<p> Plants can control water loss through their stomata in response to changing environmental conditions. Some research has been done on predicting stomatal resistance from climate variables such as solar radiation intensity, temperature, and vapour pressure deficit, but the factors involved are numerous and complex. Information on evapotranspiration from non-cultivated vegetation under field conditions is relatively scarce. This study was carried out in a subarctic coastal wetland on James Bay, an area for which little data exists. Leaf resistance measurements were collected in the field with a diffusion porometer as the 1988 growing season reached its peak. Meteorological data were also recorded. The main species examined was Carex aquatilis, a common sedge with a circumpolar distribution. As has been previously found, field resistances were lower than those reported for greenhouse-grown specimens. Attempts to derive a multivariate regression model to predict leaf resistances had a maximum explained variance under 40%. However, Principal Components Analysis suggested that cool, sunny, low-VPD conditions tend to accompany low leaf resistances. An increase in leaf resistance occurs when solar radiation intensities are low, or when the air is warm and dry. In addition, Carex aquatilis from drier areas showed less growth, and generally higher leaf resistances, than plants growing in saturated soils. Since climate models predict higher temperatures and lower soil moisture for the study area, due to carbon dioxide-induced warming, higher stomatal resistances could result. If these changes are severe enough, primary production could be reduced in the subarctic wetlands. Through the food chain, this could possibly affect species important to the economy and ecology of northern areas.</p> / Thesis / Candidate in Philosophy

Extreme salinity is one of the most common environmental constraints with which legume/rhizobia symbionts must deal in arid and semi-arid regions of the world. In some areas, with good management, it has been economically possible to ameliorate the saline soil with calcium. The objective of this study, therefore, was to investigate calcium amelioration of salinity (sodicity) on nitrogen fixation, stomatal resistance, potassium/sodium ratio, and total nitrogen of Phaseolus vulgaris L. Seeds of snapbeans were grown in pots under green house conditions and were irrigated with NaCl concentrations of 0, 0.4, 0.8 or 1.2 S m-1 combined with CaS04 . 2H20 or CaCl2. 2H20 , each at concentrations of 0, 4, and 8 mM . The results show that increasing NaCl concentration decreased leaf water potential, total leaf chlorophyll, shoot and root dry weight, and nitrogen fixation but increased stomatal diffusive resistance. At the highest level of NaCl, addition of CaS04to NaCl increased leaf water potential via increasing stomatal diffusive resistance. Such effects were not observed with the addition of CaCl2 to NaCl. Addition of CaS04 to all levels of NaCl increased total leaf chlorophyll. The shoot and root dry weight and nitrogen fixation was also increased when CaS04 was added to 0.4 and 0.8 S m-1 NaCl. Again, such effects were not observed with the addition of CaCl2 to NaCl. Furthermore, analysis of leaf mineral composition showed that leaf Ca2+ , Mg2+ and K+ were increased with each increase in NaCl concentration, whereas the K+/ Na+ ratio was decreased. Also, the total leaf nitrogen increased with 0.4 and 1.2 S m-1 NaCl as well as with all levels of CaS04. Neither CaS04 nor CaCl2 had any significant effect on leaf K+, Na+, or Mg2+ of the plant when they were added to different levels of NaCl. However, leaf Ca2+ increased with an increase in concentration of CaS04 or CaCl2, but only CaS04 exhibited an interaction when combined with NaCl. Speciation modeling showed that a considerable amount of S04 was complexed as the CaS04° and NaS04- species. In spite of this, CaS04 treatment had ameliorating effect on NaCl induced salinity symptoms in snapbeans.