Six QTL for NUE were identified on chromosomes 1D, 2D, 4A, 6A, 7A, and 7D that were associated with N use efficiency. The QTL on 2D and 4A co-localized with known loci governing photoperiod sensitivity and resistance to Fusarium head blight (caused by the fungal pathogen Fusarium graminearum Schwabe), respectively. Three of the identified QTL (6A, 7A, and 7D) were associated with NUE in previous investigations, while the QTL on 1D was novel. The final experiment employed a small panel of soft red winter wheat lines to study the effects of photoperiod alleles on chromosome 1D (Ppd-D1) on yield-related traits under three or five N rates that were variably split over two growth stages in eight environments. The results validated the effect of a photoperiod sensitive allele (Ppd-D1b) that was associated with increased grain yield across N rates in half of the Virginia testing environments and under low N rates in all Ohio testing sites at the expense of grain N content. Yield advantages conferred by the Ppd-D1b allele were attributable to increased floret fertility and kernel number per spike. The findings from these studies have direct application for winter wheat breeding programs targeting NUE improvements.
Doctor of Philosophy
Wheat (Triticum aestivum L.) products account for a significant percentage of the total dietary calories and protein consumed globally. To meet production demands, wheat requires efficient nitrogen (N) management to ensure continued grower profitability and to reduce negative environmental impacts of N lost from agricultural systems. This dissertation sought to evaluate variation among wheat lines for N use efficiency (NUE), assess the performance of wheat lines under multiple N supplies, validate traits that are associated with NUE, investigate the role of photoperiod sensitivity genes on N response, and identify regions of the wheat genome associated with high N use efficiency. These studies were conducted using panels of winter wheat lines grown under two or more N conditions over a combined 32 location-years. Results of Chapter I identified variation in cultivar response to N rates was more frequently observed when a greater number of N rates were used in trials of wheat N response. The first chapter also identified variation among wheat lines for NUE and identified lines that consistently produce high grain yields over N-location-years. In addition, above-ground biomass at physiological maturity was found to be strongly associated with grain yield under all N rates and was highly heritable in both studies. Chapter II utilized a combination of genetic and observable trait data to perform genetic analysis in two bi-parental populations grown in eight Nlocation-years. The study identified reproducible and significant genetic markers associated with NUE for application in wheat breeding programs. Upon analysis of photoperiod sensitive versus insensitive wheat lines in Chapter III, photoperiod sensitive wheat lines had a significant yield advantage under N-limited conditions in Ohio and across N treatments in half of the Virginia testing location-years. This resulted from an increased number of kernels per spike and fertile florets in photoperiod sensitive wheat lines. Results from this dissertation suggest that active breeding and selection for N response may be achieved through the employment of high NUE genes and the continued identification of adapted high NUE wheat parental lines.

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Tateno, Ryunosuke. "Nitrogen use efficiency of trees in relation to the relative availability of soil nitrogen to light along forest structure." Kyoto University, 2003. http://hdl.handle.net/2433/148995.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第10270号
農博第1342号
新制||農||868(附属図書館)
学位論文||H15||N3791(農学部図書室)
UT51-2003-H691
京都大学大学院農学研究科地域環境科学専攻
(主査)教授武田博清, 教授東順一, 教授谷誠
学位規則第4条第1項該当

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Theobald, Julian C. "The effect of elevated CO2 on nitrogen allocation between components of the photosynthetic machinery in Spring wheat." Thesis, Open University, 2000. http://oro.open.ac.uk/58084/.

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Wheat (Triticum aestivum L. cv Minaret) was grown long-term under CO₂ partial pressures of 36 and 70 or 100 Pa with various N applications (4 to 23 g m-2 N), to test hypotheses of N re-allocation: 1) a decrease in N from leaves to other organs, 2) a relative decrease in N from Rubisco to other photosynthetic components. Elevated CO₂ did not affect phenology, main stem leaf appearance, the pattern of N allocation throughout the plant, or the fraction of crop N in grain at harvest, but 1) stimulated biomass and yield by 5 to 20% over the N range used, and 2) caused a faster loss of N and components from flag leaves during grain-fill. Responses of photosynthesis to varying pCi were fitted, and rates of maximal carboxylation and non-photorespiratory respiration estimated. The former, was proportional to Rubisco content, and light-saturated photosynthetic rate at 70 Pa CO₂ was proportional to A TP-synthase. Potential photosynthetic rates at 70 Pa CO₂ were calculated, compared with observed, and used to estimate excess investment in Rubisco. The excess was greater in high N treatments than low, declining as leaves senesced. The fraction of Rubisco estimated to be in excess, was strongly dependent on leaf N content, increasing from - 5% in leaves with 1 g N m-2 to -40% in leaves with 2 g N m-2. Growth at elevated CO₂ usually decreased the excess somewhat, but only as a consequence of a general decrease in leaf N, given that relationships of components to leaf N content were independent of CO₂ and N treatment, demonstrating that no direct CO₂ effect on N allocation within leaves had occurred. It is concluded that there is scope for improving the N-use efficiency of C₃ crop plants in elevated CO₂ conditions, by genetic manipulation to decrease the amount of Rubisco.

