Orientador: Morel de Passos e Carvalho / Banca: Marcelo Andreotti / Banca: Célia Regina Lopes Zimback / Resumo: O arroz é uma das fontes básicas de alimentação da humanidade. No processo de modernização e racionalização da agricultura brasileira, o uso de adubação adequada constitui um fator importante para o aumento da produtividade das culturas, redução dos custos de produção, maior retorno econômico para os produtores e redução do risco de degradação do meio ambiente. Assim, durante o ano agrícola 2009/2010, no município de Selvíria (MS), no Cerrado Brasileiro, foram estudados os atributos do arroz de terras e os atributos químicos de um LATOSSOLO VERMELHO Distroférrico sob sistema plantio direto, irrigado por pivô central. O objetivo foi selecionar entre os atributos pesquisados, aquele com a melhor correlação, linear e espacial, para explicar a variabilidade da produtividade do arroz de terras altas. Foi instalada a malha geoestatística, para a coleta de dados do solo e da planta, com 120 pontos amostrais, numa área de 3,0 ha e declive homogêneo de 0,055 m m-1. Do ponto de vista linear, o número de espiguetas viáveis por panícula apresentou correlação potencial direta com a produtividade de grãos de arroz. Entretanto, do ponto de vista espacial, o teor da matéria orgânica do solo, quando avaliada na camada 0,10 - 0,20 m, apresentou-se como indicador da produtividade de grãos de arroz. Dessa forma, visando-se auxiliar futuros trabalhos voltados à agricultura de precisão, os quais venham a utilizar os mesmos atributos que os do presente, os valores dos alcances da dependência espacial a serem empregados deverão estar compreendidos entre 40,2 e 181,2 metros / Abstract: The rice is one of the basic sources of the humanity's feeding. In the modernization process and rationalization of the Brazilian agriculture, the use of appropriate fertilization constitutes an important factor for the increase of the yield crop, reduction of the production costs, larger economical return for the producers and reduction of the risk of degradation of the environment. Like this, during the agricultural year 2009/2010, in Selvíria County, Mato Grosso do Sul State, in the Brazilian Savannah, they were studied the attributes of the rice uplands and the chemical attributes in a Dystropherric Red Latosol (Typic Acrustox) under no-tillage, irrigated by central pivot. The objective was to select among the researched attributes, that with the best correlation, spatial and linear, to explain upland rice yield variability. The geostatistical grid was installed, to collect the soil and plant data, with 120 sampling points, in an area of 3.0 ha and and homogeneous slope of 0.055 m m-1. Of the linear point of view, the number of viable spikelets per panicle showed direct potential correlation with the yield of grains of rice. However, of the spatial point of view, the organic matter soil, when appraised in the layer 0.10-0.20 m, showed up came as indicator of the yield of grains of rice. Thus, in order to support future researches concern precision agriculture, which uses the same attributes of this research, the values of the range of the spatial dependence to be utilized should be among 40.2 and 181.2 meters / Mestre

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2017-05-05T14:57:53Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Parâmetros genéticos e correlações para caracteres de qualid.pdf: 655495 bytes, checksum: 394a538a094198fedbd0b5c7ec964be4 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-05-10T15:47:22Z (GMT) No. of bitstreams: 2 Parâmetros genéticos e correlações para caracteres de qualid.pdf: 655495 bytes, checksum: 394a538a094198fedbd0b5c7ec964be4 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-05-10T15:47:22Z (GMT). No. of bitstreams: 2 Parâmetros genéticos e correlações para caracteres de qualid.pdf: 655495 bytes, checksum: 394a538a094198fedbd0b5c7ec964be4 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-03-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / A busca incessante por maior produtividade e qualidade dos alimentos é uma das maiores preocupações mundiais. O arroz (Oryza sativa L.) é uma das bases na alimentação e segundo cereal mais produzido no mundo, sendo considerada uma das principais culturas com potencial para combater a fome. Desta forma, os programas de melhoramento desse cereal têm intensificado a