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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Indicadores de defici?ncia h?drica em tr?s variedades de milho (Zea Marys L) / Indicators of water deficiency in three maize varieties (Zea Marys L)

Rossiello, Roberto Oscar Pereyra 10 July 1978 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-05-12T12:35:58Z No. of bitstreams: 1 1978 - Roberto Oscar Pereyra Rossielo.pdf: 1070327 bytes, checksum: 2a0b73b43c35132e3d9af4dfca0ed376 (MD5) / Made available in DSpace on 2017-05-12T12:35:58Z (GMT). No. of bitstreams: 1 1978 - Roberto Oscar Pereyra Rossielo.pdf: 1070327 bytes, checksum: 2a0b73b43c35132e3d9af4dfca0ed376 (MD5) Previous issue date: 1978-07-10 / A study was made of the effect of water stress on three corn (Zea mays L.) cultivars: Piranao, Centralmex and IPEACS III. Under the effect of a - 15 atm stress (using mannitol as osmoticum), Centralmex showed the highest percent germination while IPEACS III showed the lowest. The germination of Piran?o seeds fell in between. There also differences in root and coleoptile growths of the three varieties as compared to that of the controls (germinated in demineralized water). At a more advanced stage of grouth (6-8 leaves, plants in pots kept in a greenhouse), the soil-water stress affected the plants differently. IPEACS III continued to be severely affected but Piran?o was now the least affected, with Centralmex falling in between. The effects of water stress upon the plant metabolic patterns resulted in a increase in the leaf content of nitrate-N, free amino-N, ammonia-N, free proline and soluble sugars.181 There was on the other hand a reduction in nitrate reductase activity and protein content. Although the same general metabolic pattern was observed for the three varieties, significant differences could be detected among the varieties. These results indicated that the greenhouse environment was adequate for the study of plant responses to water stress, even enabling the distinction between varietal differences. The content of free amino-N and soluble sugars in the plant leaves showed a higher sensitivity to moderate water stress than the other indicators. A special attention was given to the study of the increase in free proline levels in the leaves. The ellucidation of the factors governing the relative accumulation of this metabolite in corn leaves requires more detailed studies. Only then could proline content be considered a safe indicator of water stress resistance for corn plants. The plants under water stress were also submitted to growth analysis. This test was very efficient for the study of dry weight and leaf expansion variation among varieties. The results of this study shows that three main factors are responsible for the plant resistance to water stress, namely: a. Tolerance to dehydration (differences in R.W.C.) b. resistance to loss in protein (differences in protein-N levels and free-N/protein-N ratios)182 c. increasc in root/shoot ratios. The present study shows the necessity of experiments with field grown plants, to check the sensitivity of the various factors studied and to compare the behavior of different corn varieties in the field with that in greenhouse. / Tr?s variedades de milho (Zea mays L.), Piran?o, Centralmex e IPEACS III, foram submetidas a stress h?drico em duas fases do crescimento vegetativo. As diferen?as na taxa e percentagem final de germina- ??o, alongamento da raiz e do cole?ptilo foram avaliadas nas tr?s variedades, quando submetidos a um stress osm?tico de -15 atmosferas, usando-se manitol como osmoticum. Centralmex mostrou a maior percentagem de germina??o final nestas candi- ??es e IPEACS III, a menor; Piran?o apresentou um comportamento intermedi?rio. Diferen?as entre as variedades nos respectivos percentuais de alongamento da raiz e cole?ptilo foram notadas ao serem comparadas com seus controles mantidos em ?gua deionizada. Quando as variedades foram comparadas em um est?gio mais avan?ado de crescimento (6-8 folhas), e o stress h?drico induzido por desseca??o progressiva do solo, em casa de vegeta??o, a variedade IPEACS III mostrou-se severamente afetada,Piran?o, relativamente, a menos afetada, apresentando Centralmex um comportamento intermedi?rio. Neste ?ltimo est?gio de crescimento, fez- se uma compara??o da sensibilidade de distintos indicadores metab?licos ? defici?ncia h?drica. Com rela??o ao metabolismo de N, foram avaliados os teores foliares de N-n?trico, N-amoniacal, N-amino livre, prolina e N-proteico. No que diz respeito ao metabolismo de carbohidratos, avaliou-se o teor foliar de carbohidratos sol?veis. Foram observados incrementos nos teores de N-amoniacal, N-n?