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The increasing demand for drugs in Brazil brings us to the improvement in cultivation of medicinal plants, that amount plus the quality is recommended. This study aimed to evaluate the growth, development, essential oil production as well as gas exchange and physiological parameters in Aloysia triphylla under different water availability throughout the four seasons. The experiment was conducted in greenhouse belonging to the agroclimatology laboratory of the UFSM campus of Frederico Westphalen - RS, in a randomized complete block design with four replications. Evaluations were made on the day that marked the half of each season (summer, autumn, winter and spring), and all plant material collected 20 cm above ground. The water availability (DH) was based on the reference evapotranspiration to the external environment being applied 125, 100, 75 and 50% of ETo in an irrigation interval of two days, totaling a blade 1620.06, 1304.05; 988 , 03 and 672.02 mm. year-1, respectively. The production of biomass, height and indirect measurement of chlorophyll (SPAD) had linear and cubic responses to water availability, being negative to reduce it. The effect of seasonality reveals that the spring season has growth and biomass production stronger, surpassing all other stations, while the winter was responsible for lower growth and production. The essential oil content was positively affected by water availability, being the depth of the highest yield of 75 and 50% of ETo respectively. The seasons summer and winter detained the highest content of essential oil in the leaves. And the variables which comprise plant gas exchange with the atmosphere, perspiration was lower due to the reduction of DH, thus promoting a greater stomatal resistance and increased temperature of the sheet, and the abaxial responsible for most of the total transpiration plant. / A crescente demanda por fármacos no Brasil nos remete ao aperfeiçoamento nas práticas de cultivo de plantas medicinais, para que além de quantidade a qualidade seja preconizada. O presente trabalho teve como objetivo avaliar o crescimento, desenvolvimento, produção de óleo essencial, bem como trocas gasosas e parâmetros fisiológicos em Aloysia triphylla submetida a diferentes disponibilidades hídricas ao longo das quatro estações do ano. O experimento foi conduzido em estufa plástica pertencente ao laboratório de agroclimatologia da UFSM campus de Frederico Westphalen RS, sob um delineamento experimental de blocos completos casualizados com quatro repetições. As avaliações foram realizadas no dia que marcou a metade de cada estação do ano (verão, outono, inverno e primavera), sendo coletado todo o material vegetativo 20 cm acima do solo. A disponibilidade hídrica (DH) foi baseada na evapotranspiração de referência para o ambiente externo sendo aplicados 125, 100, 75 e 50% da ETo em um turno de rega de dois dias, totalizando uma lâmina de 1620,06; 1304,05; 988,03 e 672,02 mm. ano-1, respectivamente. A produção de biomassa, a altura e a medida indireta de clorofila (SPAD) apresentaram respostas lineares e cúbicas a disponibilidade hídrica, sendo negativo para redução da mesma. O efeito da sazonalidade nos revela que a estação primavera apresenta crescimento e produção de biomassa mais vigorosa, superando as demais estações, ao passo que o inverno foi responsável pelo menor crescimento e produção. O teor de óleo essencial foi afetado positivamente pela disponibilidade hídrica, sendo a lâmina de maior rendimento a de 75 e 50 % da ETo respectivamente. As estações do ano verão e inverno detiveram os maiores teores de óleo essencial nas folhas. Quanto as variáveis que compreendem as trocas gasosas da planta com a atmosfera, a transpiração foi menor em função da redução da DH, promovendo consequentemente uma maior resistência estomática e aumento da temperatura da folha, sendo a face abaxial responsável pela maior parte da transpiração total da planta.

Submitted by (edna.saturno@ufrpe.br) on 2016-06-16T15:38:58Z No. of bitstreams: 1 Elizamar Ciriaco da Silva.pdf: 1863733 bytes, checksum: ec224eb207a54d96ab1d9a11eceb2f54 (MD5) / Made available in DSpace on 2016-06-16T15:38:58Z (GMT). No. of bitstreams: 1 Elizamar Ciriaco da Silva.pdf: 1863733 bytes, checksum: ec224eb207a54d96ab1d9a11eceb2f54 (MD5) Previous issue date: 2008-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Among the principal native fruit trees in Northeastern Brazil, especially those found in the semi-arid areas, the umbu tree (Spondias tuberosa Arruda) represents itself as an important alternative as it well accepted by consumers and is a good produce in dry environments.Thus, the fruit trade fair or through cooperatives provides a source of supplementary income for small farmers. However, this income can be compromised by harvesting and excessive deforestation, which has intensified each year. Concern with population reduction of this species and by anthropic, Brazilian Institute for the Semi-Arid Tropic has developed studies on seedlings production, cultivation, and genetic inheritance preservation recovering genotypes with distinct morphological characteristics and deployment of a germplasm active bank provide the most promising for small producers, in addition to contributing to the reforestation of the