busca por genótipos superiores, prioritariamente para produtividade, contudo, atualmente também estão focando neste mesmo nível de prioridade os atributos de qualidade de grãos. Sendo estes atributos decisivos na adoção de uma linhagem melhorada como uma cultivar comercial, pois reflete diretamente no seu valor de mercado e aceitação do consumidor. Neste sentido, o presente trabalho teve por objetivo determinar a adaptabilidade e estabilidade, bem como, estudar as correlações genéticas, dos caracteres de qualidade de grão de cultivares e linhagens elites de arroz irrigado para facilitar as inferências requisitadas pelos melhoristas. Dois ensaios experimentais foram conduzidos em diferentes ambientes, nas safras agrícolas de 2014/15 e 2015/16. O primeiro experimento teve como objetivos avaliar a adaptabilidade e estabilidade de linhagens elites de arroz irrigado em oito ambientes distintos, pelos métodos de MHVG, PRVG e MHPRVG. As linhagens AB11502, AB10501, AB13008, AB13002 e AB13003 apresentaram bom desempenho agronômico, além de adaptabilidade e estabilidade para os caracteres de qualidade de grãos, perante os métodos propostos. O segundo experimento teve o objetivo de evidenciar as correlações genéticas e as associações diretas e indiretas de caracteres agronômicos e atributos de qualidade de grãos, relacionados ao rendimento de grãos inteiros em arroz irrigado pela análise de trilha. A área gessada total, juntamente com a brancura total são os fatores que mais influenciaram no percentual de grãos inteiros, tanto via correlações genotípicas, quanto via efeitos diretos pela análise de trilha, demonstrando assim, potencial para utilização como critérios de seleção indireta para rendimento de grãos inteiros. Cabe ressaltar que ainda há poucos trabalhos na área de genética quantitativa para o caráter de qualidade dos grãos, de maneira que o progresso genético da mesma está apenas no começo. Neste sentido, novas pesquisas devem ser realizadas, visando utilizar cada vez mais, tais ferramentas no processo de seleção. Palavras-chave: Oryza sativa L.; rendimento de engenho; grãos inteiros; / Nowadays, the incessant quest for greater productivity and food quality is one of the world's biggest concerns. Rice (Oryza sativa L.) is one of the bases in human nutrition, being the second most produced cereal in the world, considered one of the main crops with potential to fight hunger. In this way, they are highly important among breeding programs. These factors that intensify the search for superior genotypes, mainly for productivity, however, the attributes of grain quality are also classified at this same level of priority. These attributes are decisive in the adoption of an improved lineage as a commercial cultivar, as it directly reflects its market value and consumer acceptance. In this sense, the objective of the present work was to determine the adaptability and stability, as well as to study the genetic correlations of grain quality traits of cultivars and elite breeding lines of irrigated rice to facilitate the inferences requested by breeders. Two experimental trials were conducted in different environments, in the agricultural crops of 2014/15 and 2015/16. The first experiment had as objectives to evaluate the adaptability and stability for elite breeding lines of irrigated rice in eight different environments, by the methods of MHVG, PRVG and MHPRVG. The lines AB11502, AB10501, AB13008, AB13002 and AB13003 showed good agronomic performance, besides adaptability and stability for grain quality characters, in relation to the proposed methods. The second experiment had the objective of evidencing the genetic correlations and the direct and indirect associations of agronomic traits and grain quality attributes, related to the yield of whole grains in rice irrigated by path analysis. The total chalky area together with the total whiteness were the factors that influenced the percentage of whole grains, both via genotypic correlations and via direct effects through path analysis, thus showing potential for use as indirect selection criteria for yield whole grain. It should be emphasized that there are still few studies in quantitative genetics for the grain quality traits, so that the genetic progress is only at the beginning. In this sense, new research must be carried out, aiming to use these tools more and more in the selection process.