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Pointeau, Virginie M. "Water-use efficiency and productivity in native Canadian populations of Populus trichocarpa and Populus balsamifera." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/587.

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Afforestation and reforestation programs utilizing available fields for biofuel production, carbon sequestration, and other uses linked to climate change are looking to tree physiologists to identify species and genotypes best-suited to their purposes. The ideal poplar genotype for use in Canadian programs would be drought-resistant, cold-climate adapted, and fast-growing, thus requiring an understanding of links between a variety of physiological traits linked to growth and productivity. This study examined the basis for variations in water-use efficiency within four selected populations of Populus trichocarpa and Populus balsamifera (2 provenances each). Each species included both a northern and a southern provenance. Correlations between water-use efficiency, nitrogen-use efficiency, ¹³C/¹²C isotope ratio, stomatal conductance, and overall productivity were evaluated. Gas exchange variables measured included net photosynthesis, transpiration rate, stomatal conductance, and intercellular CO₂ content. Water-use efficiency and ¹³C content across all genotypes were highly correlated. Results suggested that variation in water-use efficiency was primarily related to variation in stomatal conductance across all genotypes. Whereas differences in net photosynthesis in this study were not significant between species, P. balsamifera did reveal a higher average stem volume overall. Although variation in stomatal conductance was the major determinant of differences in water-use efficiency, positive correlations were found between ¹³C isotope abundance and net photosynthesis in both P. balsamifera provenances. In this regard, results for the northern P. balsamifera provenance are the most consistent across all gas-exchange and growth trait correlations, in terms of meeting expectations for sink-driven water-use efficiency. The findings in this study suggest the possibility of identifying poplar genotypes with an absence of trade-off between water-use efficiency and nitrogen-use efficiency, notably among genotypes from the northern P. balsamifera provenance, near Gillam.

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Singh, Ajay. "Water and nitrogen use efficiency of corn (Zea mays L.) under water table management." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116989.

