Abiotic stress is highly detrimental to crop productivity worldwide. Research is key to meeting the challenges of modern agriculture in a sustainable and positive fashion. This thesis contributes to our understanding of plant stress responses by examining two molecular aspects of abiotic stress. The first part of the work focused on the Unfolded Protein Response (UPR), a general stress response mechanism triggered by the accumulation of unfolded or misfolded proteins in the endoplasmic reticulum. The study was conducted with the model plant Arabidopsis and shed new light on key players in the pathway. An unconventional alternative splicing mechanism, similar to the one identified in other higher eukaryotes, was found to parallel the activation of an ER-resident chaperone. The data suggest that this event is important to alleviate cellular stress in response to adverse environmental conditions such as heat. Further understanding of this pathway will help to develop a more complete view of the mechanisms involved in this response. The second part of the work investigated the interaction between nitrogen limitation and drought at the transcriptional level. A genome-wide transcript profiling experiment was performed to provide a comprehensive view of the response to nitrogen and water limitation in corn. The main finding was the demonstration of a clear synergistic effect between both stresses, an effect that was unexpectedly as important as either stress applied alone. This study adds to our current knowledge of abiotic stress response in plants and should provide the groundwork necessary to build future strategies for crop enhancement.

Thesis (MSc (Plant Biotechnology))--University of Stellenbosch, 2010. / ABSTRACT: Nitric Oxide (NO) is an essential bioregulatory molecule in plant growth, development, and tolerance against biotic and abiotic stresses. In legume root nodules, abiotic stresses impose restraint on metabolic capacity of bacteria and cause oxidative damage to cellular macromolecules, leading to inhibition of nitrogenase activity. In this study, the primary aim was to determine the influence of NO signaling on cysteine protease activity in soybean (Glycine. max [L] Merr) root nodules. Intact plants were treated with a NO donor, diethylenetriamine/nitric oxide adjunct (DETA/NO), 8-(4-chlorophenylthio)-[CPT]- cGMP, sorbitol and sodium chloride (NaCl). The root nodule cysteine protease activity was measured using the chromogenic substrate N-benzoil-L-p-nitroanilide (L-BAPNA). The results demonstrated NO as acting both as a protection against programmed cell death (PCD) at low exogenously applied NO concentrations, or as inducing PCD through regulating the cysteine proteases activity in root nodules when NO is applied at elevated concentrations. In the root nodules, the activity of cysteine protease is regulated either through cyclic guanosine monophosphate (cGMP)-dependent during abiotic stress or cGMP-independent pathways during normal root nodule development. The purpose of this research was to highlight the importance of NO in cell signaling and cysteine protease activity in legume root nodules. We also focused on the effect of abiotic stress on two maize genotypes as well as the influence of abiotic stress on cysteine protease activity in the abiotic stress-sensitive maize genotype than the tolerant genotype. The study suggests that cysteine protease activity can be used as early screen to identify abiotic stress-sensitive/tolerant maize genotype upon exposure to abiotic stress. / AFRIKAANSE OPSOMMING: Geen Afrikaanse opsomming beskikbaar. / National Research Foundation

FARIAS, Gabriel Castro. Biometria e respostas fisiológicas de feijão-de-corda inoculado com fungos endofíticos dark septate sob estresse salino. 2014. 55 f. Dissertação (Mestrado em engenharia agrícola)- Universidade Federal do Ceará, Fortaleza-CE, 2014. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-06-23T17:48:04Z No. of bitstreams: 1 2014_dis_gcfarias.pdf: 713863 bytes, checksum: 7be0252f35e54d5ad3dde924985c12a7 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-07-21T20:14:36Z (GMT) No. of bitstreams: 1 2014_dis_gcfarias.pdf: 713863 bytes, checksum: 7be0252f35e54d5ad3dde924985c12a7 (MD5) / Made available in DSpace on 2016-07-21T20:14:36Z (GMT). No. of bitstreams: 1 2014_dis_gcfarias.pdf: 713863 bytes, checksum: 7be0252f35e54d5ad3dde924985c12a7 (MD5) Previous issue date: 2014 / With the increasing of areas degraded by soil salinization process, is necessary to increase of agricultural investments to be able to reach a production acceptable. In order to reduce such inputs, studies of microorganisms involved in the production process are becoming more constant. The objective of this study was to evaluate the associations between endophytic fungi Dark Septate and cowpea plants when irrigated with water of different salinities, analyzing biometrics, gas exchange, nutrient content and accumulation of organic solutes in the leaves. Cowpea plants were grow in containers