Submitted by Maria Beatriz Vieira (mbeatriz.vieira@gmail.com) on 2017-06-22T12:29:24Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_marcelo_nogueira_do_amaral.pdf: 2321866 bytes, checksum: 813c57b5a855e4f2470433f907cc1a61 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-06-22T20:37:11Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_marcelo_nogueira_do_amaral.pdf: 2321866 bytes, checksum: 813c57b5a855e4f2470433f907cc1a61 (MD5) / Made available in DSpace on 2017-06-22T20:37:11Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_marcelo_nogueira_do_amaral.pdf: 2321866 bytes, checksum: 813c57b5a855e4f2470433f907cc1a61 (MD5) Previous issue date: 2015-03-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / O arroz (Oryza sativa L.) é o segundo cereal mais cultivado no mundo, sendo o Brasil o 9º maior produtor. Apesar dos bons níveis de produtividade, acredita-se que estes números sejam insuficientes para suprir o requerimento populacional no mundo, sendo necessário um aumento na produção. Entretanto, diversos estresses abióticos, como salinidade, toxidez por ferro e baixa temperatura, limitam a produtividade do arroz mundialmente. A resposta das plantas às condições estressantes é um fenômeno complexo, envolvendo alterações morfológicas, fisiológicas, bioquímicas e moleculares. Assim, o conhecimento do transcriptoma e análise fotossintética de plantas de arroz submetidas a estes estresses, pode auxiliar a elucidar quais vias metabólicas são alteradas e quais são as principais respostas bioquímicas e fisiológicas das plantas em tais condições. Desta forma, o objetivo desse trabalho foi analisar os genes diferencialmente expressos (DEGs), através da metodologia de RNA-Seq e quantificar as trocas gasosas em folhas de arroz (cv. BRS Querência), no estádio V3, submetidas aos estresses por frio, ferro e sal durante o período de 24 horas. Um intervalo entre 41 - 51 milhões de reads foram submetidas ao alinhamento, sendo que deste total um intervalo entre 88,47 - 89,21% foram mapeadas no genoma de referência. Foi observado 5.506 genes diferencialmente expressos para o estresse por frio, 1.808 para o sal e 630 para o ferro, sendo que 330 DEGs foram comuns aos três estresses. A anotação funcional através do software MapMan demonstrou que o estresse por frio promoveu maiores alterações no metabolismo em geral. O estresse salino apresentou uma rede de interação de termos de Ontologia Gênica (GOs) sobre-representados mais complexa que os demais estresses. Nos parâmetros de trocas gasosas, a taxa assimilatória liquida foi a única que apresentou diferença significativa, com o estresse por frio apresentando a menor média. A partir dos resultados obtidos foi possível concluir que o estresse por baixa temperatura apresenta um maior número de genes diferencialmente expressos e que há uma maior relação entre o estresse salino e por ferro. Além disso, o estresse por frio é o que afeta mais drasticamente a fotossíntese, tanto em nível molecular quanto fisiológico, e apesar de reduções na taxa assimilatória liquida, a cultivar BRS Querência demonstrou menores alterações nos estresses salino e por excesso de ferro. / Rice (Oryza sativa L.) is the second most cultivated cereal in the world; Brazil is the ninth biggest producer. Despite the high levels of productivity, it is believed that these numbers are insufficient to meet the population requirement in the world, demanding an increase in its production. However, various abiotic stresses, such as salinity, toxicity by iron and low temperature, limit the productivity of rice worldwide. The response of plants to stressful conditions is a complex phenomenon involving morphological, physiological, biochemical and molecular changes. Thus, the knowledge of the transcriptome and photosynthetic analysis of rice plants subjected to these stresses can help to elucidate which metabolic pathways are changed and what are the main biochemical and physiological responses of plants under such conditions. Thus, the objective of this study was to analyze the differentially expressed genes (DEGs), through the methodology of RNA-Seq and quantify gas exchanges in rice leaves (cv. BRS Querência) in V3 stage, under cold, iron and salt stress during 24 hours. A range from 41 to 51 million reads was submitted to alignment, in which a range from 88.47 to 89.21% has been mapped in the reference genome. 5,506 differentially expressed genes under cold stress were observed, as well as, 1,808 for salt and 630 for iron stress; 330 of them were similar to the three DEGs stresses. Functional annotation by MapMan software showed that, usually, cold stress promoted major changes in the metabolism. The saline stress presented a network of interaction of Gene Ontology terms (GOs) over-represented are more complex than the other stresses. In the parameters of gas exchange, the net assimilation rate was the only one significant difference, with stress by cold presenting the lowest average. From the results obtained it was possible to conclude that the low temperature stress has a greater number of differentially expressed genes and that there is a greater relationship between salt and iron stress. In addition, the cold stress is affecting more drastically photosynthesis, either in molecular-level and physiological, and despite reductions in net assimilation rate, BRS Querência showed minor changes in the salt stress and excess iron.

