Peanut (Arachis hypogaea L.) is second major legume crop grown after soybean in the United States, and its productivity is often limited by drought stress. Drought negatively impacts the yield and quality of peanut. Drought stress in peanut causes an annual loss of approximately $520 million in the United States. Improving peanut yield under water deficit conditions is crucial for peanut growers to maintain their profitability in the market. To achieve this, it is essential to either breed or adopt already available drought tolerant cultivars that can produce higher yield under water deficit conditions. Therefore, the objectives of this research were to (1) evaluate five commercially available virginia and runner type peanut cultivars for pod yield stability using multilocation trials by studying G x E interaction across 13 environments including year, location, and irrigation regime. Linn and Binns, AMMI, Shukla, Wricke's, Finlay and Wilkinson stability models were used to determine pod yield stability. Bailey and Sullivan showed higher stability and adaptability across all stability indices whereas Wynne and TUFRunner presented high mean productivity with lesser stability across environments reflecting specific adaptation to just a few environments. Bailey and Sullivan are recommended for sustainable production across the growing region of Virginia and Carolinas. The second objective (2) was identification of drought tolerance related quantitative trait loci (QTL) and genetic markers to facilitate the development of drought tolerant cultivars. Three diverse recombinant inbred line (RIL) populations, derived from crossing lines N05006 x N04074FCT (Pop-1), line N05006 x Phillips, an old virginia-type cultivar (Pop-2), and lines N08086olJCT x PI 585005 (Pop-3) were phenotyped for the Normalized Difference Vegetation Index (NDVI), Canopy Temperature Depression (CTD), SPAD-meter relative chlorophyll content of the leaves (SPAD) and wilting for QTL mapping. Mapping identified 27 minor QTL on eight chromosomes for all physiological characteristics, i.e NDVI, CTD, SPAD and wilting, with logarithmic of odds values ranging from 2.5 to 38.5 and the phenotypic variance explained by these traits from 1.04 to 11.46 %. There were 4 loci on chromosome 2 associated with NDVI in Pop-1 and Pop-3, explaining 1.8 to 10.38% of the phenotypic variation. These genomic regions may be important resources in peanut breeding programs to improve drought tolerance. Further research is needed to increase the marker density in order to fine map the identified QTL and validate markers linked with these regions. / Doctor of Philosophy / Peanut is a multi million-dollar industry in the United States, but water limitations have a detrimental impact on yield, quality, and grower income. Drought along with aflatoxin contamination are two major challenges faced by U.S peanut industry. Annual losses to peanut caused by drought are around $520 million in the United States. Irrigation can alleviate water shortage in drought prone regions, but around 65% of peanut production in U.S is under rainfed condition, meaning that only rainfall can satisfy peanut crop water requirements. The most feasible and economical solution to peanut growers under these circumstances is to adopt drought tolerant varieties. In this research, our goal was to facilitate breeding drought tolerant cultivars through identification of molecular markers associated with drought tolerance and to identify already available drought tolerant peanut cultivars that could be a game changer for the producers. Therefore, the objectives of my research were to (1) evaluate in multiple environments five commercially available virginia and runner type peanut cultivars for pod yield stability and grade factors. In this study, we considered 13 environments, including 4 years, 4 locations, and 2 water regime. Statistical tools including Linn and Binns, AMMI, Shukla, Wricke's, and Finlay and Wilkinson were used to determine pod yield stability. These stability indices showed that Bailey and Sullivan are more stable and adaptable across different locations in terms of yield, whereas Wynne and TUFRunner presented high mean yield with lesser stability showing specific adaptation to only few environments. Based on stability analysis, Bailey and Sullivan are recommended for sustainable production across different growing region of Virginia and Carolinas. The second objective (2) was to identify drought tolerance related genomic regions using three mapping populations. Phenotyping and genotyping of three diverse recombinant inbred line (RIL) populations, derived from crossing lines N05006 x N04074FCT (Pop-1), lines N05006 x Phillips, an old virginia-type cultivar (Pop-2), and lines N08086olJCT x PI 585005 (Pop-3) were done to find quantitative trait loci (QTL) for drought related traits. These population were phenotyped for the Normalized Difference Vegetation Index (NDVI), Canopy Temperature Depression (CTD), SPAD-meter relative chlorophyll content of the leaves (SPAD) and wilting for QTL mapping. These surrogate traits are related to trait of interest for drought tolerance. NDVI is effective in predicting biomass and yield. Similarly, CTD is associated with transpiration efficiency and carbon dioxide assimilation. Mapping identified 27 minor QTL on eight chromosomes for all physiological characteristics, i.e NDVI, CTD, SPAD and wilting with logarithmic of odds values range from 2.5 to 38.5 and the phenotypic variance explained by these traits ranging from 1.04 to 11.46 %. There were 4 loci on chromosome 2 associated with NDVI in Pop-1 and Pop-3, explaining 1.8 to 10.38% of the phenotypic variation. These genomic regions may be important resources in peanut breeding programs to improve drought tolerance. Further research is needed to increase the marker density in order to fine map the identified QTL and validate markers linked with these regions.