- trico, N-amino livre, prolina e carbohidratos sol?veis. Concomitantemente, observou-se decr?scimos para o teor de N-proteico e a atividade de nitrato-reductase. Este padr?o geral de varia??o, em resposta a stress h?drico, se expressou em forma diferencial (estatisticamente significativa) entre variedades, indicando que, o ambiente proporcionado pela casa de vegeta??o foi apropriado para a separa??o dos efeitos decorrentes do stress h?drico daqueles devidos ?s caracter?sticas varietais. Os teores de N-amino livre e carbohidrato sol?vel mostraram uma maior sensibilidade a deficits h?dricos moderados. Em adi??o aos indicadores metab?licos, realizou-se a an?lise de crescimento, que mostrou ser um procedimento apropriado para descrever as varia??es em taxas de acumula??o de mat?ria seca e expans?o de ?rea foliar entre as variedades. Os dados sugeriram que, as diferen?as observadas em resist?ncia ao stress h?drico entre as variedades podem ser decorrentes de tr?s tipos de efeitos: toler?ncia ? desidrata ??o (diferen?as em C.H.R.), toler?ncia a perda de prote?nas (diferen?as nos teores de N-proteico e na rela??o N-sol?vel/ N-proteico) e incrementos na rela??o raiz/parte a?rea. A evolu??o do teor foliar de prolina foi particularmente observada nos tr?s cultivares, visando-se ligar o seu teor ? explica??o das diferen?as em sensibilidade (ou resist?ncia) ao stress h?drico. Os resultados atualmente obtidos, mostraram que, pelo menos em milho, ? necess?rio um estudo mais detido dos fatores que governam a acumula??o deste metab?lito, antes de aplicar-se indiscriminadamente este par?metro como indicador de resist?ncia ? seca. Finalmente, foi destacada a necessidade de experimenta??o direta no campo, visando a determina??o do grau de sensibilidade dos distintos indicadores e a quantifica??o das diferen?as com respeito ao comportamento das variedades em casa de vegeta??o.
2

Efeito do d?ficit h?drico sobre a express?o g?nica e morfofisiologia em Eucalyptus spp. / Effect of water stress on gene expression and morphophysiology in Eucalyptus spp.

Silva, Ina? Mari? de Ara?jo 02 August 2013 (has links)
Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-06T13:30:02Z No. of bitstreams: 2 inae_marie_araujo_silva.pdf: 2900695 bytes, checksum: b0f455759c609f430fbe59626102155a (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-06T13:30:22Z (GMT) No. of bitstreams: 2 inae_marie_araujo_silva.pdf: 2900695 bytes, checksum: b0f455759c609f430fbe59626102155a (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-06T13:30:40Z (GMT) No. of bitstreams: 2 inae_marie_araujo_silva.pdf: 2900695 bytes, checksum: b0f455759c609f430fbe59626102155a (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Made available in DSpace on 2015-01-06T13:30:40Z (GMT). No. of bitstreams: 2 inae_marie_araujo_silva.pdf: 2900695 bytes, checksum: b0f455759c609f430fbe59626102155a (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Previous issue date: 2013 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Atualmente, devido as limita??es de expans?o das tradicionais ?reas de plantio de eucalipto, v?rios grupos de pesquisa t?m buscado estrat?gias para ampliar as fronteiras florestais brasileiras. Entretanto, a baixa disponibilidade h?drica dessas regi?es fronteiri?as tem limitado o desenvolvimento de alguns gen?tipos de eucalipto. ? vista disso, objetivou-se: i) avaliar as respostas morfofisiol?gicas de dois gen?tipos de eucalipto contrastantes quanto ? suas capacidades de tolerar o d?ficit h?drico e ii) construir uma biblioteca g?nica diferencial do gen?tipo tolerante ? seca, de maneira a possibilitar ? compreens?o dos mecanismos subjacentes ? toler?ncia ao d?ficit h?drico do ponto de vista gen?tico-molecular. O experimento foi conduzido, em casa de vegeta??o na UFVJM, em Diamantina, MG. As plantas dos dois gen?tipos, clones 953 (Eucalyptus camaldulensis vs. Eucalyptus grandis) e 224 (Eucalyptus grandis vs. Eucalyptus urophylla), modelo de toler?ncia e sensibilidade ao d?ficit h?drico, respectivamente, foram aclimatadas em casa de sombra, com irriga??o, durante 30 dias. Ap?s esse per?odo, foram submetidos a dois diferentes regimes h?dricos (irrigado e n?o irrigado), quando, ent?o, foram avaliados, ao longo do per?odo experimental, o crescimento em altura e di?metro, ?rea foliar, ?ndice de clorofila total, vari?veis da fluoresc?ncia da clorofila a, vari?veis de trocas gasosas, mat?ria seca de todos os compartimentos da planta e suas rela??es derivadas (rela??o mat?ria seca raiz e parte a?rea, raz?o de massa foliar, ?rea foliar espec?fica e raz?o de ?rea foliar), al?m da sintomatologia do estresse. O experimento foi conduzido em um Delineamento Inteiramente Casualizado, em esquema fatorial 2 (gen?tipos) x 2 (regimes h?dricos), totalizando quatro