Submitted by Maria Beatriz Vieira (mbeatriz.vieira@gmail.com) on 2017-06-23T12:49:03Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese_isabel_lopes_vighi.pdf: 2167536 bytes, checksum: ac573c14d5ef3a4795a4bf594d60bd85 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-06-23T22:08:52Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese_isabel_lopes_vighi.pdf: 2167536 bytes, checksum: ac573c14d5ef3a4795a4bf594d60bd85 (MD5) / Made available in DSpace on 2017-06-23T22:08:52Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese_isabel_lopes_vighi.pdf: 2167536 bytes, checksum: ac573c14d5ef3a4795a4bf594d60bd85 (MD5) Previous issue date: 2016-03-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / O arroz (Oryza sativa L.) é o segundo cereal mais cultivado no mundo, sendo o Brasil o 9º maior produtor. No entanto sua produção é severamente influenciada por condições ambientais adversas, dentre as quais se destaca a salinidade e baixas temperaturas. O objetivo deste estudo foi avaliar respostas, bioquímicas e moleculares desencadeadas pela salinidade e por baixas temperaturas em plantas de arroz, com respostas contrastantes. Para atingir este objetivo foram realizados três estudos: No primeiro, foram quantificados os teores do ânion Superóxido (O2•−), Peróxido de hidrogênio (H2O2), Peroxidação lipídica (MDA), atividade enzimática e expressão gênica diferencial das isoformas das enzimas Superóxido dismutase (SOD), Catalase (CAT), Ascorbato peroxidase APX e Glutationa reduzida (GR) em genótipos com tolerância contrastante ao sal. Para o genótipo sensível (BRS Pampa), ocorreu aumento na atividade enzimática da SOD, CAT, APX e diminuição nos níveis de MDA. No genótipo tolerante (BRS Bojuru), também foi observado aumento da atividade das enzimas SOD e CAT, porém diminuição nos níveis de MDA. A regulação positiva das diferentes isoformas da SOD, CAT e APX demonstrou a sua contribuição para o aumento na atividade da enzima. No segundo estudo, foram quantificados os teores de H2O2, MDA, atividade enzimática e expressão gênica da CAT, bem como análise do promotor e cis elementos, nos mesmos dois genótipos contrastantes frente ao estresse por salinidade e baixa temperatura. O genótipo BRS Pampa (sensível) foi o que mostrou maior proteção contra danos oxidativos frente ao estresse por frio, bem como aumento na atividade da CAT e do número de transcritos das isoformas OSCATA e OSCATB. No terceiro estudo, avaliou-se o metabolismo da prolina em plantas de arroz, através do padrão de expressão dos genes envolvidos na biossíntese e catabolismo desse aminoácido e verificou-se a correlação com o conteúdo de prolina produzido em condições de estresse por salinidade e baixa temperatura. O conteúdo de prolina foi maior no genótipo BRS Bojuru (tolerante) frente às duas condições de estresse testadas. Sob estresse salino, os níveis de transcritos dos genes de biossíntese estão mais correlacionados com o conteúdo de prolina no genótipo tolerante, enquanto que em condições de baixa temperatura a correlação é maior no genótipo sensível. Os resultados obtidos permitem concluir que, sob estresse salino e por baixa temperatura, as plantas de arroz apresentam respostas diferenciais a nível bioquímico e molecular, sendo estas respostas dependentes do tempo, intensidade do estresse e composição genética dos genótipos. / Rice (Oryza sativa L.) is the second most cultivated cereal in the world, and Brazil is the 9th largest producer. However production is severely affected by adverse environmental conditions, among which the mains ones are the salinity and low temperatures. The aim of this study was to evaluate responses, biochemical and molecular triggered by salinity