Made available in DSpace on 2014-08-20T13:44:31Z (GMT). No. of bitstreams: 1 dissertacao_tiago_antonio_webber.pdf: 823767 bytes, checksum: ca2f08e4c6bf55ec83074cc792db19a9 (MD5) Previous issue date: 2009-12-22 / The objective of the present study was to analyze the efficiency of wheat seed production and conditioning at the Sementes Estrela seed company located in the Erechim county, RS state, Brazil, during 2006/07, 2007/08 and 2008/09 crop seasons. Data of area and volume registered for seed production, receiving, conditioning and aprovation, germination and comercialization of wheat seed lots. Cultivars studied were: Abalone; Safira; Alcover; Pampeano; Onix; Quartzo; Marfim; BRS Timbauva; BRS Guamirim; BRS 208; Fundacep Nova Era; Fundacep 52; Fundacep Cristalino e Fundacep Raizes. The results shown that wheat seed production at Sementes Estrela represents 3.87% of the state of Rio Grande do Sul production. There is a difference between registered volume and volume received of wheat seeds of about 15%. The efficiency of wheat seed conditioning is increasing each crop season, being the seed loss of about 22%. In the last two crop seasons the wheat seed conditioned and approved is 100%. Germination of approved seed lots is above the standard stablished by the seed company in all crop seasons. Commercialization of wheat seeds at Sementes Estrela company is above 90% of seed lots conditioned but shows a tendency of reducing in the last crop season. / O presente estudo teve como objetivo analisar a eficiência da produção e do beneficiamento de semente de trigo na empresa Sementes Estrela localizada em Erechim, RS, no período que compreende as safras 2006/07, 2007/08 e 2008/09. Para isso, foram levantados dados de volume de área e volume inscritos para produção de sementes, bem como de recebimento, beneficiamento e aprovação, germinação e comercialização dos lotes de sementes de trigo nas safras estudadas. As cultivares de trigo estudas foram: Abalone; Safira; Alcover; Pampeano; Onix; Quartzo; Marfim; BRS Timbauva; BRS Guamirim; BRS 208; Fundacep Nova Era; Fundacep 52; Fundacep Cristalino e Fundacep Raizes. Os resultados mostraram que a produção de sementes de trigo da empresa Sementes Estrela representa 3,87% da área de produção do estado de Rio Grande do Sul.Há uma diferença entre volume inscrito e volume recebido de sementes de trigo da empresa Sementes Estrela de 15%. A eficiência do beneficiamento de sementes de trigo vem aumentando a cada safra, sendo o descarte ao redor de 22%. Nas últimas duas safras de sementes de trigo a aprovação de lotes beneficiados é de 100%. A germinação dos lotes de sementes de trigo aprovados está acima do padrão estabelecido pela empresa. A comercialização de sementes de trigo nas Sementes Estrela está acima de 90% dos lotes ensacados e mostra uma tendência a diminuir na última safra.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / With the objective of evaluating the acting of two seeder-fertilizer prototypes for the direct seeding system, works were developed in field conditions and evaluation track according to international standard. The experiments were conduced in the years of 2007 and 2008, evaluating two prototypes, one of precision seeder-fertilizer and another of multiple seeder-fertilizer. When plan a parallel one among the two prototypes, she allow to affirm that the same ones present similar acting in the evaluations accomplished in track. If compared the results obtained for the appraised prototypes in this study, with the one of other seeders of similar characteristics found in the literature, she can conclude that the same ones present acting similar or else better, when of the same variables answer. In the experiments in field conditions with the two prototypes, the studied variables allow to affirm that the same ones present good acting in the direct sowing of soybean (precision seeder-fertilizer prototype) and wheat (multiple seeder-fertilizer prototype). For the studied cultures, larger sowing densities, in the strip from three to five and from eight to twenty seeds m-1, for the corn cultures and soybean respectively, they reduce the percentile of acceptable spacing s among seeds. / Com o objetivo de avaliar o desempenho de dois protótipos de semeadoras-adubadoras para o sistema plantio direto, foram desenvolvidos trabalhos em condições de lavoura e pista de avaliação conforme norma internacional. Os experimentos foram conduzidos nos anos de 2007 e 2008, avaliando dois protótipos, um de semeadora-adubadora de precisão e outro de semeadora-adubadora múltipla. Quando traçado um paralelo entre os dois protótipos, se permite afirmar que os mesmos apresentam desempenho semelhante nas avaliações realizadas em pista. Se comparados os resultados obtidos nos protótipos deste estudo, com os de outras semeadoras de características semelhantes encontrados na literatura, se pode concluir que os mesmos apresentam desempenho similar senão melhor, quando das mesmas variáveis resposta. Nos experimentos em condições de campo com os dois protótipos, as variáveis estudadas permitem afirmar que os mesmos apresentam bom desempenho na semeadura direta de soja (protótipo de semeadora-adubadora de precisão) e trigo (protótipo de semeadora-adubadora múltipla). Para as culturas estudadas, maiores densidades de semeadura, na faixa de três a cinco e de oito a vinte sementes m-1, para as culturas de milho e soja respectivamente, reduzem o percentual de espaçamentos aceitáveis entre sementes.

