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

Os poliésteres alifáticos, como poli(caprolactona) (PCL) e poli(ácido lático) (PLA), são comumente usados em produtos biodegradáveis. Esses materiais são ecológicos e o uso de fibras vegetais com estes polímeros corrobora em uma alternativa de lidar com os resíduos da agroindústria e da indústria madeireira. O objetivo deste estudo foi de investigar as propriedades resultantes da degradação abiótica e biótica das bioblendas de PCL/PLA e seus biocompósitos com fibras vegetais. As fibras vegetais avaliadas foram a de babassu (Orbignya phalerata), de cana-de-açúcar (Saccharum spp) e farinha de madeira (Pinus Ellioti). A bioblenda de PCL/PLA foi utilizada como referência na proporção de 70/30, 50/50 e 30/70 (m/m) e para cada biocompósito foi utilizado 20% de fibra vegetal com duas granulometrias, de 35 e 45 mesh. As misturas foram processadas via extrusão e moldados por compressão térmica em formato de fitas. As amostras foram expostas a intemperismo natural por um período total de 120 dias e avaliadas as mudanças de suas propriedades mecânicas, físicas, químicas, morfológicas e térmicas a cada 30 dias. Evoluções das superfícies deterioradas das amostras foram observadas por MEV e demonstraram que foram ocasionadas pelas condições climáticas severas e confirmadas por FTIR através de uma diminuição considerável dos grupos ésteres. A incorporação de maior quantidade PLA ao PCL nas bioblendas aumentou o módulo de elasticidade e resistência à tração. Os biocompósitos reforçados com fibras vegetais com granulometria de 45 mesh destacaram-se em maior resistência à tração, e, após envelhecimento natural de 30 dias apresentaram menor decaimento assim como o módulo elástico. A estabilidade térmica dos biocompósitos com farinha de madeira de Pinus e fibras de cana-de-açúcar foi maior do que as de babaçu. O biocompósito reforçado com fibras de cana-de-açúcar destacou-se com maior desempenho mecânico indicando que houve uma melhor interação entre fibra e matriz polimérica. Resultados do monitoramento da degradação biótica avaliados em câmara respirométrica indicaram que o PCL apresentou menor velocidade de biodegradação em relação ao PLA. As bioblendas e biocompósitos com maior teor de PCL mostraram menor produção de CO2 ao longo do período avaliado. O biocompósito com menor teor de PCL e reforçado com fibra de cana-de-açúcar destacou-se com uma maior velocidade de biodegradação e pela maior produção de CO2. As propriedades resultantes da degradação abiótica e biótica destes materiais auxiliam no desenvolvimento de produtos de vida útil curta, bem como, na preservação do meio ambiente. / Aliphatic polyesters, such as poly(caprolactone) (PCL) and poly(lactic acid) (PLA) have been commonly used in biodegradable products. These materials are ecological and use of vegetal fibers in these composites also provides an alternative way to deal with agricultural residues. This study aims to evaluate the properties resulting from the abiotic and biotic degradation of PCL/PLA bioblends and their biocomposites. The vegetal fibers evaluated were babassu (Orbignya phalerata), sugarcane (Saccharum spp) and wood flour (Pinus Ellioti). PCL/PLA bioblends were used as reference with 70/30, 50/50 and 30/70 (w/w) ratio and each biocomposite had 20% of vegetal fiber content with 35 and 45 mesh granulometry was used. The bioblends were processed by extrusion and molded in tape format. The samples were exposed to natural weathering for 120 days and the changes in their mechanical, physical, chemical, morphological and thermal properties were evaluated every 30 days. Damaged surface evolution was performed by SEM and showed that they were caused by the severe climatic conditions and confirmed by FTIR through a considerable decrease of the ester groups. Addition of PLA to the PCL in the bioblends increased the modulus of elasticity and tensile strength. Reinforcements with vegetable fibers with 45 mesh granulometry increased tensile strength, and, after natural aging of 30 days, showed lower decrease as well as the modulus. Thermal stability of the biocomposites with wood flour and sugarcane fibers was higher than babassu. Biocomposites reinforced with sugarcane fibers highlighted in the higher mechanical performance indicating that there was a better interaction between fiber and polymer matrix. Results of the monitoring of biotic degradation indicated that PCL presented a lower rate of biodegradation in relation to PLA. Bioblends and biocomposites with higher PCL content showed lower CO2 generation over the period evaluated. Biocomposites with lower content of PCL and reinforced with sugarcane fiber stood out in the greater speed of biodegradation and the greater production of CO2. Properties resulting from the abiotic and biotic degradation prompted changes in its structures and to facilitate its degradation in times lower than conventional and aid in the development of short-lived products as well as in the preservation of the environment.