and low temperatures in rice plants with contrasting response. To achieve this goal there were three studies: In the first one, the anion content superoxide (O2•-) were quantified, hydrogen peroxide (H2O2), lipid peroxidation (MDA), enzyme activity and differential gene expression of isoforms of the enzyme superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase APX and reduced glutathione (GR) in genotypes with contrasting tolerance to salt. For the sensitive genotype (BRS Pampa), there was an increase in the enzymatic activity of SOD, CAT, APX and a decrease in MDA levels. In tolerant genotype (BRS Bojuru) was also observed an increased activity of enzymes SOD and CAT, but a decrease in MDA levels. The upregulation of the different isoforms of SOD, CAT and APX has demonstrated its contribution to the increase in the enzyme activity. In the second study, H2O2 levels were quantified, MDA, enzyme activity and gene expression of CAT, and promoter analysis and cis-elements, the same two contrasting genotypes against salinity stress and low temperature. The BRS Pampa genotype (sensitive) was the one that showed greater protection against oxidative damage compared to the stress by cold, as well as an increase in CAT activity and the number of transcripts OSCATA and OSCATB isoforms. In the third study evaluated the metabolism of proline in rice plants through the expression pattern of genes involved in biosynthesis and catabolism of amino-acid and was found to correlate with the proline content produced under stress by salinity and low temperature. The proline content was higher in BRS Bojuru genotype (tolerant) against the two tested stress conditions. Under salt stress, the biosynthesis gene transcript levels are more correlated with the proline content in tolerant genotype, whereas in low temperature conditions the correlation is highest in sensitive genotype. The results showed that under salt stress and low temperature, the rice plants have differential responses to biochemical and molecular level, which are dependent responses of time, stress intensity and genetic makeup of the genotypes.

Orientador: Orivaldo Arf / Banca: Orivaldo Arf / Banca: Maria Aparecida Anselmo Tarsitano / Banca: Helder Barbosa Paulino / Resumo: O trabalho foi conduzido no ano agrícola de 2005/06, no município de Selvíria, Estado do Mato Grosso do Sul e teve como objetivo avaliar o comportamento do arroz de terras altas irrigado por aspersão em função do manejo do solo e da adubação nitrogenada em cobertura. O delineamento experimental utilizado foi o de blocos ao acaso disposto em um esquema fatorial 3 x 2 x 7, totalizando 42 tratamentos constituídos pela combinação de três modalidades de preparo do solo (grade pesada + grade niveladora, escarificador + grade niveladora e plantio direto), duas fontes de adubos nitrogenados, na dose de 90 kg ha-1 (Uréia e um sulfonitrato de amônio com inibidor de nitrificação = Entec) e da aplicação de nitrogênio em diferentes épocas de desenvolvimento da cultura do arroz de terras altas, com quatro repetições. Os manejos do solo utilizados influenciaram a altura de plantas, grau de acamamento, total de grãos por panícula, grãos cheios e chochos por panícula e produtividade de grãos, onde o manejo com grade pesada apresentou melhores resultados. O manejo da adubação influenciou apenas a produtividade de grãos. O uso do Entec proporcionou um maior número de grãos cheios e menor número de grãos chochos em relação à uréia / Abstract: The research was conducted in 2005/06, in Selvíria, Mato Grosso do Sul State, and had the objective of evaluating the development of upland rice irrigated by aspersion considering the management of soil