• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 24
  • Tagged with
  • 24
  • 24
  • 15
  • 14
  • 12
  • 7
  • 7
  • 6
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 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.
21

Dispers?o de sementes de leguminosas forrageiras tropicais atrav?s das fezes de bovinos / Dispersal, germination and persistence of tropical forage legumes through bovine feces.

Silva, Tatiana Oliveira da 04 September 2008 (has links)
Submitted by Leticia Schettini (leticia@ufrrj.br) on 2016-10-10T14:09:10Z No. of bitstreams: 1 2008 - Tatiana Oliveira da Silva.pdf: 1137658 bytes, checksum: 31af0cd49ed243269ee071f1dbf32c78 (MD5) / Made available in DSpace on 2016-10-10T14:09:10Z (GMT). No. of bitstreams: 1 2008 - Tatiana Oliveira da Silva.pdf: 1137658 bytes, checksum: 31af0cd49ed243269ee071f1dbf32c78 (MD5) Previous issue date: 2008-09-04 / Legumes have some characteristics which make them able to improve pasture productivity, since they act as green manure and prevent soil erosion by weather agents. They contribute, furthermore, to maintaining or increasing soil organic matter level, since they draw carbon and fix atmospheric Nitrogen, so mobilize and recycle nutrients, increasing microbiological soil activity. Considering the useful potential of these forage plants the seed dispersal of five legume species (Pueraria phaseoloides, Neonotonia wightii, Calopogonium mucunoides, Macrotyloma axillare and Stylosanthes cv. Mineir?o) through bovine feces in an established pasture of B. decumbens was studied in two trials. In the first one seeds mixed with concentrate were offered in the late afternoon to five crossbred (Holsten-Zebu) heifers weighing 250 kg. This experiment was carried out in a crop-pasture rotation system with five paddocks occupied for 4 days. Field evaluation were made from 12 to 30 hrs after seed ingestion, consisting in marking with sticks of different colors the sites of animal droppings in order to discriminate legume species. After 73 days of pasture vacancy was made the first evaluation in order to set the number of sprouts in the research field and Pueraria phaseoloides (puero) showed the best results, followed by Macrotyloma axillare (archer) and Calopogonium mucunoides (calopo). We accessed, in addition, the drought resistance after 266 days of pasture closure counting the survival legume plants in the pasture. The best performance for plant survival after dry season was observed in archer, followed by calopo. Concerning germination after the dry season of seeding made at the beginning of the experiment, best results were found by perennial soybean, despite its low results during the dry season. A second experiment was conducted using only archer seeds as they showed the best results concerning drought persistence. Five heifers were fed with 40 g of archer seeds; the animals were kept grazing for four days at the paddock in the crop-pasture system. At the first evaluation of this experiment we observed 215 archer plants in the research field. At the second evaluation the botanical composition analysis was made revealing the presence of 6,4% of the research area covered by archer plants (global mean of 380 plants). / As leguminosas possuem algumas caracter?sticas que contribuem para a produtividade do pasto, assim como a aduba??o verde, protegendo o solo dos agentes clim?ticos. Al?m disso, as leguminosas seq?estram o carbono e fixam o nitrog?nio atmosf?rico e, assim, apresentam potencial para manter ou elevar o teor de mat?ria org?nica, mobilizar e reciclar nutrientes e favorecer a atividade biol?gica do solo. Levando em considera??o o potencial ben?fico destas planta forrageiras objetivou-se avaliar a dispers?o de sementes de cinco leguminosas forrageiras tropicais (Pueraria phaseoloides, Neonotonia wightii, Calopogonium mucunoides, Macrotyloma axillare e Stylosanthes cv. Mineir?o) atrav?s das fezes de bovinos em pastagem j? estabelecida de Brachiaria decumbens. O primeiro experimento foi realizado em sistema de lota??o rotacionada, com 5 piquetes e 2 dias de ocupa??o. As sementes das cinco leguminosas foram oferecidas a cinco novilhas mesti?as (holand?s x zebu), pesando m?dia de 250 kg, misturadas ao concentrado no fim da tarde. Entre 12 e 30 horas ap?s a ingest?o das sementes era feita uma avalia??o a campo que consistia na marca??o com bambus de diversas cores do local das deje??es dos animais, diferenciando as esp?cies. Ap?s 73 dias de descanso foi realizada a primeira avalia??o quanto ao n?mero de plantas germinadas na ?rea experimental, sendo o Pueraria phaseoloides (kudzu tropical) a esp?cie que apresentou o melhor resultado, seguido pelo Macrotiloma axillare (macrotiloma) e Calopogonium mucunoides (calopog?nio). Ainda foi avaliada a persist?ncia ? seca, ap?s 266 dias de veda??o da pastagem, contabilizando o n?mero de plantas presentes no pasto. O melhor desempenho quanto ao n?mero m?dio de plantas ap?s a seca foi alcan?ado pelo macrotiloma, sendo seguida pelo calopog?nio. Quanto ? germina??o ap?s o per?odo de seca, das sementes implantadas no in?cio do experimento, o melhor resultado foi obtido pela soja perene, apesar da sua baixa contribui??o no per?odo de seca. O segundo experimento foi realizado apenas com sementes de macrotiloma devido ao bom resultado desta esp?cie quanto ? persist?ncia ? seca. Foram oferecidos a cinco novilhas 40g de sementes de macrotiloma; os animais permaneceram no piquete por 4 dias pastejando em sistema de lota??o rotacionada. Na primeira avalia??o deste experimento obteve-se uma m?dia de 215 plantas de macrotiloma na ?rea experimental. Na segunda avalia??o foi realizado o levantamento da composi??o bot?nica da pastagem, no qual o macrotiloma teve participa??o em 6,4% da ?rea experimental, com uma m?dia total de aproximadamente 380 plantas.
22