tratamentos (25 repeti??es cada). As an?lises estat?sticas foram realizadas mediante an?lise de vari?ncia. Para o estudo da express?o g?nica, concomitantemente a aplica??o do estresse h?drico, folhas foram coletadas, congeladas em N2 l?quido e armazenadas a - 80 ?C. Em seguida, procedeu-se com as extra??es e purifica??es do RNA total e, posterior, constru??o da biblioteca subtrativa. A defici?ncia h?drica n?o limitou o crescimento em altura dos gen?tipos estudados, embora, tenha reduzido o di?metro e a produ??o de mat?ria seca total. As demais vari?veis morfofisiol?gicas e todas as vari?veis de trocas gasosas foram negativamente afetadas pelo d?ficit h?drico. O clone 224 mostrou-se menos eficiente em termos fotossint?ticos e mais sens?vel ? restri??o h?drica para a maioria das vari?veis analisadas. Em contrapartida, o 953 apresentou maior toler?ncia ? falta d'?gua. Possivelmente, ?rea foliar reduzida, aumentos no teor de clorofila e aparelho fotossint?tico mais eficiente podem ter sido determinantes nessa maior toler?ncia encontrada no clone 953. Essas estrat?gias, podem, portanto, serem alvos em programas de sele??o de materiais gen?ticos mais tolerantes ? seca. Nesse sentido, a efici?ncia qu?ntica do Fotossistema II mostrou-se uma caracter?stica a ser considerada num processo de sele??o para toler?ncia ? falta d'?gua. A biblioteca de cDNA constru?da permitir? identificar quais genes est?o envolvidos nesse processo de toler?ncia no gen?tipo 953. Futuramente, esses genes candidatos poder?o ser transferidos para gen?tipos de interesse econ?mico, por meio de transgenia. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Ci?ncia Florestal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2013. / ABSTRACT Currently, due to the limitations of expanding areas traditional of eucalyptus, several research groups have pursued strategies to expand the boundaries Brazilian forest. However, the low water availability of these border regions has limited the development of some genotypes of eucalyptus. Therefore, we aimed to: i) evaluate the morphological and physiological responses of two contrasting genotypes of eucalyptus as to their ability to tolerate drought and ii) build a library differential gene genotype drought tolerant, in order to enable the understanding molecular mechanisms underlying tolerance to water deficit. The experiment was conducted in a greenhouse at UFVJM in Diamantina, MG. The plants of the two genotypes, 953 clones (Eucalyptus camaldulensis vs. Eucalyptus grandis) and 224 (Eucalyptus grandis vs Eucalyptus urophylla) model of tolerance and sensitivity to water stress, respectively, were acclimated in the shade, irrigated for 30 days. After this period, underwent two different water regimes (irrigated and non-irrigated), when then were evaluated over the experimental period, the growth in height and diameter, leaf area, total chlorophyll index, chlorophyll a fluorescence variables, gas exchange variables, dry matter of all plant parts and their relations derived (shoot/root dry weight ratios, leaf weight ratio, specific leaf area and leaf area ratio) and the symptoms of stress. The experiment was conducted in a completely randomized design in a factorial 2 (genotypes) x 2 (water regimes), totaling four treatments (25 replicates each). Statistical analyzes were performed by analysis of variance. For the study of gene expression, concomitant application of water stress, leaves were collected, frozen in liquid N2 and stored at - 80 ?C. Then proceeded with the extraction and purification of total RNA and subsequent construction of the subtractive library. Water stress did not limit the growth in height of the genotypes studied, although it reduced the diameter and total dry matter production. The other morphophysiological variables and all gas exchange variables were negatively affected by drought. Clone 224 was less efficient photosynthetic and more sensitive to water restriction for most variables. In contrast, the 953 was more tolerant to lack of water. Possibly, reduced leaf area, increases in chlorophyll content and photosynthetic apparatus more efficient may have been determinant to increase tolerance found in clone 953. These strategies can be targeted in selection programs of genetic materials more drought tolerant. In this sense, the quantum efficiency of Photosystem II showed a characteristic to be considered in the selection process for tolerance to water shortage. A cDNA library constructed will allow to identify which genes are involved in the process of tolerance on the genotype 953. In the future, these candidate genes may be transferred to genotypes of economic interest through transgenesis.

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