of five liters under greenhouse conditions and subjected to four different electrical conductivity of irrigations water (1.2; 2.2; 3.6; 5.0 dS m-1). Were used for the inoculation strains B’2 and 21W and treatments were as follows: F1 – plants that were not inoculated; F2 – plants inoculated with strains 21W and F3 – plants inoculated with strain B’2. during the experiment was measured gas exchange and at the end of the experiment the plant were collected and determinate the leaf area, shoot dry mass, root dry mass, concentration of the foliar nutrients and organic solutes, and was made the determination colonization of roots by the fungus. The salinity caused significant reductions in biomass, leaf area and leaf gas exchange, however, the presence of the endophytic fungi provided a large tolerance to the adverse effects of salinity. There was a larger accumulation of calcium, sodium, clore and phosphorus in cowpea leaves with increasing salinity and decrease in the leaves of nitrogen and potassium. The presence of the fungus in the plant provided a foliar phosphorus and nitrogen. / Com o crescimento das áreas degradadas pelo processo de salinização dos solos se faz necessário o aumento do uso de insumos para que seja possível atingir uma produção aceitável. Visando a redução de tais insumos, estudos sobre microrganismos envolvidos no processo produtivo são cada vez mais constantes. O objetivo deste trabalho foi avaliar a resposta das associações entre fungos endofíticos Dark Septate e plantas de feijão-de-corda quando irrigado com águas de diferentes salinidades, analisando-se a biometria, troca gasosas, teores foliares de nutrientes e o acúmulo de solutos orgânicos nas folhas. As plantas de feijãode-corda foram cultivadas em vasos de 5 litros, sob condições de casa de vegetação e submetidas a quatro diferentes condutividades elétricas da água de irrigação (1,2; 2,2; 3,6 e 5,0 dS m-1). Para a inoculação foram utilizados as linhagens B’2 e 21W e os tratamentos foram os seguintes: F1 – plantas que não foram inoculadas; F2 – plantas inoculadas com a linhagem 21W e F3 – plantas inoculadas com a linhagem B'2. Durante a condução do experimento mediu-se as trocas gasosas e ao final do experimento as plantas foram coletadas e determinou-se a sua área foliar, massa seca da parte aérea, massa seca das raízes teores de nutrientes e solutos orgânicos foliares, bem como foi feita a determinação de colonização nas raízes pelo fungo. A salinidade provocou reduções significativas na biomassa, área foliar e trocas gasosas, contudo, a presença do fungo endofítico proporcionou uma maior tolerância aos efeitos negativos da salinidade. Houve um maior acúmulo de cálcio, sódio, cloro e fósforo em folhas de feijão-de-corda com o aumento da salinidade e uma diminuição dos teores de nitrogênio e potássio. A presença do fungo na planta proporcionou maior teor foliar de fósforo e nitrogênio.

Invasive species are cited as a major threat to native community composition and biodiversity throughout the world. Some recent studies have focused on whether invasive species are the drivers or passengers of change in degraded systems. A strongly-interactive community is supposed to resist invasion by all but the most strong invasive competitors (`drivers') which can establish there without the aid of disturbance and actively reduce the abundance of natives. A weakly-interactive community, impaired by some anthropogenic disruption, is invasible by weaker exotics which are merely `passengers' of the habitat degradation that is more constraining to natives. Though competitive and disturbance-adapted species fit into this model, there is no correlate for species with superior toleration of stress. Systems with high degrees of natural abiotic stress are weakly-interactive and as a result may be invasible by an exotic `tolerator' in the same way that anthropogenically-weak systems are invasible by passengers. Dolomite prairie, differentiated from typic tallgrass prairie by its shallow soils, represents a relatively stressful system. A study of its plant community composition and relationships to environmental variables was done to get a better understanding of the natural abiotic drivers of composition. Compositional patterns were most closely associated with the soil depth gradient. Exotic Poa species were by far the most frequent invaders, a finding more typical of Great Lakes alvars than of typic tallgrass prairie of which the dolomite prairie is a subset. I hypothesized that Poa species dominated dolomite prairie via the tolerator model. In a series of removal treatments, I determined that Poa is neither a driver nor a tolerator, but a passenger of environmental degradation. My results suggest that historic anthropogenic degradation rather than specific competitive ability is a common explanation for exotic dominance on the landscape today. More empirical work needs to be conducted in other stressful (particularly relatively undisturbed) systems to further investigate the tolerator model.