Caracteriza??o ecofisiol?gica de sementes de esp?cies lenhosas da Caatinga

Sousa, Emerson de Medeiros 12 September 2013 (has links)
Made available in DSpace on 2014-12-17T14:33:10Z (GMT). No. of bitstreams: 1 EmersonMS_DISSERT.pdf: 1373965 bytes, checksum: d9da3378b86fd6f02be4935771c8e49a (MD5) Previous issue date: 2013-09-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Dormancy is an inherent property of the seeds that define the environmental conditions in which they are able to germinate and their presence is an adaptive trait common in species inhabiting semiarid regions. Moreover, the ability of seedling establishment in these environments has been related to the size, strength and chemical characteristics of the seeds. This study investigated patterns of dormancy and germination speed in tree species of the Caatinga, exploring how the seed size influence the processes of germination, seedling size and biomass allocation. In addition, we aim to investigate the chemical characteristics of the reserves, to verify a possible relationship between nutritional content and the process of seed germination. Therefore, seeds were collected from ten species of woody Caatinga for tests of breaking dormancy, germination and biochemical characterization. Overall, the results show that the scarification treatments mechanical and chemical, and thermal shock influenced the percentage and speed of germination in 50 % of the species, suggesting that they have some level of physical dormancy in the seeds. Biochemical characterization showed the existence of large amounts of carbohydrates in the seeds of all species, low proportion of protein and low amounts of neutral lipids. Using linear regression, we demonstrated the existence of a significant relationship between seed size and the ratio of root/shoot where the largest seeds invested a greater amount of resources for shoot growth. The relationship between germination speed and non-reducing sugar content was also significant, so these compounds is related to the maintenance of physiological seed quality. These results confirm some relationships discussed in the literature for cultivated species, but can be applied to the species native to the Caatinga / A dorm?ncia ? uma propriedade inerente ?s sementes que definem as condi??es ambientais em que estas s?o capazes de germinar e sua presen?a ? uma caracter?stica adaptativa comum em esp?cies que habitam regi?es semi?ridas. Al?m disso, a capacidade de estabelecimento das pl?ntulas nesses ambientes tem sido relacionada ao tamanho, vigor e caracter?sticas qu?micas de suas sementes. O presente estudo pretende verificar padr?es de dorm?ncia e velocidade de germina??o (IVG) em esp?cies arb?reas da Caatinga, explorando como o tamanho da semente influenciaria os processos de germina??o, tamanho das pl?ntulas e a aloca??o de biomassa. Al?m disso, almeja-se investigar caracter?sticas qu?micas das reservas, verificando uma poss?vel rela??o entre seu conte?do nutricional e o processo de germina??o das sementes. Para tanto, foram coletadas sementes de dez esp?cies arb?reas da Caatinga para a realiza??o dos testes de supera??o da dorm?ncia, germina??o e caracteriza??o bioqu?mica. No geral, os resultados mostram que os tratamentos de escarifica??o mec?nica e qu?mica, al?m do choque t?rmico influenciaram positivamente a porcentagem e velocidade de germina??o em 50% das esp?cies, sugerindo que estas apresentam algum n?vel de dorm?ncia f?sica em suas sementes. A caracteriza??o bioqu?mica mostrou a exist?ncia de grande quantidade de carboidratos nas sementes de todas as esp?cies, baixa propor??o de prote?na, e baixa quantidade de lip?dios neutros. Com o uso de regress?es lineares, foi demonstrada a exist?ncia de rela??o significativa entre o tamanho da semente e a raz?o raiz/parte a?rea, onde sementes as maiores investiram uma maior quantidade de recursos para o crescimento da parte a?rea. A rela??o entre o IVG e o teor de a??cares n?o redutores tamb?m se mostrou significativa, de forma que estes compostos tem rela??o com a manuten??o da qualidade fisiol?gica das sementes. Estes resultados corroboram algumas rela??es discutidas na literatura para esp?cies cultivadas, mas que podem ser aplicadas ?s esp?cies nativas da Caatinga
23