and top-dress nitrogenous fertilization as to grain productivity and quality. The experimental design was a randomized in a factorial scheme of 3 x 2 x 7, totalizing 42 treatments as a result of a combination of three types of soil management (heavy disk + leveling disk; disk plow + leveling disk; no-till), two nitrogenous seasoning sources, urea and sulfatenitrate ammonium with inhibitor of nitrification (Entec) and 90 kg ha-1, of applied at different growth stages on upland rice crop under sprinkler irrigation, with four repetitions. The soil management influenced the height of plants, degree of lodging rate, total of full and empty grainsser panicle and productivity of grains. The soil management with disk + leveling disk presented better resulted. Handling of the fertilization influenced only the productivity of grains. The use of Entec provided a bigger number of full grains and less empty grains in relation to use of urea / Mestre

L'objectif scientifique de mon travail de recherche et d'encadrement d'étudiants a principalement concerné la détermination des bases génétiques de la résistance à la sécheresse du riz. Une partie de ces travaux ont été menés à l'Institut International de Recherche sur le Riz aux Philippines, dans le cadre d'un programme de sélection du riz pluvial pour l'Asie du Sud et du Sud-Est. Le riz pluvial ne dépend que la pluviométrie pour son alimentation hydrique et souffre donc de déficits hydriques fréquents. La nature des sécheresses rencontrées dans les environnements cibles m'ont conduite à travailler plus particulièrement sur la morphologie du système racinaire et sur l'ajustement osmotique. L'approche choisie a été celle de la génétique moléculaire. Les travaux conduits ont permis des progrès dans la compréhension du déterminisme génétique de ces caractères et la localisation de QTL d'intérêt dans des populations de cartographie classique, puis des populations de back-cross avancés, plus adaptées à un programme de sélection. Des lignées quasi isogéniques introgressées avec des QTLs de profondeur racinaire ont été produites par sélection assistée par marqueurs et utilisées pour valider l'existence et l'effet des QTLs. <br /> Mon projet de recherche actuel conduit à Montpellier dans l'UMR "Développement et Amélioration des Plantes" se situe dans la continuité des travaux précédents. Il consiste à relier les nombreux QTL de morphologie racinaire identifiés à ce jour chez le riz aux gènes sous jacents, puis à analyser la variabilité allélique de ces gènes dans différents fonds génétiques. Plusieurs approches complémentaires seront utilisées pour réaliser la cartographie fine des QTLs. La large gamme de données disponibles va d'abord être utilisée pour affiner la position des QTLs par une approche statistique de méta-analyse. L'approche d'étude d'association a également été retenue ce qui suppose, en préalable, de clarifier l'étendue du déséquilibre de liaison chez le riz. Des approches au niveau du génome entier seront suivies d'approches ciblées sur des gènes candidats, en ayant largement recours aux données de séquençage total du génome de 2 variétés de riz et de séquençage partiel de 20 autres. Enfin, en utilisant les lignées quasi-isogéniques produites à l'IRRI, le clonage d'un QTL de profondeur racinaire a été entrepris.<br /> L'intégration de ces approches de génétique directe avec les approches complémentaires de génétique inverse utilisées par d'autres personne de l'équipe "Développement et adaptation du riz" se fera autour des gènes dont la fonction aura été validée. La combinaison des allèles les plus adaptés aux environnements cibles dans des variétés d'élite constituera le but ultime de mon travail.