Orientador: Rinaldo Cesar de Paula / Resumo: RESUMO – O eucalipto é a cultura de maior destaque para o setor florestal brasileiro. No entanto, a expansão do setor para áreas com condições climáticas limitantes ao desenvolvimento da cultura e a instabilidade climática atual, são alguns dos fatores que têm comprometido o desenvolvimento desta cultura no país nos últimos anos. Assim, é importante a busca contínua por ferramentas que possibilitem a prognose de crescimento, a seleção de indivíduos e famílias e a análise do comportamento de genótipos de eucalipto frente às variações ambientais de forma cada vez mais acurada. Desta forma, o objetivo geral deste trabalho foi testar o desempenho das Redes Neurais Artificiais (RNA) na modelagem de crescimento de clones de eucalipto, na predição de valores genéticos de indivíduos e famílias, e na seleção quanto à produtividade, estabilidade e adaptabilidade de progênies de Eucalyptus sp. Para a prognose de crescimento foram utilizados dados de 18 clones comerciais de Eucalyptus em diferentes estados do Brasil, e para a estimação de valor genético e análise de produtividade, estabilidade e adaptabilidade foram utilizados dados de testes de progênies de Eucalyptus grandis. Neste trabalho foram testadas diferentes arquiteturas de RNA do tipo múltiplas camadas com o algoritmo de aprendizado de retropropagação do erro e função de ativação do tipo tangente hiperbólica. O modelo desenvolvido para prognose do diâmetro à altura do peito (DAP) de árvores individuais em um local foi capaz de... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: ABSTRACT – Eucalyptus is the most important crop of the most important for the Brazilian forest sector. However, the expansion of the sector to areas with climatic conditions limiting the development of the crop and current climate instability are some of the factors that have compromised the development of this culture in the country in recent years. Thus, it is important to continuously search for tools that allow the prognosis of growth, the selection of individuals and families and the analysis of the behavior of eucalyptus genotypes in the face of environmental changes in an increasingly accurate way. Thus, the general objective of this work was to test the performance of artificial neural networks (ANN) in the modeling of growth of eucalyptus clones, prediction of genetic values of individuals and families, and selection of productivity, stability and adaptability of progenies of Eucalyptus sp. For the prognosis of growth, data from 18 commercial Eucalyptus clones were used in different states of Brazil, and for genetic value estimation and productivity, stability and adaptability analysis data from Eucalyptus grandis progenies were used. In this work, different ANN architectures of the multilayer type were tested with the backpropagation error algorithm and hyperbolic tangent activation function. The model developed for prognosis of the diameter at breast height (DBH) individual trees in one place was able to maintain good accuracy when applied at other sites. The thre... (Complete abstract click electronic access below) / Doutor

Estudar a diversidade genética, a adaptabilidade e estabilidade de genótipos de soja é de extrema importância para os programas de melhoramento genético, visto que a identificação de parentais é prejudicada pela estreita base genética da soja brasileira, além disso, a recomendação de cultivares para as diversas regiões brasileiras constituise em um dos principais desafios do melhoramento. Esta dissertação está subdividida em três capítulos, sendo que no primeiro realizou-se o referencial teórico da soja, importância econômica, melhoramento genético e ferrugem asiática. O segundo capítulo foi desenvolvido com o objetivo de avaliar a divergência genética de genótipos de soja sob infecção natural por ferrugem. O experimento foi realizado na Fazenda Capim Branco da UFU, na safra 2016/17. Utilizaram-se 14 genótipos, sendo 10 linhagens desenvolvidas pelo Programa de Melhoramento Genético de Soja da UFU e 4 cultivares (UFUS 7415, UFUS Riqueza, TMG 801 e BRSGO 7560), em delineamento de blocos casualizados com três repetições. Concluiu-se que existe