Conserva??o de esp?cies nativas em um assentamento rural do munic?pio de Apodi-RN: impactos socioambientais e econ?micos e o uso da biotecnologia como alternativa promissora / Conservation of native species in a rural settlement of the couty of Apodi-RN: social, environmental and economic impacts and the use of Biotechnology as a promising alternative

Bezerra, Rafaela Maria de Fran?a 01 March 2013 (has links)
Made available in DSpace on 2014-12-17T15:55:04Z (GMT). No. of bitstreams: 1 RafaelaMFB_DISSERT.pdf: 2000574 bytes, checksum: c72aa51b49be48bfd2402d6136436b13 (MD5) Previous issue date: 2013-03-01 / The Caatinga biome has a high diversity of potential and their conservation constitutes one of the greatest challenges of Brazilian science. The sustainable management of the Caatinga emerges as an alternative that through the formation of systems agrossilvipastoris, enables the use of forest resources sustainably, ensuring their conservation, regeneration and recovery. In RN this technique has been developed mainly in settlements of Agrarian Reform, such as P. A. Moaci Lucena, and their impacts go beyond the environmental aspect and reverberate socially and economically on the quality of life of family farmers. Despite the efficiency of the Sustainable Management of the Caatinga in the conservation of native species, many forests species of this biome faces serious problems of propagation and for this reason have become vulnerable to extinction, as is the case of Mimosa caesalpiniifolia Benth . Thus , it is evident the need to use sustainable alternatives to overcome the difficulties of propagation of this species and enable their replacement in areas where their existence is threatened. The Plant Biotechnology is considered as a promising alternative in this sense, considering that by micropropagation enables the large-scale production of seedlings with high health genetics status. This work has the following objectives: evaluate the perception of family farmers of P. A. Moaci Lucena in relation to social, environmental and economic impacts of the Sustainable Management of the Caatinga and check the conditions of germination and in vitro propagation of Mimosa caesalpiniifolia Benth that enabling the production of seedlings of this specie on a large scale. To achieve the first objective, semi-structured interviews showed that in the perception of farmers PA Moaci Lucena, the Sustainable Management of the Caatinga was responsible for generating many social, environmental and economic impacts that affected directly in the improvement in the quality of life of the families of the Settlement Project Moaci Lucena. Have to achieve the second objective, were investigated the influence of different substrates and concentrations of growth regulator BAP in the germination and shoot induction in vitro of Mimosa caesalpiniifolia Benth. The vermiculite was presented as the most suitable substrate for germination of this species, because it provided a more rapid germination, higher growth rates and higher dry matter accumulation. Regarding micropropagation, the concentration of 17.76 μmol/L of BAP presented a more responsive in relation to multiplication rate and the number of shoots in M. caesalpiniifolia, thus constituting the most suitable concentration for the in vitro propagation of this specie / O bioma Caatinga apresenta elevada diversidade de potenciais e a sua conserva??o constitui-se um dos maiores desafios para a ci?ncia brasileira. O Manejo Sustent?vel da Caatinga surge como uma alternativa que mediante a forma??o de sistemas agrossilvipastoris, viabiliza a utiliza??o dos recursos florestais de forma sustent?vel, assegurando a sua conserva??o, regenera??o e recupera??o. No Rio Grande do Norte essa t?cnica tem sido desenvolvida principalmente em Projetos de Assentamentos de Reforma Agr?ria, como ? o caso do P. A. Moaci