Rice grows in saturated soil water condition and its requirement for water is highest amongst other cereal crops. In India, the southwest monsoon wind regime brings rainfall that provides a favourable environment for rice cultivation. Thus, there is significant dependency ofrice production on the southwest monsoon rainfall. Being a crop that grows across diverse climatic regions in India ranging from the humid to semi-arid, it offers possibility to explore therelationship between stable isotopic compositions in the grain organic matter with the climaticfactors relevant for its growth. In this thesis, we measured the isotopic compositions of oxygen, hydrogen and carbon of several rice genotypes that were cultivated during the southwest monsoon in diverse climatic regions across the Indian landmass. These isotopic values were then compared with the seasonalaverage values of climate factors such as relative humidity and temperature. Together with thiswe also studied the dependency of the oxygen isotope composition of the grain OM (δ18OOM) onthat of the source water (δ18OSW). Upon removal of δ18OSW effect from δ18OOM, we obtained astrong and significant relationship between the 18O enrichment in grain organic matter (definedas 18OOM) with relative humidity. The gradient recorded was 0.45‰ shift in 18OOM with 1%change in the relative humidity level. This relationship can potentially be used to estimate thepast variations in relative humidity (and by extension, can provide a measure of monsoon rainfallvariations). We further validated this relationship based on experiments carried out in aglasshouse where all the physical factors were well-monitored. Together with this, carbonisotopic composition measured in the rice grain organic matter were used to infer the water useefficiency of rice grown in different climatic settings. The stable isotope approach was furtherimplemented for studying the archaeological rice grains recovered from archaeological sites. Analysis of carbon isotopic composition of archaeological rice grains from seven archaeologicalsites (Balu, Kanmer, Ojiyana, Lahuradewa, JognaKhera, Hulas and Kunal), belonging to theHarappan civilization and other contemporary cultures provided a new suit of data on quantitativeestimate of the hydroclimatic condition (specifically relative humidity) and water availabilityduring the existence of this civilization.

Rice grows in saturated soil water condition and its requirement for water is highest amongst other cereal crops. In India, the southwest monsoon wind regime brings rainfall that provides a favourable environment for rice cultivation. Thus, there is significant dependency ofrice production on the southwest monsoon rainfall. Being a crop that grows across diverse climatic regions in India ranging from the humid to semi-arid, it offers possibility to explore therelationship between stable isotopic compositions in the grain organic matter with the climaticfactors relevant for its growth. In this thesis, we measured the isotopic compositions of oxygen, hydrogen and carbon of several rice genotypes that were cultivated during the southwest monsoon in diverse climatic regions across the Indian landmass. These isotopic values were then compared with the seasonalaverage values of climate factors such as relative humidity and temperature. Together with thiswe also studied the dependency of the oxygen isotope composition of the grain OM (δ18OOM) onthat of the source water (δ18OSW). Upon removal of δ18OSW effect from δ18OOM, we obtained astrong and significant relationship between the 18O enrichment in grain organic matter (definedas 18OOM) with relative humidity. The gradient recorded was 0.45‰ shift in 18OOM with 1%change in the relative humidity level. This relationship can potentially be used to estimate thepast variations in relative humidity (and by extension, can provide a measure of monsoon rainfallvariations). We further validated this relationship based on experiments carried out in aglasshouse where all the physical factors were well-monitored. Together with this, carbonisotopic composition measured in the rice grain organic matter were used to infer the water useefficiency of rice grown in different climatic settings. The stable isotope approach was furtherimplemented for studying the archaeological rice grains recovered from archaeological sites. Analysis of carbon isotopic composition of archaeological rice grains from seven archaeologicalsites (Balu, Kanmer, Ojiyana, Lahuradewa, JognaKhera, Hulas and Kunal), belonging to theHarappan civilization and other contemporary cultures provided a new suit of data on quantitativeestimate of the hydroclimatic condition (specifically relative humidity) and water availabilityduring the existence of this civilization