variabilidade genética para todos os caracteres agronômicos avaliados, com exceção de altura de inserção da primeira vagem e altura de planta na floração. As linhagens UFUS 1117-01, UFUS 1117-07, UFUS 1117-08, UFUS 1117-09, UFUS 1117-10 apresentaram resistência a Phakopsora pachyrhizi e foi identificado que os caracteres de altura de planta na maturidade, número de vagens chochas, número de dias para a maturidade e área abaixo da curva de progresso da doença foram os que mais contribuíram para a divergência genética. Algumas hibridações foram sugeridas objetivando a resistência à ferrugem asiática, em todos os cruzamentos a linhagem UFUS 1117-06 esteve presente. O terceiro capítulo refere-se ao estudo da adaptabilidade e estabilidade produtiva dos 14 genótipos de soja cultivados nas safras 2013/14, 2014/15, 2015/16, 2016/17. Foi possível concluir que a interação genótipos por ambientes é do tipo complexa para a produtividade de grãos. A linhagem UFUS 1117-01 foi identificada como sendo de alta estabilidade produtiva pelos métodos de Eberhart e Russel (1966), Wricke (1965), Additive Main Effects and Multiplicative Interaction (AMMI 1 e AMMI 2), e Centroide. O genótipo UFUS 1117-07 apresentou alta estabilidade pelos métodos Eberhart e Russel (1966), Wricke (1965), Lin e Binns 1988 modificado por Carneiro 1999 e ampla adaptabilidade por Eberhart e Russel e Centroide, já UFUS 1117-09 foi identificado como sendo adaptável a ambientes desfavoráveis por Lin e Binns modificado por Carneiro, AMMI1 e Centroide, enquanto que UFUS 1117-10 apresentou adaptabilidade a ambientes favoráveis pelos métodos AMMI1 e Centroide e alta estabilidade por Eberhart e Russel. / Studying a genetic diversity, adaptability and stability of soybean genotypes are of extreme importance for breeding programs, since the identification of parents is impaired by the narrow genetic base of Brazilian soybean, and a recommendation of cultivars for the different regions is one of the main challenges for improvement. This dissertation is subdivided into three chapters, the first is the theoretical reference of soy, economic importance, genetic breeding and Asian rust. The second chapter was developed with the objective of evaluating the genetic divergence of soybean genotypes under natural rust infection. The experiment was carried out at Fazenda Capim Branco, UFU, in the 2016/17 harvest. A total of 14 genotypes were used, including 10 lines developed by the UFU Soybean Breeding Program and four cultivars (UFUS 7415, UFUS Riqueza, TMG 801 and BRSGO 7560) in a randomized complete block design with three replicates. It was concluded that there is genetic variability for all agronomic traits, except for the height of the first pod and plant height at flowering. The lineages UFUS 1117-01, UFUS 1117-07, UFUS 1117-08, UFUS 1117-09, UFUS 1117-10 presented resistance to Phakopsora pachyrhizi and were identified in components of plant height at maturity, number of pods, number of days to maturity and area under disease progress curve they were the ones that contributed most to a genetic divergence. Hybridizations were suggested aiming the resistance to Asian rust, the strain UFUS 1117-06 was present in all crosses. The third chapter refers to the study of the adaptability and productive stability of the 14 soybean genotypes grown in the 2013/14, 2014/15, 2015/16, 2016/17 seasons. It was possible to conclude that the genotypesenvironments interaction is of a complex type for grain yield. UFUS 1117-01 lineage was identified as being of high stability produced by the methods of Eberhart and Russel (1966), Wricke (1965), Principal additive effects and multiplicative interaction (AMMI 1 and AMMI 2), and Centroid. UFUS 1117-07 genotype showed high stability by the methods Eberhart and Russel (1966), Wricke (1965), Lin and Binns 1988 modified by Carneiro 1999 and wide adaptability by Eberhart and Russel and Centroid. UFUS 1117-09 was identified as being adaptive to unfavorable environments by Lin and Binns modified by Carneiro, AMMI1 and Centroid, while UFUS 1117-10 presented adaptability to environments favorable to AMMI1 and Centroid and high stability by Eberhart and Russel. / Dissertação (Mestrado)