The sun is the primary source of all chemical energy on the planet. Starch granules have evolved as storage deposits for captured light energy. Many complex biological functions take place at the starch granule surface, including starch granule metabolism and defense. The starch granule-associated protein puroindoline is a known antimicrobial with unique functional and biological properties, attributed to the presence of a unique tryptophan-rich domain. To test puroindoline's tight association, puroindoline removed from the starch granule surface during water-washing was assessed. Washing more than eight times failed to further reduce puroindoline content of starch granules, suggesting a strong association of puroindoline with the starch granule surface. To identify the tryptophan-rich domain tightly associated with the starch granule surface, we used a combination of in situ tryptic digestion and mass spectrometry. We identified the tryptophan-rich domain of puroindoline directly bound to the starch granule surface of wheat. This is the first instance of the tryptophan-rich domain directly observed at the starch granule surface. In addition, using mass spectrometry, we determined that during development and maturation, wheat seeds appear to have resisted infection and lysed the pathogens where, upon desiccation, the molecular evidence remained fixed at the starch granule surface. Proteins with known antimicrobial activity were identified, as well as several proteins from the plant pathogens Agrobacterium tumefaciens, Pectobacterium carotovorum, Fusarium graminearum, Magnaporthe grisea, Xanthomonas axonopodis, and X. oryzae. Future characterization may reveal previously unknown host-pathogen interactions. Finally, we have demonstrated that puroindoline, when expressed in the seeds of transgenic corn, will localize and associate with the starch granule surface in a pattern similar to the puroindoline expression pattern observed in wheat. Surprisingly, puroindoline expression in transgenic corn is correlated with an increase in total seed oil content.

Orientador: Salatiér Buzetti / Banca: Marco Eustáquio de Sá / Banca: Carlos Alexandre C. Crusciol / Resumo: A utilização de cultivares de trigo de alto potencial produtivo e a adubação nitrogenada são essenciais para obtenção de altas produtividades. Todavia, os estudos sobre a resposta dos componentes de produção e produtividade do trigo à adubação nitrogenada são insuficientes, e devem ser estudadas em condições específicas de ambiente, como a região dos cerrados de baixa altitude, onde há necessidade do uso da irrigação. O objetivo deste trabalho foi avaliar os efeitos de diferentes doses e fontes de N, sendo uma o sulfonitrato de amônio com inibidor de nitrificação (Entec), aplicadas totalmente em semeadura ou em cobertura, em diferentes cultivares de trigo irrigado, sob plantio direto. O experimento foi desenvolvido em área experimental pertencente à Faculdade de Engenharia de Ilha Solteira - UNESP, em Selvíria - MS, em um Latossolo Vermelho Distrófico. O delineamento estatístico foi o de blocos ao acaso, em esquema fatorial 5x3x2x4 (em 2006) e 5x3x2x2 (em 2007), ou seja, cinco doses de N (0, 50, 100, 150 e 200 kg ha-1), três fontes de nitrogênio (Entec, sulfato de amônio e uréia) e duas épocas de aplicação (semeadura ou cobertura). Em 2006, foram utilizados quatro cultivares de trigo (E 21, E 22, E 42 e IAC 370), com 3 repetições. Já em 2007, foram utilizados os cultivares E 21 e IAC 370, com 4 repetições. Os cultivares mais