Rice grows in saturated soil water condition and its requirement for water is highest amongst other cereal crops. In India, the southwest monsoon wind regime brings rainfall that provides a favourable environment for rice cultivation. Thus, there is significant dependency ofrice production on the southwest monsoon rainfall. Being a crop that grows across diverse climatic regions in India ranging from the humid to semi-arid, it offers possibility to explore therelationship between stable isotopic compositions in the grain organic matter with the climaticfactors relevant for its growth. In this thesis, we measured the isotopic compositions of oxygen, hydrogen and carbon of several rice genotypes that were cultivated during the southwest monsoon in diverse climatic regions across the Indian landmass. These isotopic values were then compared with the seasonalaverage values of climate factors such as relative humidity and temperature. Together with thiswe also studied the dependency of the oxygen isotope composition of the grain OM (δ18OOM) onthat of the source water (δ18OSW). Upon removal of δ18OSW effect from δ18OOM, we obtained astrong and significant relationship between the 18O enrichment in grain organic matter (definedas 18OOM) with relative humidity. The gradient recorded was 0.45‰ shift in 18OOM with 1%change in the relative humidity level. This relationship can potentially be used to estimate thepast variations in relative humidity (and by extension, can provide a measure of monsoon rainfallvariations). We further validated this relationship based on experiments carried out in aglasshouse where all the physical factors were well-monitored. Together with this, carbonisotopic composition measured in the rice grain organic matter were used to infer the water useefficiency of rice grown in different climatic settings. The stable isotope approach was furtherimplemented for studying the archaeological rice grains recovered from archaeological sites. Analysis of carbon isotopic composition of archaeological rice grains from seven archaeologicalsites (Balu, Kanmer, Ojiyana, Lahuradewa, JognaKhera, Hulas and Kunal), belonging to theHarappan civilization and other contemporary cultures provided a new suit of data on quantitativeestimate of the hydroclimatic condition (specifically relative humidity) and water availabilityduring the existence of this civilization.

The objective of this research was to investigate the occurrence of mycoflora in rice plants and rice seeds in South Africa and their negative impact. A total of six species of Fusarium were isolated from diseased rice plants and rice seeds and identified as F. anthophilum, F. chlamydosporum, F. compactum, F. equiseti, F. fujikuroi and F. semitectum. In the translation elongation factor data set, Fusarium equiseti isolates grouped together within the F. incarnatum - equiseti Species Complex (FIESC). The isolates from rice clustered together in a single clade with the F. equiseti and F. incarnatum isolates forming two separate sub-clades.The isolates of F. equiseti present a new phylogenetically distinct species in FIESC. In the pathogenicity tests, isolates of both F. anthophilum and F. fujikuroi caused bakanae disease to rice plants. Fifty four rice cultivars and lines were tested by the standardized test tube inoculation method for resistance and susceptibility against bakanae isolate of F. anthophilum and the bakanae isolate of F. fujikuroi. None of the rice cultivars and lines was found to be resistant to bakanae isolates of Fusarium spp. The fungicide, benomyl was found to be most effective as a seed treatment for controlling bakanae disease of rice due to isolates of both F. anthophilum and F. fujikuroi. Thiram was found to be the least effective fungicide for controlling bakanae disease of rice caused by isolates of both the Fusarium spp. Apart from Fusarium species, other fungi that were also isolated from diseased rice plants and rice seeds were identified as Alternaria alternata, Alternaria longipes, Cochliobolus miyabeanus, Nigrospora sphaerica, Phoma eupyrena, Phoma jolyana, Phoma sorghina and Pithomyces sp. In mycotoxin tests, the isolates of both F. anthophilum and F. fujikuroi produced moniliformin. None of the isolates of F. anthophilum and F. fujikuroi produced fumonisins. This research is important as it identifies many fungal species in rice plants and seeds in South Africa for the first time. Currently, there is very little literature that makes reference to such findings under South African conditions. In addition, this investigation unravels previously unknown information on the resistance of rice to bakanese disease. Finally, information is provided on the effectiveness of commonly used fungicides (benomyl and thiram) to control rice diseases. This knowledge is crucial information that is useful to plant pathologists, the farming community and the scientists that are involved in strategies of fighting or reducing rice diseases so as to help contribute to food security. / Environmental Sciences / D. Phil. (Environmental Science)