Caatinga with a native species. Of the climatic factors limiting fruit species production in the semi-arid northeast, drought is the main factor, also allied to the growing problem of soil salinization, which has worsened each year. The mechanisms used by umbu tree to tolerate drought is not well elucidated and the physiological response before soil salinity is not yet known. Thus, the present work aimed to evaluate the physiological responses of umbu tree to drought and salt stresses. To evaluate drought responses, a project was developed in green house conditions using four grafted genotypes classified as giantumbu (BGU 44, BGU 48, BGU 50 and BGU 68) in order to evaluate the alterations on stomatal behavior, anatomical parameters, water relations and some biochemical aspects induced by intermittent drought and the possible genotypical variations. Transpiration (E) and diffusive resistance (rs) were measured daily after the beginning of the stress treatments by withholding water. When plants presented stomatal closure, the vases were re-watered and the water withhold again. This cycle was repeated for a 31 period days. The leaf water potential (Yw) was measured in four-hour intervals during a 24-hour period at the moment of the first stomatal closure and at the end of the experimental period. Total soluble carbohydrates (CHS), free amino acids (AA), protein (PROT) and proline (PRO) in leaves and roots were also measured. Certain regularity in the stomatal closure was observed among the watering period, showing differences between the species. The correlation with environmental factors suggest that, besides the water, stomatal behavior of BGU 44 and BGU 68 were influenced by Tar, RH and VPD, while the access BGU 50 were influenced by PAR and BGU 48 had no correlation with these environmental factors, suggesting that the water exerted the major influence in this genotype. Anatomical alterations in response to drought on stomatal density (DE) and reductions on stomatal index (IE) and stomatal aperture size (AO) were observed.The access BGU 48 maintained its anatomical features unaltered. There was an inversion in tissue proportion in BGU 44 under stress conditions, reducing the thickness of the spongy parenchyma and increasing palisade parenchyma. The inverse occurred with BGU 68 and theremaining genotypes continued unchanged. The lower Yw time of most of the genotypes was between 8h and 12h. The Yw of the stressed plants of BGU 44 and BGU 50 reduced significantly at 8h. The highest Yw was observed to BGU 68. The stress prolongation induced reductions in CHS content in the leaves of all genotypes. There were increases in the leaves to AA in BGUs 44 and 48, while BGUs 50 and 68 were reduced by about 40% and 43% respectively. BGU 44 and BGU 50 kept this behavior at the end of the experimental period.Significant differences in PROT content were not observed, but there were increases of 50% in PRO, except to BGU 50. Alterations on CHS, AA and PRO contents in the roots were verified and varied among the different genotypes. BGU 68 and BGU 50 were the most contrasting genotypes. In order to evaluate the salt stress responses in umbu plants a project was developed using seedlings propagated by seeds. Plants were grown in washed sand with Hoagland & Arnon nutrient solution without salt and with 25, 50, 75 and 100mM NaCl. Growth, Yw, E and rs were then evaluated. Na+, K+, Cl-, soluble carbohydrates and free amino acid contents were measured in several plant organs. Most variables were affected with salinity above 50 mM NaCl showing decreases in: number of leaves, plant height, stems diameter and dry masses and increases in root to shoot ratio. Reductions in pre-dawn leafwater potential (Ypd) were observed in plants submitted to 75 and 100 mM NaCl. Salt levels applied increased Na+ and Cl- contents in leaves. However, K+ content was not affected. A saturation to retain Na+ and Cl- in stems and roots was verified in treatments above 50 mM NaCl. These results allow us to say that there are physiological and anatomical differences among umbu tree genotypes; genotypes respond differently to intermittent drought; the turgor maintenance in umbu tree is relative to water storage in the xylopodium associated with the efficient stomatal closure mechanism and not by osmotic active solutes accumulation in either drought or salt stress conditions; due to the great variation found, the organic solutes accumulations did not demonstrate to be a good physiological trait as indicator to droughtand salt-tolerance in umbu plants. This specie tolerates salt levels until 50 mM NaCl withoutshowing significant physio-morphological