Um grande empecilho para a manutenção e estabilidade da produção nacional de soja reside na suscetibilidade dos diferentes genótipos aos estresses ambientais. Tendo em vista a importância social e econômica da leguminosa e os efeitos extremamente danosos dos estresses abióticos sobre a agricultura, faz-se necessário maior conhecimento acerca das interações entre os estímulos estressores e as respostas da planta. A seca é considerada o principal fator limitante na produtividade agrícola. Sendo assim, a identificação e caracterização de genes responsivos a essa condição é um passo inicial na compreensão das respostas adaptativas ao déficit hídrico. Os genes Asr (ABA, Stress and Ripening) são induzidos por estresse e ácido abscísico (ABA) e seus níveis de expressão são rapidamente aumentados em resposta à salinidade e seca. Nesse estudo os genes da família Asr de soja foram clonados. Estas proteínas são hidrofílicas e ricas nos aminoácidos Ala, His, Glu e Lis, apresentando homologia com ASRs de outras plantas, como atestado nas análises de múltiplos alinhamentos. O perfil de expressão foi avaliado através de RT-qPCR em tempo real e revelou que Asr1 tem um distinto padrão de indução no nível de transcritos em folha sob tratamento com ABA, sal e seca, enquanto Asr3 apresenta padrão distinto de indução na expressão em raiz, sob tratamento com ABA e seca. Além disto, foram construídos vetores para a superexpressão e localização subcelular das proteínas ASR1, ASR2 e ASR3 em plantas. Plantas de Arabidopsis thaliana foram submetidas a um protocolo de transformação genética mediada por Agrobacterium. / One of the major obstacles to maintain the stability of the national production of soybean (Glycine max) lies on the susceptibility of different genotypes to abiotic stress. In view of the social and economic importance of soybean and due to the extremely harmful effects of stress in agriculture, detailed knowledge of the interaction between these stresses and plant response to environmental stimuli is necessary. Drought is considered the main abiotic limitation factor for agricultural productivity. Identification and characterization of responsive genes to this condition is an initial step in understanding the adaptive responses to drought. The Asr (ABA, Stress and Ripening) genes are induced by stress and abscisic acid (ABA) in plants, and their expression levels are quickly increased in response to salinity and drought. In this study Asr genes from Glycine max were cloned. These proteins were found to be hydrophilic and rich in amino acids Ala, His, Glu and Lys, showing homology with those of other plant Asr genes via multiple alignment analysis. RT-qPCR analyses revealed that Asr1 had a distinct up-regulated transcript pattern in leaf under ABA, NaCl and drought treatments, while Asr3 had a distinct up-regulated transcript pattern in root under ABA and drought treatments. Besides, vectors for ASR1, ASR2 and ASR3 proteins overexpression and subcellular localization in plants were constructed. Arabidopsis thaliana plants were submitted to an Agrobacterium-mediated transformation procedure.