produtivos foram o IAC 370 e E 21. Não houve diferença entre o Entec, sulfato de amônio e uréia para produtividade de grãos e para maioria dos componentes de produção. A aplicação do N totalmente em semeadura ou em cobertura foram semelhantes no desempenho da cultura. O teor de N foliar e o teor de clorofila (SPAD) correlacionam-se positivamente, comprovando a relação nitrogênio e clorofila. As doses de nitrogênio influenciaram o teor de N foliar, teor de clorofila (SPAD) e aumentaram a produtividade de grãos ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The use of wheat cultivar of high productive potential and the nitrogen fertilization are essential to get high income. Though, the studies about the response of the production components and productivity of wheat to nitrogen fertilization are insufficient, and it should be studied in specific environmental conditions, as the savannah area of low altitude, where there is need the use of irrigation. The objective of this work was to evaluate the effects of different doses and sources of N, using one ammonium sulfonitrate with nitrification inhibitor (Entec), applied totally at sowing or at covering, in different wheat cultivars irrigated, under no till. The experiment was conducted at experimental area belonging to UNESP - Ilha Solteira Campus, located in Selvíria - MS, in an Acrustox. A randomized block design was used, in a factorial scheme 5x3x2x4 (in 2006) and 5x3x2x2 (in 2007), being five doses of N (0, 50, 100, 150 and 200 kg ha-1), three sources of nitrogen (Entec, ammonium sulfate and urea) and two application times (at sowing or at covering). In 2006, it was used four wheat cultivars (E 21, E 22, E 42 and IAC 370), with 3 repetitions. In 2007, it was used just the two best cultivars: E 21 and IAC 370, with 4 repetitions. The IAC 370 and E 21 wheat cultivars presented the highest productivity. There was no difference among Entec, ammonium sulfate and urea for grain yield and for majority of the production components. To the application of N totally at sowing or at covering it there was not difference between them. The N leaf and the chlorophyll contents (SPAD) were correlated positively, proving the relationship between nitrogen and chlorophyll contents. The doses of nitrogen influenced the N content, chlorophyll content (SPAD) and they increased the grain yield up to the dose of 118,5 kg ha-1 of N, independent of cultivar, source of N and application time. / Mestre

The objective of this study was to identify DNA markers for each of six added C-genome chromosomes in Triticum aestivum L. cv. 'Alceso'-Aegilops caudata L. addition lines using the randomly amplified polymorphic DNA (RAPD) technique. DNA from Ae. caudata, T. aestivum, amphiploid of T. aestivum X Ae. caudata, and six disomic addition lines of wheat having a pair of Ae. caudata chromosomes was used as the template for the amplification of RAPD markers with a total of 58 random 10-mer oligonucleotide primers. Two primers, OPC-08 and OPJ-16, produced one intense band each from the amphiploid of T. aestivum X Ae. caudata and Ae. caudata, which was absent in all six addition lines. Each of these two primers produced a chromosome marker that could be tentatively located to the chromosome CA of Ae. caudata. OPJ-02, OPD-12, OPD-02, OPJ-12, OPD-20, and OPJ-14 produced a marker each for CB, CC, CD, CE, CF, and CG, respectively. OPJ-09 produced C-genome chromosome-specific RAPD markers. Also, OPC-05 and OPJ-19 produced RAPDs from both wheat and Ae. caudata genomes.