alterations. / Dentre as principais fruteiras nativas do Nordeste, especialmente aquelas encontradas no semi-árido, o umbuzeiro (Spondias tuberosa Arruda) desponta com uma alternativa importante, por ser uma fruta bem aceita pelo consumidor e por ter uma boa produção em ambientes secos. Dessa forma, o comércio dos frutos em feiras livres ou através de cooperativas proporciona uma fonte de renda complementar para os pequenos agricultores. No entanto, essa renda pode ser comprometida pelo extrativismo e o desmatamento excessivos, que tem se intensificado a cada ano. Preocupada com a redução populacional desta espécie pela ação antrópica, a Embrapa Semi-Árido vem desenvolvendo estudos sobre produção de mudas, cultivo e preservação da herança genética, através da recuperação de acessos com características morfológicas distintas e a implantação de um banco ativo de germoplasma, para disponibilizar os mais promissores para os pequenos agricultores, além de contribuir com o reflorestamento da Caatinga com uma espécie nativa. Dos fatores climáticoslimitantes na produção de espécies frutíferas no semi-árido nordestino, a seca é o principal fator, aliado também ao problema crescente de salinização dos solos, que tem se agravado a cada ano. Os mecanismos utilizados pelo umbuzeiro paratolerar a seca ainda não estão completamente esclarecidos e não se conhece ainda as respostas fisiológicas frente a salinidade do solo. Desta forma, o presente trabalho objetivou avaliar as respostas fisiológicasdo umbuzeiro quando submetido às condições de seca e salinidade. Para avaliar as respostas à seca, desenvolveu-se um experimento em casa de vegetação utilizando mudas enxertadas de quatro acessos de umbuzeiro (acessos BGU 44, BGU 48, BGU 50 e BGU 68) classificados como umbu-gigante, com o objetivo de avaliar as alterações no comportamento estomático, parâmetros anatômicos, relações hídricas e alguns parâmetros bioquímicos induzidos pela seca intermitente, além das possíveis variações genotípicas. Foram efetuadas mensurações da transpiração (E) e da resistência difusiva (rs) diariamente após a suspensão da rega até ocorrer o fechamento estomático, momento em que as plantas foram re-irrigadas. A rega foi suspensa novamente até ocorrer novo fechamento estomático e este ciclo foi repetido por um período de 31 dias. O potencial hídrico foliar (Yw) foi determinado em dois cursos nictimerais (no momento do primeiro fechamento estomático e ao final do período experimental). Também foram avaliados os teores de carboidratos solúveis totais (CHS), aminoácidos livres (AA), proteína (PROT) e prolina (PRO) nas folhas e nas raízes, assim como alterações anatômicas. Os acessos apresentaram regularidade no período de fechamento estomático entre as regas, demonstrando diferenças intra-específicas. Houve correlação com as variáveis ambientais sugerindo que, além da água, o comportamento estomático dos acessos BGU 44 e BGU 68sofreram influência da Tar, UR e DPV, enquanto que o acesso BGU 50 sofreu influência do PAR e o BGU 48 não se correlacionou com os outros fatores, indicando que a água foi o fator que exerceu maior influência neste acesso. Alterações anatômicas em resposta à seca foramobservadas na densidade de estômatos (DE), reduções no índice estomático (IE) e na abertura do ostíolo (AO). O acesso BGU 48 manteve as características anatômicas inalteradas. Houve uma inversão na proporção dos tecidos do acesso BGU 44 quando sob estresse, diminuindo a espessura do parênquima lacunoso e aumentando o parênquima paliçádico. O inverso ocorreu com o BGU 68 e os demais acessos permaneceram inalterados. O horário de menor Yw para a maioria dos acessos foi entre 8h e 12h. O Yw das plantas estressadas do BGU 44 e BGU 50 foi reduzido significativamente às 8h. O BGU 68 apresentou os valores mais elevados de Yw. O prolongamento do estresse provocou reduções nos teores de CHS nas folhas de todos os acessos. Houve aumento no teor de AA nas folhas dos BGU’s 44 e 48, enquanto que os BGU’s 50 e 68 reduziram 40% e 43%, respectivamente. Ao final do período experimental esse comportamento se manteve para o BGU 44 e o BGU 50. Não houve diferença significativa para os teores de PROT nas folhas, mas houve aumento de 50% nos teores de PRO, exceto para o BGU 50. Foram verificadas alterações na concentração de CHS, AA e PRO nas raízes, com diferença entre os acessos. Os acessos BGU 68 e BGU 50 foram os mais contrastantes em condições de seca. Para avaliar as respostas do umbuzeiro ao estresse salino, foi desenvolvido um experimento utilizando-se plantas propagadas por sementes. As plantas foram cultivadas em areia lavada, regadas com solução nutritiva de Hoagland & Arnon, sem