Made available in DSpace on 2014-06-11T19:32:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-09Bitstream added on 2014-06-13T19:02:46Z : No. of bitstreams: 1 dedemo_gc_dr_jabo.pdf: 863587 bytes, checksum: b47ae11ff9b870e9b2143acb6e76251b (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A cana-de-açúcar tem adquirido crescente importância no cenário mundial, não somente pela produção do açúcar, mas devido ao grande potencial como cultura bioenergética, sendo utilizada na produção do etanol, uma fonte energética alternativa, ecologicamente limpa e renovável e como co-geradora de energia elétrica através da queima do bagaço. O Brasil destaca-se mundialmente como o maior produtor da cultura e exportador de açúcar e etanol. Porém, esta cultura está sujeita a diferentes estresses ambientais, dentre os quais, a disponibilidade de água representa o principal fator que influencia o crescimento e o desenvolvimento vegetal e, conseqüentemente, a produtividade. Dessa forma, para a identificação dos possíveis genes envolvidos nas respostas de tolerância à seca em cana-de-açúcar, realizou-se, por meio da técnica de cDNA-AFLP, a análise comparativa do perfil de transcritos de duas cultivares tolerantes, SP83-5073 e RB867515 com o perfil de expressão da cultivar sensível à seca, SP86-155, quando submetidas a suspensão da rega por 1, 3, 5 e 10 dias. Com 14 combinações de primers seletivos EcoRI/MseI, foram detectados no gel de poliacrilamida, 1.316 fragmentos derivados de transcritos (FDTs) que foram diferencialmente expressos entre as cultivares tolerantes e a sensível, submetidas ao estresse hídrico (1, 3, 5 e 10 dias). Destes, 630 FDTs foram identificados na cultivar SP83-5073 e 686 FDTs na cultivar RB867515. A análise comparativa do perfil de expressão associado ao genótipo da cana-de-açúcar revelou fragmentos de transcritos similares a genes envolvidos em eventos moleculares relacionados às respostas das plantas a diferentes estresses, inclusive ao causado pela seca. Estes genes atuam na sinalização hormonal, regulação da transcrição gênica, senescência, transposição de DNA... / The sugarcane has increased importance in the world not only for sugar production, but also due to the great potential as a generator energy because ethanol production, it is a renewable, alternative energy source, ecologically clean and as energy cogeneration through burning of bagasse. Brazil is the world’s largest crop producer and exporter of sugar and ethanol. However, this crop is exposed to different kinds of stress, among which; the availability of water is noticeable as the main factor that negatively influences the vegetable growth and, therefore, the productivity. In order to identify the possible genes involved in the responses to drought tolerance in sugarcane crops, the comparative analysis of transcripts profile from two tolerant cultivars, SP83-5073, RB867515 and the sensitive cultivar SP86-5073, after has been submitted to the interruption of irrigation for 1, 3, 5 and 10 days were performed using the cDNA-AFLP technique. With 14 combinations of EcoRI/MseI selective primers, there was detected on a polyacrylamide gel, 1,316 transcript-derived fragments (TDFs) differently expressed between tolerant and sensitive cultivars submitted to water deficit (1, 3, 5 and 10 days). From these, 630 TDFs were identified on the cultivar SP83-5073 and 686 TDFs corresponded to the cultivar RB867515. The comparative analysis of genotype dependent gene expression profile in sugarcane revealed fragments similarity with genes involved in many molecular events related to the responses of plants to different stresses, including those caused by drought. These genes work in hormonal signaling, regulation of gene transcription, senescence, DNA transposition, transport of amino acids, respiration and metabolism of carbohydrates. However, nine TDFs possibly represent still unknown genes, which may be developing important roles on the responses to drought and contributing to the trait of tolerance

Made available in DSpace on 2014-06-11T19:33:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-06-27Bitstream added on 2014-06-13T21:06:45Z : No. of bitstreams: 1 marin_a_dr_jabo.pdf: 470209 bytes, checksum: 97f3e1c5ad3ee60d8f77b0d316384609 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo do presente trabalho foi verificar o efeito de interação do estresse hídrico e da toxidez do alumínio no crescimento inicial e teores de prolina livre em duas cultivares de guandu, cv. IAPAR 43-Aratã e IAC Fava Larga, cultivadas em hidroponia. As plantas jovens foram submetidas aos estresses em solução nutritiva (pH 3,8), nos potenciais osmóticos de 0,000; -0,004; -0,006; -0,008 e -0,010 MPa com 0,00; 0,25; 0,50; 0,75 e 1,00 mmol Al3+ dm-3. O experimento