The use of nitrogen (N) fertilizers is both costly to farmers and contributes to environmental degradation. N applied to wheat accounts for 18% of N applied to farmland globally, making it a prime target for reducing and optimizing N application. Chapter I is a review on nitrogen use efficiency (NUE) in wheat, with emphasis on breeding efforts and genetic resources available to increase NUE. The concept of effective use of nitrogen (EUN) as yield per unit N applied as a measure of N use, is also introduced. Chapter II is a study using two bi-parental double haploid families to evaluate genetic variability of both the genetic main effects (intercept) and linear response to N (slope) and determine the feasibility of selection for EUN in wheat. Using cross validation, a genomic prediction accuracy of 0.68 for intercept and 0.50 for slope was found, indicating that EUN is under genetic control and can be selected for. The prospect of breeding for EUN under limited resources, i.e., using fewer N rates and fewer experimental plots, is also explored. It was found that two different N treatments can be used to produce accurate predictions of intercept and slope as high as 0.98 and 0.95, respectively. Chapter III uses the same population described in chapter II to further investigate feasibility of selection for EUN using a normalized difference vegetation index (NDVI) obtained from multi-spectral aerial images gathered throughout the growing season. Cumulative photosynthesis across the growing season was estimated by integration across the NDVI curve, and compared to grain yield estimates to determine the efficacy of aerial imaging to identify high EUN lines. NDVI values and the area under the NDVI curve were able to predict yield and had the strongest ability to predict yield in moderate to low N treatments, with R2 values as high as 0.81 and 0.78 respectively. / Master of Science / Chapter I is a review on nitrogen use efficiency (NUE) in wheat, with emphasis on breeding efforts and genetic resources available to increase NUE. The concept of effective use of nitrogen (EUN) defined as grain yield per unit N applied, is contrasted to NUE as a more economic breeding goal. Chapter II uses two bi-parental mapping populations to evaluate genetic variability of both the genetic main effects and the linear response to N and determine the feasibility of selection for EUN in wheat. The efficacy of genomic prediction for EUN is explored and the prospect of breeding for EUN under limited resources is also explored. Chapter III uses the same populations described in chapter II to further investigate the feasibility of selection for EUN using a normalized difference vegetation index (NDVI) obtained from multi-spectral aerial images gathered throughout the growing season. Cumulative photosynthesis across the growing season was estimated and found to be predictive of grain yield estimates at accuracies ranging from 0.31 to 0.78.

Powdery mildew, caused by the pathogen Blumeria graminis (DC) Speer (Syn. Erysiphe graminis DC) f. sp. tritici, is a major disease of wheat (Triticum aestivum L.). Race-specific resistance is easily identified in the field due to its qualitative phenotype and it is easy to incorporate because it is inherited as a single gene. Unfortunately, this type of resistance is easily overcome by the pathogen. Traits associated with quantitative trait loci (QTL) such as adult-plant resistance (APR), have become popular with plant breeders because of their durability over a wide geographic range and time. Due to the quantitative nature of these genes, they are difficult to study requiring multiple assessments of disease development under natural conditions in more than one location over a period of several weeks. Numerous QTL for APR to powdery mildew have been mapped in independent studies in different wheat backgrounds. The wheat cultivar Massey has been the subject of several studies due to its APR to powdery mildew that has remained effective for several decades. However, it has been difficult to identity simple sequence repeat (SSR) markers that are tightly linked to the QTL for APR in Massey. Such markers give breeders an advantage by allowing them to quickly identify and select for traits that would be difficult to distinguish in the field among breeding progeny from several backgrounds. Therefore, identification of tightly linked markers associated with APR to powdery mildew is necessary so that these traits can be selected for reliably in progeny. / Master of Science

Wheat (Triticum aestivum, L) and barley (Hordeum vulgare) are widely grown as winter annual grains in a double crop rotation with soybean (Glycine max, L. Merr.) in much of the U.S. Improved management strategies and the development cultivars that meet the quality requirements of higher value end-use markets is important to increase production and profitability of winter annual grains and the double crop rotation in the Eastern U.S. In Chapter I, fifteen commercially relevant winter wheat genotypes ranging in maturity were sown in a split-plot design (sowing date=main plot, genotype=subplot) at three different sowing dates (considered to be 'very early' (20-28 days before recommended), 'early (6-11 days before recommended)', or 'recommended') and replicated three times at eight environments (site-year) from 2015-2018 in VA and KY. Grain yield, tiller estimation, heading date, protein, and 1000-kernel weight were assessed for each yield plot. At all environments, sowing earlier in the fall