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Drainage and water table management are essential for crop production in humid regions. Water table management not only increases crop yield, but also reduces nitrate leaching to water bodies. This study investigated the water and nitrogen use efficiency of corn under two water management conditions and three nitrogen fertilizer levels. The sap flow heat balance method was used to measure the daily water uptake of corn, over an extended period of the growing season. The impacts of climate change on grain corn and biomass yield in eastern Canada under tile drained conditions was also evaluated over a 30 year future period (2040 to 2069). The study was conducted at a field scale in 2008 and 2009 at St. Emmanuel, Quebec. The two water management conditions were: conventional drainage (FD), and controlled drainage with subirrigation (CD-SI). The three nitrogen (N) fertilizer treatments (low, medium, and high N) were applied in a strip across three blocks. The seasonal water balance indicated that the plants in the CD-SI plots had more water than required in the wet periods, despite the system automation, while the FD plots exhibited deficit water conditions. Water could be saved in the wet periods by better regulating water supplied by subirrigation. However, in dry years, the CD-SI system increased yield. The grain corn water use efficiency (WUE) for FD plots was 2.49 and 2.46 kg m-3, in 2008 and 2009, respectively. In these years, the grain WUE for CD-SI plots was 2.43 and 2.26 kg m-3. Water management treatments demonstrated significant difference (p < 0.05) in grain yields in 2009, at low and high nitrogen levels. However, at the medium nitrogen level, water management demonstrated no significant effect (p > 0.05) on grain yields. The two water treatments had no effect on the above-ground dry biomass yields in both years. Mean nitrogen use efficiency (NUE) of grain corn and biomass varied from 27 to 99 kg kg-1. Highest NUE (99 kg kg-1) was observed under low N (~120 kg N ha-1) and lowest NUE (41 kg kg-1) occurred in the high N (~260 kg N ha-1). This might be due to higher nitrogen losses due to leaching, residual nitrogen in the soil, and more denitrification in high N plots. The rate of plant water uptake measured by the sap flow method, varied from 3.55 to 5.11 mm d-1 from silking to full dent stage of corn growth. These rates were consistent with ETc calculated by the FAO-56 Penman-Monteith method (3.70 to 5.93 mm d-1) for both years. Although, silking is considered as a critical stage for corn growth, water demand was highest at the milk stage (45.63 to 59.80 mm). Transpiration during this stage constituted 10 to12% of the total water requirement of the corn for the season. The silking to full dent stage accounted for approximately 40% of the total water requirement of the crop. The STICS (JavaStics v1.0) crop model was used to examine the impacts of climate change, under the B1 emissions scenario, on corn yield from 2040-2069. The model was calibrated using 2008 field measured data, and then validated using the 2009 data set. Corn grain yield was underestimated by 1.5 to 2.6 Mg ha-1 for the two years of measurement. Total dry biomass was also underestimated by 0.9 to 2.6 Mg ha-1. Simulations for the B1 emissions scenario using synthetic weather data was run under the same crop conditions as in 2008. Tukey's studentized range (HSD) test of corn grain yield indicated that yields at high and low N, and high and medium N were different at the 95% confidence level. Grain and biomass production from 2040-2069 under B1 emissions scenario responded differently (p < 0.05) for the three N treatments. However, the Mann–Kendall test showed neither increasing nor decreasing trend (MK-stat > - 1.96) at a 95% confidence level.
Le drainage et la gestion de la nappe phréatique des parcelles agricoles permet non seulement d'augmenter la production des récoltes, mais aussi de réduire les pertes de nitrates par lessivage, qui contribue à leurs transferts vers les étendues d'eau. Cette étude a examiné l'efficacité d'utilisation de l'eau et de l'azote du maïs grain sous deux conditions de gestion de l'eau et trois niveaux d'application d'azote. Les facteurs climatiques jouent un rôle important dans la production du maïs-grain. Les impacts des changements climatiques sur les projections de maïs-grain et de la production de biomasse en sol drainé ont aussi été évalués pour l'est du Canada pour une période futur de 30 ans (2040 à 2069). L'étude a été accomplie à l'échelle du champ en 2008 et en 2009 à Saint Emmanuel au Québec. Les deux scénarios de gestion de l'eau étaient (a) le drainage conventionnel (FD) et (b) le drainage contrôlé combiné à l'irrigation souterraine (CD-SI). Les trois traitements d'azote (N) (dose faible, moyenne et élevée) ont été appliqués en bande sur trois blocs. L'efficacité d'utilisation de l'eau du maïs (WUE) pour les blocs en FD était de 2.49 kg m-3 et 2.46 kg m-3 en 2008 et 2009 respectivement. Pour ces années, L'WUE du maïs-grain pour les blocs en CD-SI était de 2.43 kg m-3 et de 2.26 kg m-3. Les traitements relatifs à la gestion de l'eau ont permis d'améliorer la production de rendement du maïs-grain significativement (p <0.05) en 2009, que cela soit avec des doses d'azotes basses ou élevées. Cependant, pour des doses intermédiaires, la gestion de l'eau n'a démontré aucun effet significatif (p> 0.05) sur les productions de maïs-grain. Les deux traitements relatifs à la gestion de l'eau n'ont eu aucun effet sur la production de biomasse sèche au-dessus du sol pour les deux années. L'efficacité moyenne de l'utilisation de l'azote (NUE) du maïs grain et de sa biomasse variait de 27 kg kg-1 à 99 kg kg-1. La plus haute NUE (99 kg kg-1) a été observée pour une dose de N faible (~120 kg N ha-1). La plus basse NUE (41 kg kg-1) s'est produite pour une dose de N élevée (~260 kg N ha-1). La consommation des plantes en eau mesurée par la méthode d'écoulement de la sève, vari de 3.55 mm d-1 à 5.11 mm d-1 pour la période de l'apparition des soies jusqu'à la croissance complète du maïs-grain. Ces taux sont en accord avec l'ETc calculée (3.70 mm d-1 à 5.93 mm d-1) pour les deux ans. Bien que, le développement de la soie soit considéré comme le stade critique pour le maïs-grain, la demande en eau fut la plus élevée lors du stade laiteux du développement du maïs (45.63 mm à 59.80 mm). À ce stade, 10 à 12% des besoins totaux de la plante en eau pour la saison furent transpirés. Du stade de la soie jusqu'au développement complet de l'épi de maïs les besoins en eau de la plante ont représenté environ 40 % de son besoin total. Le modèle de récolte STICS (JavaStics v1.0) a été utilisé pour examiner les effets du changement climatique sur la production de maïs- grain, de 2040 à 2069 et sous le scénario d'émissions de gaz à effet de serre B1. Le modèle a d'abord été calibré en utilisant les données mesurées au champ en 2008 et, a ensuite été validé avec l'ensemble des données de 2009. La production de maïs-grain est sous-estimée de 1.5 Mg ha-1 à 2.6 Mg ha-1 pour les deux ans de mesure. La biomasse sèche totale est aussi sous-estimée de 0.9 Mg ha-1 à 2.6 Mg ha-1. Les simulations pour le scénario d'émissions B1 en utilisant des données météorologiques synthétiques font été utilisées dans les mêmes conditions de récolte que 2008. Les prédictions de la production de maïs-grain et de sa biomasse pour la période 2040-2069 sous le scénario d'émissions B1 sont différentes (p <0.05) selon les trois traitements de N. Cependant, l'épreuve de Mann-Kendall n'a montré aucune tendance à la hausse ou à la baisse (MK-stat> - 1.96) pour un niveau de confiance de 95%.