foi conduzido em sala de crescimento sob luminária com irradiância média de 190 μmol m-2 s-1, fotoperíodo de 12 horas e temperatura de 25°C + 1ºC. O delineamento experimental utilizado foi inteiramente casualizado, em arranjo fatorial 2x5x5, com quatro repetições. Os dados foram submetidos às análises de regressão polinomial, agrupamento e componentes principais. Pelos resultados obtidos verifica-se que, a deficiência hídrica causa redução do crescimento da parte aérea enquanto a toxidez do alumínio provoca diminuição do crescimento radicular. Houve aumento nos teores de prolina livre nas cultivares sob deficiência hídrica e apenas na cv. IAC Fava Larga sob toxidez do alumínio. A análise multivariada mostrou alta correlação no crescimento e no acúmulo de prolina na cv. IAC Fava Larga, evidenciando provável tolerância aos estresses associados. / The objective of the present work was to study the interaction effect of water stress and aluminum toxicity on the initial growth and free proline contents in two cultivars of pigeonpea cv. IAPAR 43-Aratã and IAC Fava Larga cultivated in hydroponics. The seedlings were subjected to stresses in nutritive solution (pH 3.8), osmotic potentials 0.000; -0.004; -0.006; -0.008 and -0.010 MPa with 0.00; 0.25; 0.50; 0.75 and 1.00 mmol Al3+ dm-3. The experiment was carried out in a plant growth room under a luminary unit of average irradiance 190 μmol m-2 s-1, 12-hour photoperiod and 25ºC + 1ºC temperature. A completely randomized experimental design in factorial array 2x5x5 with four replications was used. Data were submitted to polynomial regression, cluster and main components analysis. According to the results it was verified that water stress causes growth reduction of aerial part whereas aluminum toxicity provokes radicular growth reduction. There was increase of the free proline contents in cultivars under water stress and only in cv. IAC Fava Larga under aluminum toxicity. Multivariate analysis showed high correlation in growth and accumulation of proline for the cv. IAC Fava Larga evidencing probable tolerance to associated stresses.

Submitted by MARCILENE MACHADO DOS SANTOS SARAH (marcilene.m.sarah@gmail.com) on 2018-07-20T14:51:05Z No. of bitstreams: 1 DISSERTAÇÃO - MARCILENE SARAH.pdf: 1469614 bytes, checksum: 7650422035f8634c8664c2ba24e1c108 (MD5) / Approved for entry into archive by Karina Gimenes Fernandes null (karinagi@fcav.unesp.br) on 2018-07-20T17:27:53Z (GMT) No. of bitstreams: 1 sarah_mms_me_jabo.pdf: 1469614 bytes, checksum: 7650422035f8634c8664c2ba24e1c108 (MD5) / Made available in DSpace on 2018-07-20T17:27:53Z (GMT). No. of bitstreams: 1 sarah_mms_me_jabo.pdf: 1469614 bytes, checksum: 7650422035f8634c8664c2ba24e1c108 (MD5) Previous issue date: 2018-06-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A deficiência oculta de potássio (K) é comum em feijoeiro, mas o silício (Si) quando fornecido via solução nutritiva (raiz) ou via foliar pode aliviar os estresses ocasionados pela deficiência deste nutriente, entretanto, isso ainda não é conhecido nesta espécie. A partir disso, objetivou-se verificar a melhor fonte e concentração de Si aplicado via foliar, e se essa fonte fornecida via solução nutritiva e foliar é eficiente em mitigar os estresses por deficiência de potássio em feijoeiro. Para isso, foram desenvolvidos dois experimentos em casa de vegetação com plantas de feijão cultivadas em sistema hidropônico. Um estudo preliminar visou definir a melhor fonte e concentração de Si aplicados via foliar. O segundo experimento foi em esquema fatorial 2x3, com solução nutritiva deficiente (0,2 mmol L-1 de K) e suficiente (6 mmol L-1 de K) em potássio, e o fornecimento de Si foi via solução nutritiva (2 mmol L-1 de Si), foliar (5,36 mmol L-1 de Si) e controle (0 mmol L-1 de Si), disposto em delineamento inteiramente casualizado, em 4 repetições. Foram avaliados parâmetros fisiológicos, nutricionais e crescimento das plantas. E verificou-se que a pulverização foliar com Si foi viável agronomicamente para o feijoeiro, destacando-se o silicato de sódio e potássio estabilizado na concentração de 5,36 mmol L-1. A deficiência de K causou prejuízo no desenvolvimento das plantas de feijão que não receberam Si. O Si mitigou estresses por deficiência de K no feijoeiro devido a melhoria das variáveis nutricionais, fisiológicas e de crescimento, destacando-se o fornecimento de Si via solução nutritiva em relação a via foliar, embora essa última forma de aplicação do elemento benéfico também atenuou os efeitos da deficiência do macronutriente. / Undetected potassium (K) deficiency is common in bean plants. Although silicon (Si) supplied via nutrient solution (roots) or foliar application may alleviate the resulting stress, it remains unknown in this species. This