achieved an earlier (P<0.05) heading date, while grain yields varied depending on environment and genotype. Genotype by sowing date interactions were non-significant (P<0.05) at five site-years and significant (P<0.05) at three site-years. Molecular markers can be associated with phenotypic traits via quantitative trait loci (QTL) mapping, these markers can be used by breeders in marker assisted selection (MAS) to indirectly select phenotypic traits that are difficult or expensive to measure. In Chapter II, the genetic architecture of end-use quality is investigated in two soft red winter wheat bi-parental (Pioneer '25R47' / 'Jamestown' and Pioneer '26R46' / 'Tribute'). Both populations were genotyped with a public 90,000 wheat iSelect SNP-Array, grown over two crop seasons at two Virginia sites, evaluated for quality traits at the USDA-ARS Soft Wheat Quality Lab (SWQL), and analyzed with QTL mapping. This chapter describes a total of 24 putative QTL that were identified on 13 different chromosomes and associated with grain characteristics, milling, and/or baking performance along with phenotypic data for both populations, other putative QTL, and transgressive progeny with exceptional flour yield and cookie diameters. A region on 3A (Qfy.vt.3A.Jtwn) is a strong candidate to be utilized for MAS in soft red winter wheat breeding programs as it explained 6.9-10.3% (Pioneer 25R47 / Jamestown) and 4.6-17.0% (Pioneer 26R46 / Tribute) of the phenotypic variation for flour yield. In Chapter III, malt quality genetic structure was investigated in two winter 'malt x feed' doubled haploid barley breeding populations. Both populations were genotyped with the iSelect InfiniumTM SNP assay consisting of 50,000 barley SNPs, grown in two to three Virginia environments (Blacksburg and Warsaw) during 2017 - 2019, and characterized for 11 phenotypic traits associated with malting quality. QTL mapping validated six previously reported regions (Mohammadi, et al., 2015, GrainGenes 3.0, 2019) that are strongly associated (LOD > 3.0) with relevant malt quality traits. Phenotypic variation for malt quality was largely and consistently explained by QTL on chromosomes 1H, 5H, and 7H in the Endeavor / VA09B-34 population and by two separate QTL on 1H in the Violetta / VA09B-34 population. A region on 4H corresponding with QDp.DiMo-4H, explained between 12.1 - 42.2% (Endeavor / VA09B-34) and 30.0 - 55.7% (Violetta / VA09B-34) of the phenotypic variation for diastatic power (DU). These QTL are recommended for MAS in order to aid breeding strategies that aim to select for improved malting characteristics in Eastern U.S. malt barley breeding material. / Doctor of Philosophy / Wheat (Triticum aestivum, L) and barley (Hordeum vulgare) are staple crops throughout the world, and are the third and fourth most produced cereals crop according to the FAO. Primarily grown for human consumption, wheat and barley provide a significant percentage of the nutritional requirements for the human populations. According to the United Nations, wheat contributes 20% of all calories consumed by humans. Barley is the primary ingredient used to make beer. Increased productivity of all cropping and livestock systems is required in order to feed a growing human population while also restoring and preserving natural ecosystems. This can be accomplished through breeding and improved cropping systems management. Planting of existing cropland more frequently is fundamental to the improvement of cropping system productivity. In much of the U.S. (southern two-thirds of the lower 48), annual winter grains such as wheat and barley can be grown over the winter and spring in between the typical corn (Zea mays subsp. mays) and soybean (Glycine max, L. Merr.) growing seasons. Therefore, producing three crops in two years, as opposed to only two. Only between 6 and 11 million acres are double cropped in the US annually, for perspective, in 2018, 89 million acres of both corn and soybeans, which can only grow in summer, were planted. Over half of the soybean (~45 million) acres in Midwestern and Southeastern states could support double cropping. This is a major opportunity to maximize output per unit area, freeing up less productive land to be restored as natural ecosystems, potentially increasing carbon sequestration and species biodiversity. Winter annual grains have a very similar composition (high carbohydrate, low protein and oil) to corn, and could fill similar end-use markets currently dominated by corn (i.e. ethanol or livestock feed). For double cropping to be more widely deployed, it must be more profitable. Increased profitability of growing three crops in two years as opposed to two must outweigh the added cost of planting, managing, harvesting, and marketing the additional winter crop. Therefore, it is important to investigate management strategies that could increase production per unit area and develop new winter annual cultivars with improved end-use characteristics in order to make the winter annual more desirable to the end-users. Chapter I investigates sowing winter wheat earlier in the fall (i.e. 1st week of Oct. or last week of Sept.) in order to achieve an earlier harvest in the spring and earlier soybean planting (yield decreases 0.5 to 1 bu/ac per day that sowing is delayed), while also offering other benefits such as better-established root systems going into winter, which improves water infiltration and reduces erosion. At all environments, sowing earlier in the fall achieved an earlier heading date, while