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Cormier, Fabien. "Nitrogen use efficiency inwheat in bread wheat (T. aestivum L.) : breeding & gene discovery." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22574/document.

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Dans un contexte de réduction des intrants agricoles, la création de variétés de blé qui utilisent l’azote de manière plus efficiente est aujourd’hui nécessaire. Cette thèse, issue d'un partenariat public-privé entre l'Institut National de la Recherche Agronomique et Biogemma, avait pour but d'apporter des outils nécessaires à la création de variétés répondant à cette exigence. Pour ce faire, nous avons analysé 225 variétés commerciales génotypées avec 24K SNP et testées dans huit combinaisons d’année, lieu et régime azoté. Nous avons montré que même si la sélection a amélioré l’efficience d’utilisation de l’azote en condition optimale et sub-optimale, ce progrès génétique doit être accéléré et mieux réparti entre les différents traits. Nous proposons pour cela de mixer sélection phénotypique et sélection assistée par marqueurs. Dans ce sens, nous avons développé une méthode pour définir les régions chromosomiques associées à nos 28 traits. Parmi les 333 régions identifiées, nous avons notamment localisé le gène NAM-A1 et avons pu caractériser ses variants naturels. Nous avons aussi montré que la sélection génomique pourrait être plus efficace si les SNP étaient présélectionnés en fonction de leurs significativités en génétique d’association multi-environnementale. Les réseaux d’interactions épistatiques furent aussi étudiés, mettant en évidence un sous-réseau particulièrement intéressant. Nos résultats et méthodes sont discutés au regard des stratégies d’amélioration variétale et de découverte de gènes. Des pistes de recherche complémentaires et des améliorations ont aussi été suggérées
In a context of fertiliser reduction, breeding for enhanced nitrogen use efficiency in bread wheat is necessary. This PhD thesis resulting from private-public collaboration between the French National Institute for Agricultural Research and Biogemma aimed providing necessary tools. Analyses were conducted using a dataset of 225 commercial varieties genotyped with 24K SNP and tested in eight combinations of year, location, and nitrogen regimes. We showed that even if past selection increased nitrogen use efficiency at high and moderate nitrogen regimes, genetic progresses need to be accelerated and better balanced between traits. This could be achieved by mixing phenotypic and marker assisted selections. In this sense, we developed a method to define quantitative trait locus from genome-wide association study: 333 chromosomal regions involved in 28 NUE-related traits have been identified. The NAM-A1 gene was located in one of these regions and its natural variants were characterized. We also showed that genomic selection could be improved by pre-selecting SNP based on their significance in a multi-environmental genome-wide association study. Networks of epistasis interactions were also studied and an interesting sub-network was identified. Results and methods are discussed regarding breeding and gene discovery strategy. Further investigations and improvements are suggested

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Viktor, Aleysia. "Physiological and metabolic factors determining nitrogen use efficiency of tomato seedlings grown with elevated dissolved inorganic carbon and different nitrogen sources." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52999.