pioneering study aimed to determine the best source and concentration of leaf-applied Si, and whether providing it via nutrient solution and foliar application is efficient in alleviating K deficiency stress in bean plants. To that end, two experiments were conducted in a greenhouse with bean plants grown in a hydroponic system. Due to the lack of reliable information for the bean plant, a preliminary study aimed at determining the best leaf-applied source and concentration of Si. The second experiment used a completely randomized 2x3 factorial design, with deficient (0.2 mmol L-1 of K) and sufficient potassium solution (6 mmol L-1 of K), Si supplied via nutrient solution (2 mmol L-1 of Si), foliar application (5.36 mmol L -1 of Si) and controls (0 mmol L-1 of Si), and 4 repetitions. Physiological, nutritional and plant growth parameters were measured. Foliar spraying with Si was agronomically feasible for the bean plant, with silicate of sodium and potassium stabilized at a concentration of 5.36 mmol L -1 . K deficiency without the addition of Si compromised plant growth. Si mitigated K deficiency stress in the bean plant due to enhanced nutritional, physiological and growth variables, underscoring Si supply via nutrient solution over foliar application, although the latter also attenuated K deficiency.

Made available in DSpace on 2014-08-20T14:06:12Z (GMT). No. of bitstreams: 1 dissertacao_angela_rohr.pdf: 1097467 bytes, checksum: 6a58273c690b74d83e088521e72f61ff (MD5) Previous issue date: 2012-03-30 / The potato is the third major food crop in the world and is one of the most sensitive species to water deficit. Given the climate change scenario, the cultivation of potatoe is highly threatened, and it is urgent the need to develop varieties adapted to this demand. This work was developed aiming to characterize the genetic structure of the potato germplasm from Embrapa breeding program and to evaluate the response of potato genotypes to water deficit in two growing seasons. To evaluate the genetic structure from potato germplasm, 131 genotypes were characterized with seven SSR loci. The results showed that although the evaluated germplasm has shown a wide and unstructured genetic variability, there is a trend of narrowing the genetic base that is actually being used by the breeding program. To evaluate the response of potato genotypes to drought stress, 12 genotypes were evaluated in two seasons, spring and fall, in hydroponic culture using polyethyleneglycol to simulate a water deficit of -0.129 MPa. The genotypes were evaluated with respect to various morphological and agronomic characters, such as root and shoot dry weight as well as number of tubers produced per plant. Based on the results of this work can be seen that the potato genotypes respond differently to drought stress depending on the growing season that it is cultivated, if spring or fall. It was also found that the negative effect of drought stress in tuber development and yield is more pronounced in spring season than in autumn. / A batata é o terceiro principal alimento no mundo e é um dos cultivos mais sensíveis ao déficit hídrico. Diante do cenário de mudanças climáticas o cultivo de batata está fortemente ameaçado, sendo urgente a necessidade de desenvolver variedades adaptadas a essa demanda. Este trabalho foi desenvolvido com o objetivo de caracterizar a estrutura genética do germoplasma usado pelo programa de melhoramento da Embrapa e avaliar a resposta de genótipos de batata submetidos ao déficit hídrico em duas épocas de cultivo. O primeiro trabalho, para caracterizar a estrutura genética do germoplasma do programa de melhoramento de batata da Embrapa foi caracterizado 131 genótipos com sete loci SSR. Como resultado, embora o germoplasma avaliado tenha mostrado uma ampla variabilidade genética e não estruturada, há uma tendência de estreitamento da base genética que está efetivamente sendo utilizada pelo programa. No segundo trabalho, com o objetivo de verificar a resposta de genótipos de batata ao estresse hídrico foram avaliados doze genótipos, em duas épocas, primavera e outono, em cultivo hidropônico com o uso de polietilenoglicol simulando um déficit hídrico -0,129 Megapascal (MPa). Durante o experimento foram mensurados vários caracteres morfo-agronômicos, como a massa seca de raiz e de parte aérea e o número e massa seca de tubérculos produzidos por planta. Com base nos resultados obtidos foi constatado que os genótipos de batata respondem diferencialmente ao estresse hídrico dependendo da época de cultivo, se primavera ou outono. Também foi observado que o estresse hídrico provoca um efeito negativo no desenvolvimento e produção de tubérculos sendo que esse efeito é mais pronunciado no cultivo de primavera do que no outono.