grain yields varied depending on environment and genotype. Genotype by sowing date interactions were non-significant at five site-years and significant at three site-years. Chapters II and III investigate the genetic architecture of winter wheat and winter barley breeding populations for end-use quality traits (milling/baking and malting). This was done in order to identify molecular markers that could be used to screen breeding material for improved end-use quality. The markers could then be used to assist breeders in developing soft red winter wheat cultivars with greater flour yields/improved baking performance and winter malt barley cultivars that can be grown in the Eastern U.S. and are suitable for the craft beer market. Chapter II describes 24 genomic regions that influences milling/baking performance in two soft red winter wheat breeding populations. Chapter III describes 6 genomic regions that influence malting performance in two winter barley breeding populations.

In multiple species, genome-wide association (GWA) studies have become an increasingly prevalent method of identifying the quantitative trait loci (QTLs) that underlie complex traits. Despite this, relatively few GWA analyses using high-density genomic markers have been carried out on highly quantitative traits in wheat. We utilized single-nucleotide polymorphism (SNP) data generated via a genotyping-by-sequencing (GBS) protocol to perform GWA on multiple yield-related traits using a panel of 329 soft red winter wheat genotypes grown in four environments. In addition, the SNP data was used to examine linkage disequilibrium and population structure within the testing panel. The results indicated that an alien translocation from the species Triticum timopheevii was responsible for the majority of observed population structure. In addition, a total of 50 significant marker-trait associations were identified. However, a subsequent study cast some doubt upon the reproducibility and reliability of plant QTLs identified via GWA analyses. We used two highly-related panels of different genotypes grown in different sets of environments to attempt to identify highly stable QTLs. No QTLs were shared across panels for any trait, suggesting that QTL-by-environment and QTL-by-genetic background interaction effects are significant, even when testing across many environments. In light of the challenges involved in QTL mapping, prediction of phenotypes using whole-genome marker data is an attractive alternative. However, many evaluations of genomic prediction in crop species have utilized univariate models adapted from animal breeding. These models cannot directly account for genotype-by-environment interaction, and hence are often not suitable for use with lower-heritability traits assessed in multiple environments. We sought to test genomic prediction models capable of more ad-hoc analyses, utilizing highly unbalanced experimental designs consisting of individuals with varying degrees of relatedness. The results suggest that these designs can successfully be used to generate reasonably accurate phenotypic predictions. In addition, multivariate models can dramatically increase predictive accuracy for some traits, though this depends upon the quantity and characteristics of genotype-by-environment interaction. / Ph. D. / Quantitative traits are those traits that can display a wide range of variability within a population of individuals. These traits are influenced by the interaction of many different genes, and are also influenced by the environment to varying degrees. Traditionally, geneticists who studied quantitative traits had to rely on statistical models, while the biological causes of variation in the expression of these traits remained largely unknown. However, the advent of DNA marker technology granted geneticists the ability to identify specific regions of the genome that highly influence quantitative traits. Many studies have since attempted to find these <i>quantitative trait loci</i> (QTLs) across a wide range of traits and species. However, we are faced with something of a paradox when we attempt to find QTLs. Theory tells us that an idealized, truly quantitative trait arises due to the effects of many genes, each with an infinitesimal effect on the trait in question. Therefore, the more quantitative a trait, the fewer QTLs we should expect to find. In addition, QTLs may not be reliable, due to the effects of different environments and different genetic backgrounds within a population. A more recent trend involves using all available marker data simultaneously to predict a particular line’s performance. This method entails ignoring the genomic underpinnings of a trait, and instead focusing solely on its expression, much like classical quantitative genetics. The obvious downside of this method is that it cannot be used to increase our understanding of what is giving rise to the variations in the trait’s expression that we observe. The studies described in this dissertation were designed to 1) test whether we could identify QTLs for highly quantitative yield-related traits in winter wheat, 2) test the reliability of identified QTLs, and 3) use the DNA marker data to instead generate predictions of line performance. The results indicate that while we can identify QTLs for highly quantitative traits in winter wheat, these QTLs may not be very reliable. Therefore, predictive models may be a good alternative to identifying QTLs, and these methods can be readily implemented within breeding programs.