ecom adição de NaCl (25, 50, 75 e 100 mM). Avaliou-se o crescimento, o Yw, E e rs. O teor de Na+, K+, Cl-, carboidratos solúveis e aminoácidos livres foram dosados nos diversos órgãos da planta. A maioria das variáveis estudadas foi afetada em níveis de NaCl de 50 mM, reduzindo o número de folhas, a altura das plantas, o diâmetro do caule e a massa seca e aumentando a relação raiz/parte aérea (R/Pa). O potencial hídrico foliar antes do amanhecer (Ypd) foi reduzido nas plantas dos tratamentos 75 e 100 mM de NaCl. A concentração de Na+ e Cl- nas folhas aumentou em função dos níveis de NaCl aplicados, mas, o teor de K+ não foi afetado. Nos caules e raízes, houve uma saturação na retenção de Na+ e Cl- nos tratamentos acima de 50 mM. Os resultados desta pesquisa permite inferir que existem diferenças fisiológicas e anatômicas entre os acessos de umbuzeiro estudados; que eles respondem de forma diferente à seca intermitente; que a manutenção da turgescência foliar está relacionada à reserva de água nos xilopódios associado ao mecanismo de fechamento estomático eficiente e não ao acúmulo de solutos osmoticamente ativos, tanto em situação de seca como de salinidade no meio; devido à grande variação encontrada, o acúmulo de solutos orgânicos não demonstrou ser um mecanismo fisiológico indicador de tolerância à seca e a salinidade nesta espécie; o umbuzeiro tolera níveis de salinidade de até 50 mM de NaCl sem apresentar alteraçõesfisiomorfológicas significativas na fase inicial do desenvolvimento.

La réduction de la consommation de l’eau dans les serres agricoles représente un grand intérêt ne serait-ce que pour accroitre l’efficience d’utilisation de l’eau par les cultures et rendre les professionnelsdu secteur horticole plus compétitifs. La thèse vise à apporter des réponses concernant la gestion optimale de l’eau. Ceci passe par la mise en place d’un modèle capable de prédire les bilans demasse et d’énergie sur l’ensemble du continuum substrat-planteatmosphère en régimes de confort et de restriction hydrique. La plupart des modèles de transfert existants se focalisent soit surle système sol-plante, soit sur le système plante-atmosphère. Ils ont de plus été établis principalement pour les systèmes de grandes cultures, alors que les cultures en pot sous serre possèdent desspécifi cités liées au confi nement tant aérien que racinaire. L’enjeu est de bâtir une approche intégrée du continuum substrat-planteatmosphère pour modéliser le fonctionnement de plantes en pots sousserre. La thèse s’appuie sur une double approche expérimentale et numérique. Une campagne expérimentale a été lancée en 2014 puis en 2015 sous serre et une autre en chambre climatique en 2014,en utilisant l’Impatiens de Nouvelle Guinée comme plante modèle. Il s’agissait d’abord d’élaborer un modèle de la résistance stomatique, élément clef de la transpiration en s’appuyant sur le modèleméthode multiplicatif de Jarvis puis sur la méthode des plans d’expérience en confort et en restriction hydrique. Les données acquises ont permis de caler/valider ces modèles de résistance,qui ont pu êtr / In greenhouses, reducing water consumption is of high interest, not only to increase water effi ciency, but also to maintain competitiveness of the growers. The aim of this thesis is to provideanswers regarding the optimal water management. To reach this goal, predictive models water and energy transfers through the substrate-plant-atmosphere are implemented, considering wellwatered plants and plants under water restriction. Most existing models of water and energy transfers have benne established either on the soil-plants system, or on theplant-atmosphere system. Moreover, such models were mainly developed for open fi eld conditions, although plants grown in pots have specifi cities linked to the aerial and root confi nement.The challenge is therefore to develop an integrated soil-plantatmosphere model for greenhouse plants grown in pot. The thesis was based on a combined experimental and numerical approach.A field survey was conducted in 2014 and then in 2015 inside a greenhouse, and another one in a growth chamber in 2014. The New Guinea Impatiens was used as a plant model. The stomatal resistance was fi rst modeled, as a key factor impacting the transpiration, by using the multiplicative Jarvis model, andthen the design of experiments method for plants under wellwatered and water restriction conditions. The collected data was used to calibrate/validate the aforementioned stomatalresistance models; the obtained models could then be tested to evaluate transpiration with the Penman Monteith model and the direct method. Finally, these models were integrated in