Orientadora: Durvalina Maria Mathias dos Santos / Banca: Ricardo Andrade Reis / Banca: David Ariovaldo Banzatto / Banca: Ana Regina Pimentel de Almeida / Banca: José Antonio Proença Vieira de Moraes / Resumo: O objetivo do presente trabalho foi verificar o efeito de interação do estresse hídrico e da toxidez do alumínio no crescimento inicial e teores de prolina livre em duas cultivares de guandu, cv. IAPAR 43-Aratã e IAC Fava Larga, cultivadas em hidroponia. As plantas jovens foram submetidas aos estresses em solução nutritiva (pH 3,8), nos potenciais osmóticos de 0,000; -0,004; -0,006; -0,008 e -0,010 MPa com 0,00; 0,25; 0,50; 0,75 e 1,00 mmol Al3+ dm-3. O experimento foi conduzido em sala de crescimento sob luminária com irradiância média de 190 μmol m-2 s-1, fotoperíodo de 12 horas e temperatura de 25°C + 1ºC. O delineamento experimental utilizado foi inteiramente casualizado, em arranjo fatorial 2x5x5, com quatro repetições. Os dados foram submetidos às análises de regressão polinomial, agrupamento e componentes principais. Pelos resultados obtidos verifica-se que, a deficiência hídrica causa redução do crescimento da parte aérea enquanto a toxidez do alumínio provoca diminuição do crescimento radicular. Houve aumento nos teores de prolina livre nas cultivares sob deficiência hídrica e apenas na cv. IAC Fava Larga sob toxidez do alumínio. A análise multivariada mostrou alta correlação no crescimento e no acúmulo de prolina na cv. IAC Fava Larga, evidenciando provável tolerância aos estresses associados. / Abstract: The objective of the present work was to study the interaction effect of water stress and aluminum toxicity on the initial growth and free proline contents in two cultivars of pigeonpea cv. IAPAR 43-Aratã and IAC Fava Larga cultivated in hydroponics. The seedlings were subjected to stresses in nutritive solution (pH 3.8), osmotic potentials 0.000; -0.004; -0.006; -0.008 and -0.010 MPa with 0.00; 0.25; 0.50; 0.75 and 1.00 mmol Al3+ dm-3. The experiment was carried out in a plant growth room under a luminary unit of average irradiance 190 μmol m-2 s-1, 12-hour photoperiod and 25ºC + 1ºC temperature. A completely randomized experimental design in factorial array 2x5x5 with four replications was used. Data were submitted to polynomial regression, cluster and main components analysis. According to the results it was verified that water stress causes growth reduction of aerial part whereas aluminum toxicity provokes radicular growth reduction. There was increase of the free proline contents in cultivars under water stress and only in cv. IAC Fava Larga under aluminum toxicity. Multivariate analysis showed high correlation in growth and accumulation of proline for the cv. IAC Fava Larga evidencing probable tolerance to associated stresses. / Doutor