Soybean and wheat are important crop species due to their significance for human consumption, animal feed, and industrial use. However, increasing global population and worsening climate change have put a major strain on the production system of these crops. Natural disasters such as flooding and drought can severely impact growth and productivity of these crops. In addition, increased application of synthetic nitrogenous fertilizers to meet the global food demand has led to environment related issues. Therefore, with a goal of understanding mechanisms of flooding and drought tolerance in soybean and nitrogen-use-efficiency in wheat, we explored their physiological and transcriptomic regulation. We characterized the fundamental acclimation responses of soybean to flooding and drought and compared the metabolic and transcriptomic regulation during the stresses in a tissue-specific manner. We demonstrated the dynamic reconfiguration of gene expression and metabolism during flooding, drought, and recovery from these stresses. Our study displayed that flooding triggers more dramatic adjustments than drought at the transcriptional level. We also identified that the soybean genome encodes nine members of group VII ERF genes and characterized their responses in leaves and roots under flooding and drought. Based on the expression patterns, it is estimated that two of the nine genes are promising candidate genes regulating tolerance to submergence and drought. In addition, our genome-scale expression analysis discovered commonly induced ERFs and MAPKs across both stresses (flooding and drought) and tissues (leaves and roots), which might play key roles in soybean survival of flooding and drought. In wheat, we evaluated the effect of three different nitrogen rates on yield and its components across four diverse soft red winter wheat genotypes. The cultivar Sisson displayed superior performance in grain yield and nitrogen use efficiency at low nitrogen levels. Our results suggested that improvement of nitrogen use efficiency in low nitrogen environments can be achieved through the selection of three components: grain number/spike, 1000-seed weight, and harvest index. Overall, this study has advanced our understanding of how plants respond to abiotic stresses such as flooding, drought, and nutrient limitation conditions. / Ph. D. / Soybean and wheat are commercially important crop throughout the world. Soybean is a major source of protein and oil for humans, livestock and industrial products including biofuel production. Similarly, wheat is a major source of food products such as bread, pasta, and cookies. However, increasing global population and worsening climate change have put a major strain on the production system of these crops. Natural disasters such as flooding and drought are on the rise, which have severely impacted soybean growth and productivity. In addition, increased application of synthetic nitrogenous fertilizers in wheat production to meet the global food demand has led to environment related issues. Therefore, a mechanistic understanding of flooding and drought tolerance in soybean and nitrogen use efficiency in wheat is of utmost importance. The knowledge obtained from these studies can aid in the development of new varieties in these crops. Here, we carried out our study on soybean by imposing either complete submergence or restricting water supply to characterize the responses to these stresses in shoot and root systems. We found several compounds and genes that were altered distinctly under these two water-related stresses. In addition, we identified some promising genes that can significantly regulate tolerance in soybean to flooding and drought in soybean. To study wheat nitrogen use efficiency, we selected four diverse soft red winter wheat varieties and grew them under three nitrogen levels. We found that the cultivar Sisson has the lowest yield penalty among the four varieties resulting from low nitrogen conditions. In addition, we also demonstrated that three yield traits (grain number per spike, 1000-seed weight, and harvest index) are important selection targets to develop high nitrogen use efficiency varieties.