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Thesis (MSc)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: The aim of this study was to determine (l) the influence of elevated dissolved inorganic carbon (DIC) on the nitrogen use efficiencies (NUE) of tomato seedlings grown with different nitrogen sources, (2) how changes in the regulation and activities of nitrate reductase (NR), phosphoenolpyruvate carboxylase (PEPc), carbonic anhydrase (CA) and subsequent changes in metabolites would account for observed changes in NUE, and (3) to what extent elevated DIC contributed to the carbon budget of plants grown with different nitrogen sources. Lycopersicon esculentum cv. Fl44 seedlings were grown in hydroponic culture (pH 5.8) with 2 mM of either N03- or NH4 + and the solutions were aerated with either 0 ppm or 5000 ppm CO2 concentrations. The similar NUEs of NH/-fed plants grown with either root-zone CO2 concentration were largely due to their similar RGRs and N uptake rates. Elevated root-zone DIC had an initial stimulatory effect on N~ + uptake rates, but it seems as if this effect of DIC physiological processes was cancelled out by the toxic effect of unassimilated NH/. The NUE for N03--fed plants supplied with 5000 ppm root-zone CO2 was higher relative to 0 ppm root-zone CO2 and it was possibly due to the higher relative growth rates for similar N uptake rates of 5000 ppm compared to 0 ppm root-zone CO2. Nitrate-fed plants grown with 5000 ppm compared to 0 ppm root-zone CO2 had higher in vivo NR and in vitro NR and PEPc activities. These increases in enzymes activities possibly lead to increases in organic acid synthesis, which could have been used for biomass accumulation. This would account for the increased relative growth rates of N03--fed plants grown with 5000 ppm compared to 0 ppm root-zone CO2. The increasing rootzone CO2 concentrations resulted in the Ó15N values of NH/-plants becoming more positive indicating an absence of enzymatic discrimination. This may have been due to the inhibitory effect of DIC on Nll,+ uptake, causing plants to utilise both internal isotopes equally. The Ól3C studies showed that PEPc contributed equally to both N03-- and NH/-fed plants over the long term. From this it can be concluded that the lower NUE of NH/-compared to N03--fed plants grown with 5000 ppm root-zone C02 was due to increased N uptake and exudation of organic compounds into the nutrient solution. Experiments with 813C also showed that at increasing rootzone CO2 concentrations, PEPc made a bigger contribution to the carbon budget via the anaplerotic reaction.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om (1) die invloed van verhoogde opgeloste anorganiese koolstof dioksied (DIC) op die stikstofverbruiksdoeltreffenheid (NUE) van plante wat op verkillende stikstofbronne gekweek is, te bepaal. (2) Veranderinge in die regulering van nitraat reduktase (NR), fosfo-enolpirovaatkarboksilase (PEPc) en karboonsuuranhidrase (CA) is bestudeer en gekorreleer met waargeneemde verskille in NUE. (3) 'n Beraming van die mate waartoe verhoogde DIC bydra tot die koolstofbegroting van plante, gekweek op verskillende stikstofbronne, word bespreek. Lycopersicon esculentum cv. F144 saailinge is in waterkultuur (pH 5.8) met 2 mM N03- of NH/ gekweek en die oplossings is alternatiewelik met 0 ppm of 5000 ppm CO2 belug. Die NUEs van plante gekweek met NH/ en belug met albei C02 konsentrasies was vergelykbaar grootliks as gevolg van hulooreenkomstige relatiewe groeitempo's en Nopname. DIC het aanvanklik NH/ opname gestimuleer, maar enige latere stimulerende effek van DIC op fisiologiese prosesse was klaarblyklik uitgekanselleer deur N~ + toksiteit veroorsaak deur vertraagde assimilasie. Die NUE van plante gekweek met N03- en 5000 ppm CO2 was hoër as dié van plante gekweek met N03- en 0 ppm CO2. Dit is moontlik gekoppel aan hoër relatiewe groeitempo's teenoor onveranderde N opname tempo's. Plante gekweek met N03- en 5000 ppm CO2 het hoër in vivo NR en in vitro NR en PEPc aktiwiteite getoon as plante gekweek met N03- en 0 ppm CO2. Bogenoemde toenames in ensiem aktiwiteite word verbind met biomassa toename deur verhoogde organiese suur sintese. Dit bied 'n moontlike verklaring vir die hoër relatiewe groeitempo's van plante gekweek met N03- en 5000 ppm CO2 teenoor plante gegroei met N03- en 0 ppm CO2. Die 015N waardes van plante gekweek met NH/ en 5000 ppm CO2 was meer positief as dié van plante gekweek met Nl-l,+ en 0 ppm CO2 wat gedui het op die afwesigheid van ensiematiese diskriminasie. Dit kon as gevolg gewees het van die vertragende effek van DIC op Nl-la + opname wat daartoe sou lei dat die plante beide isotope eweveel inkorporeer. Eksperimente met ol3C het getoon dat PEPc oor 'n lang tydperk eweveel begedra het tot die koolstofbegroting van plante gekweek met beide N03- and N~+. Hiervan kan afgelei word dat die laer NUE van plante gekweek met NH4 + en 5000 ppm C02 in vergelyking met dié van plante gekweek met N03- en 5000 ppm CO2 die gevolg was van verhoogde NH/ opname en uitskeiding van aminosure in die voedingsoplossing. Eksperimente met 0"c het ook getoon dat verhoogde DIe konsentrasies die bydrae van PEPc tot die plant se koolstofbegroting laat toeneem.