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.

Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmacognosy Candidate: Tereza Ošťádalová Supervisor: Doc. PharmDr. Lenka Tůmová, CSc. Title of diploma thesis: The selenium effect on secondary metabolites production in in vitro cultures of medicinal plants - II. Key words: callus, suspension culture, abiotic elicitor, selenium, Fagopyrum In vitro plant cultures usually produce only a small amount of secondary metabolites. The method of elicitation is one of the options how to increase the production of these substances. The effect of selenium as abiotic elicitor on rutin production in callus and suspension culture of Fagopyrum esculentum Moench., variety Pyra was observed in this study. The release of rutin into the nutrient medium was studied as well. The cultivation was performed in Murashige and Skoog (MS) nutrient medium which was enriched with 1 mg/l of 2,4-dichlorophenoxyacetic acid. The solution of selenium in three different concentrations (c1 = 9.012.10-3 mol/l, c2 = 9.012.10-4 mol/l, c3 = 9.012.10-5 mol/l) was used. The samples were taken after 6, 12, 24, 48, 72 and 168 hours of elicitor treatment. The rutin content was determined by high-performance liquid chromatography (HPLC). The elicitation led to increasing of rutin amount in callus and also in suspension...

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.

In the present M. Sc. thesis the effect of water temperature (thermal range: 17.4 - 38.6 °C) on early life history (during interval from egg fertilization to full yolk sac depletion by 50 % of larvae; Fe - Re50) in African catfish (Clarias gariepinus) was examined. Length of the incubation period (i. e. interval from egg fertilization to the moment of hatching of 50 % of individuals; Fe - H50), length of the hatching period (i. e. interval from hatching of 5 % of individuals to hatching of 95 % of individuals; H5 - H95), length of the period up to the first intake of exogenous food (i. e. interval from H50 to the first intake of exogenous food by 50 % of individuals; H50 - S50) and length of the period up to the full yolk sac resorption (H50 - Re50) were inversely proportional to the incubation temperature. Period of the yolk sac resorption was significantly prolonged (approximately six times) because of using of exogenous food (compared to treatments without added external food supplies). Embryonic development was theoretically stopped at temperature 15.4 °C and hatching occured after c. 12 effective day-degrees. Size of larvae increased during embryonic and larval period. Size of larvae at H50, S50 and Re50, was inversely proportional dependent on the incubation temperature. Size of individuals at Re50 was increased (approximately twice) because of using of exogenous food (compared to treatments without added external food supplies). Yolk sac volume (YsV) decreased during embryonic and larval period. YsV at H50 was correlated with size of egg and YsV was S50 was inversely proportional to the incubation temperature. A dry weight of yolk sac at H50 represented c. 89 % of total dry weight of hatched larvae. During the period of endogenous feeding c. 75 % of dry weight of egg was converted into the larval somatic tissues. Efficiency of energy conversion during the period of endogenous feeding is lower (60 %). The energetical value of total dry matter and content of sulfur in dry matter was decreasing during the period of endogenous feeding (in order: egg, hatched larvae, larvae at Re50). Content of nitrogen and carbon in dry matter was increasing during the embryonic period and afterwards was decreasing during the larval period. In term of survival, the zone of thermal tolerance for early life history in African catfish ranges from 19 to 33 °C (with thermal optimum between 23 and 30 °C), i. e. this fish belongs to the typical thermophilous species. The suboptimal temperatures lies within intervals 21 - 23 °C and 30 - 33 °C, respectively. Temperatures below 17.5 °C as well above 35.5 °C can be considered as the lethal temperatures already during embryonic period and those below 19 °C and above 33 °C as the lethal ones during larval period, respectively. In term of bioenergy, the thermal optimum for early life history in African catfish lies between 23 - 28 °C.

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.