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Morris, Jerry Whitaker. "Influence of nitrogen fertilization and leaf management on nitrogen use efficiency and agronomic performance of mammoth cultivars of flue-cured tobacco /." This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-08182009-040605/.

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Moon, J. W. Jr, D. A. Bailey, E. Fallahi, R. G. Jensen, and G. Zhu. "Effect of Nitrogen Application on Growth and Photosynthetic Nitrogen use Efficiency in Two Ecotypes of Wild Strawberry, Fragaria chiloensis (L.) Duchn." College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/215746.

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The relationships between increasing nitrogen fertilization and growth, maximum CO₂ assimilation and the initial slope of the CO₂ response curve were studied in two ecotypes of wild strawberry, Fragaria chiloensis (L) Duchn. Nitrogen accumulation of CA11, an ecotype from a low -nutrient dune site, was greater at all nitrogen concentrations than that of RCP37, an ecotype from a higher- nutrient strand site. Maximum CO₂ assimilation, total Rubisco activity, dry weight, and initiation of leaves and crowns were higher in CA11 than RCP37 as nitrogen treatment was increased from 0 to 200 mg l⁻¹, whereas these parameters were lower in CA11 when fertilized at 300 mg l⁻¹, but not in RCP37. The mean leaf area of CA11 was greater than RCP37 when grown with no supplemental nitrogen, but mean leaf area of the two lines was similar under nitrogen fertilization. Maximum CO₂ assimilation and carboxylation efficiency increased with increasing leaf nitrogen in both clones. At equivalent concentrations of leaf nitrogen, RCP37 had higher CO₂ assimilation and carboxylation efficiency than CA11 and the difference between the 2 clones increased as leaf nitrogen increased. Thus, RCP37 had a higher photosynthetic nitrogen use efficiency than CA11. However, at a given applied nitrogen level, CA11 allocated more nitrogen to a unit of leaf area so that photosynthetic rates were higher than RCP37, except at the highest application of 300 mg l⁻¹. The high nitrogen accumulation capacity and resource allocation to fruiting structures (crowns) in CA11 lead us to suggest that this clone may possess genes that could increase fruit yield in cultivated strawberry.

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Murray, Cynthia Ruth. "Genotypic differences in nitrogen use efficiency in timothy (Phleum pratense) and tall fescue (Festuca arundinacea)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0016/MQ57316.pdf.

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Doerge, Thomas A., and T. Curt Tucker. "The Effect of Nitrification Inhibitors on Nitrogen Use Efficiency in Drip and Furrow Irrigated Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 1987. http://hdl.handle.net/10150/204469.

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The use of nitrification inhibitors delays the conversion of ammonium fertilizers to the nitrate form and has the potential to increase nitrogen use efficiency in irrigated agriculture. Two field experiments were conducted at the Maricopa Agricultural Center in 1986 to evaluate the effect of two nitrification inhibitors (N-Serve and an experimental compound, ACP) on the growth, yield, nitrogen uptake, and fertilizer use efficiency obtained by growing cotton using buried-drip and furrow irrigation. ¹⁵N labeled ammonium sulfate was applied with and without nitrification inhibitors at the beginning of the season. Whole plant samples were taken at the end of the season to determine N uptake efficiency. No significant differences in growth, lint yield or N uptake efficiency were detected due to the application of either inhibitor. The conditions where nitrification inhibitors might improve nitrogen use efficiency in furrow irrigated cotton production are discussed.

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Hippenstiel, Friederike [Verfasser]. "Energy and nitrogen use efficiency in farm animal nutrition : opportunities and limitations for improvement / Friederike Hippenstiel." Bonn : Universitäts- und Landesbibliothek Bonn, 2013. http://d-nb.info/1043057803/34.

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Schuba, Jan [Verfasser]. "Nutritional strategies to optimize efficiency of nitrogen use by lactating dairy cows : kumulative Dissertation / Jan Schuba." Halle, 2018. http://d-nb.info/1160235554/34.

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Garabet, Sonia. "Fertilizer use efficiency and nitrogen dynamics in rainfed and irrigated wheat under a Mediterranean-type climate." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262036.

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Alpuerto, Jasper Benedict Battad. "Physiological, Metabolic, and Transcriptional Analysis of Submergence Tolerance in Rice and Nitrogen Use Efficiency in Wheat." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/92003.

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Flooding is a major environmental stress that damages agricultural production worldwide. Using the key regulator of submergence tolerance in rice, SUB1A, as a model, we have advanced our understanding of how plants coordinate transcriptional, hormonal, and metabolic responses to submergence. However, the contribution of SUB1A to recovery from sublethal submergence is still unknown. This study revealed SUB1A's additional role in the recovery phase: promotion of a rapid return to normal metabolic status upon desubmergence through quick recovery of photosystem II photochemistry and carbon fixation. We also investigated how SUB1A differentially regulates adaptive responses in two functionally distinct leaves, growing and mature leaves, under submergence. This study revealed that rice plants promote rapid carbohydrate and nitrogen remobilization and transport in mature leaves, supporting quick elongation growth of growing leaves. In the presence of SUB1A, these metabolic processes were suppressed in mature leaves, resulting in the avoidance of energy starvation in the source tissues. In growing leaves, SUB1A enhanced the accumulation of abscisic acid, but repressed the level of ACC, a precursor of ethylene, contributing to the restriction of elongation growth and leaf senescence in the sink tissues. Application of nitrogen fertilizers is a necessary step to maintain high grain yield in cereals, but plants absorb only 30-50% of supplied N. Wheat, one of the most widely grown crops in the world, requires a high level of nitrogen application to maintain grain yield and protein content. In this study, we investigated how nitrogen input affects the accumulation of major N and C compounds and expression of genes associated with N and C metabolism in flag leaves of wheat. We used two genotypes with distinct nitrogen use efficiencies (NUE), VA08MAS-369 and VA07W-415. VA08MAS-369 displayed higher grain yield, stover biomass, and stover N content at low N, which results from greater N-uptake efficiency in this genotype. Consistently, high N-uptake efficiency was reflected by increased mRNA accumulation of nitrate transporters and their transcriptional regulator, NAC2, in flag leaves at the post-anthesis stage. Overall, this study advanced our knowledge of the important mechanisms in plant response to flooding and N limitation in these key staple cereals.
PHD

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42

Tucker, Andrew Neil. "Managing nitrogen in grain sorghum to maximize N use efficiency and yield while minimizing producer risk." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1424.

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43

Grahmann, Kathrin [Verfasser]. "Nitrogen use efficiency and optimization of nitrogen fertilizer application for stable yields and high quality of cereals grown in conservation agriculture / Kathrin Grahmann." Kassel : Universitätsbibliothek Kassel, 2017. http://d-nb.info/1126457035/34.

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Mendes, Bastos Leonardo. "N fertilizer source and placement impacts nitrous oxide losses, grain yield and N use efficiency in no-till corn." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18797.

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Master of Science
Department of Agronomy
Charles W. Rice
Agricultural lands receiving N inputs are considered the primary source of N2O, a potent greenhouse gas. N fertilizer management has shown variable effects on both N2O losses and corn grain yield. The objectives of this study were to assess the impact of N source and placement on N2O emissions, fertilizer-induced emission factor (FIEF), corn grain yield, yield-scaled N2O emissions (YSNE) and N fertilizer recovery efficiency (NFRE). The experiment was conducted from 2013 through 2014 at the Agronomy North Farm located at Kansas State University, Manhattan, KS. The soil was a moderately well-drained Kennebec silt loam. The treatments were broadcast urea (BC-Urea), broadcast urea ammonium nitrate (UAN) (BC-UAN), broadcast coated urea (BC-CU), surface-band UAN (SB-UAN), subsurface-band UAN (SSB-UAN), subsurface-band UAN + nitrification inhibitor (SSB-UAN+I) and a 0 N control. In 2013, SSB- UAN emitted significantly more N2O (2.4 kg N2O-N ha-1), whereas control (0.3 kg ha-1) and BC- UAN (0.6 kg ha-1) emitted the least. In 2014, most treatments emitted between 3.3 and 2.5 kg N2O-N ha-1. Only SSB-UAN+I (1.03 kg ha-1) and control (0.26 kg ha-1) were significantly lower. The use of a nitrification inhibitor decreased N2O emissions by 62% and 55% in 2013 and 2014, respectively. BC treatments had cumulative emissions significantly higher in 2014 compared to 2013. Only SSB-UAN+I had a significantly lower FIEF (0.4%), and 2013 FIEF (0.68%) was significantly lower than that of 2014 (1.38%). In 2013, banded treatments had significantly higher grain yields (from 9.1 to 10.5 Mg ha-1), whereas in 2014 fewer differences among N treatments were observed, ranging from 7.2 to 8.6 Mg ha-1. Banded treatments had significantly lower grain yields in 2014 compared to 2013. Only BC-UAN and SSB-UAN+I had significantly lower YSNE, and 2013 had lower YSNE than 2014. In 2013, SSB-UAN had the greatest NFRE, whereas BC treatments had the lowest. In 2014, N treatments did not differ in NFRE. SSB-UAN and SSB-UAN+I had significantly lower NFRE values in 2014 compared to 2013. Fertilizer source and placement have the potential to mitigate N2O emissions and promote high yields and NFRE in corn, however, the response is dependent on the rainfall pattern after fertilizer application. The option of banding UAN without any additive promoted higher N2O losses on a year when precipitation was well distributed, but also enhanced grain yield and NFRE. On the other hand, under the same precipitation conditions, broadcasting N fertilizer promoted lower N2O losses, grain yield and NFRE, but those were all improved in a wet year. Therefore, the subsurface band placement would be the best option under a normal year, whereas broadcasting fertilizer would be the best option under a wetter year. Further, the use of NI with subsurface band UAN provides the most sustainable option, since the NI decreased N2O losses compared to UAN alone in both years. Further research should evaluate N source and placement combinations under different environments in order to better understand how they impact crop performance and the negative environmental aspects of N fertilization. It is important to test those treatments under different precipitation scenarios and look for trends that indicate the best N management option at the local level.

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Weber, Holly S. "Use of nitrogen management products and practices to enhance yield and nitrogen uptake in no-till corn and grain sorghum." Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4096.

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46

Leung, Kin-heung Ray, and 梁健鄉. "How to use networking to increase internal efficiency and then increase external effectiveness in an international environment." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31268110.

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Leung, Kin-heung Ray. "How to use networking to increase internal efficiency and then increase external effectiveness in an international environment /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18831266.

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Satterfield, Jason Morris. "Evaluation of technology aimed to improve nitrogen use efficiency for delayed-flood rice (Oryza sativa L.) production." Master's thesis, Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-03262009-094038.

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Redfern, James. "Performance of cereal aphids in relation to genetic variation and nitrogen use efficiency of wheat (Triticum aestivum)." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/59627/.

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In this thesis I address the question: does breeding to improve nitrogen use efficiency of winter wheat, Triticum aestivum, increase its susceptibility to infestation by cereal aphids? Laboratory and greenhouse experiments were used to monitor population performance of the aphids Sitobion avenae and Metopolophium dirhodum on double haploid genotypes of a Savannah cross Rialto (SavRia) wheat population. The genotypes varied in nitrogen use efficiency and its two components: nitrogen uptake efficiency and nitrogen utilisation efficiency. A quantitative trait loci analysis, using 94 genotypes grown under greenhouse and laboratory conditions, identified genetic markers associated with individual performance and population measures of S. avenae and M. dirhodum. Twelve markers across chromosomes on the SavRia genetic map were statistically associated with nine of the fourteen aphid performance traits measured. Nine wheat genotypes, representing the range of nitrogen use efficiencies, were used to analyse how aphid development rate, fecundity and intrinsic rate of increase, varied between genotype and whether settling behaviour and preference between genotypes, reflected differences in performance. Significant differences in performance of S. avenae between different genotypes were found but performance was not correlated with plant nitrogen uptake. In a randomised split plot experiment in the field, six SavRia genotypes and both parental varieties were grown under three application rates of nitrogen fertiliser. Significant variation between genotypes and between different nitrogen application rates was observed for eight plant traits, including both nitrogen uptake and utilisation efficiencies. Density of S. avenae differed significantly between genotypes with significant genotype x nitrogen application rate interactions. Aphid densities were not significantly correlated to either components of nitrogen use efficiency. I conclude that this study does not support the hypothesis that increasing nitrogen use efficiency, or either of its primary components, increases the susceptibility of winter wheat to infestation by cereal aphids.

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Ouyang, Duosheng. "New fertilizer combinations for improved nitrogen and phosphorus use efficiency and reduced environmental damage in corn production." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0004/NQ30353.pdf.

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Dissertations / Theses on the topic 'Internal nitrogen use efficiency'

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