Lucena, e seus impactos ultrapassam a vertente ambiental e repercutem social e economicamente na qualidade de vida de agricultores familiares. Apesar da efici?ncia do Manejo Sustent?vel da Caatinga na conserva??o de esp?cies nativas, muitas esp?cies florestais nativas deste bioma enfrentam s?rios problemas de propaga??o e por este motivo encontram-se vulner?veis ? extin??o, como ? o caso da Mimosa caesalpiniifolia Benth. Deste modo, fica evidente a necessidade de se utilizar alternativas sustent?veis que permitam contornar as dificuldades de propaga??o dessa esp?cie e viabilizem a sua reposi??o em ?reas onde a sua exist?ncia encontra-se amea?ada. A Biotecnologia Vegetal ? considerada como uma alternativa promissora nesse sentido, haja vista que mediante a micropropaga??o viabiliza a produ??o em larga escala de mudas com elevada qualidade fitossanit?ria e gen?tica. Este trabalho possui os seguintes objetivos: avaliar a percep??o dos agricultores familiares do P.A. Moaci Lucena em rela??o aos impactos socioambientais e econ?micos advindos do Manejo da Caatinga e verificar as condi??es de germina??o e propaga??o in vitro de Mimosa caesalpiniifolia Benth que viabilizem a produ??o de mudas dessa esp?cie em larga escala. Para se alcan?ar o primeiro objetivo, foram realizadas entrevistas semiestruturadas que permitiram concluir que na percep??o dos agricultores familiares do P.A. Moaci Lucena, o Manejo Sustent?vel da Caatinga foi respons?vel pela gera??o de diversos impactos socioambientais e econ?micos positivos que repercutiram diretamente na melhoria da qualidade de vida das fam?lias desse assentamento. J? para se alcan?ar o segundo objetivo, foi verificada a influ?ncia de distintos substratos e concentra??es do regulador de crescimento BAP na germina??o e indu??o de brota??es in vitro de Mimosa caesalpiniifolia Benth. A vermiculita apresentou-se como o substrato mais adequado para germina??o de sementes desta esp?cie, pois proporcionou uma germina??o mais r?pida, maiores taxas de crescimento e 9 o maior ac?mulo de mat?ria seca. Em rela??o ? micropropaga??o, a concentra??o de 17,76 μmol/L de BAP apresentou-se mais responsiva em rela??o ? taxa de multiplica??o e ao n?mero de brota??es em M. caesalpiniifolia, constituindo-se, portanto, a concentra??o mais indicada para a propaga??o in vitro dessa esp?cie
24

Testes bioqu?micos para avalia??o do vigor em sementes de Mimosa caesalpiniaefolia Benth

Avelino, Mirella Carvalho Souza 21 March 2014 (has links)
Made available in DSpace on 2014-12-17T14:17:54Z (GMT). No. of bitstreams: 1 MirellaCSA_DISSERT.pdf: 648930 bytes, checksum: 06627ea14cbf2543775d82cecd4ee6ec (MD5) Previous issue date: 2014-03-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Mimosa caesalpiniaefolia Benth. is a forest species of the Mimosaceae family, recommended for recovery of degraded areas. The evaluation of vigor by biochemical tests have been an important tool in the control of seed quality programs, and the electrical conductivity and potassium leaching the most efficient in the verifying the physiological potential. The objective, therefore, to adjust the methodology of the electrical conductivity test for seeds of M. caesalpiniaefolia, for then compare the efficiency of this test with the potassium in the evaluation of seed vigor of different lots of seeds M. caesalpiniaefolia. To test the adequacy of the electrical conductivity were used different combinations of temperatures , 25 ?C and 30 ?C, number of seeds , 25 and 50, periods of imbibition , 4 , 8 , 12 , 16 and 24 hours , and volumes deionized water, 50 mL and 75mL. For potassium leaching test, which was conducted from the results achieved by the methodology of the adequacy of the electrical conductivity test, to compare the efficiency of both tests , in the classification of seeds at different levels of vigor, and the period 4 hours also evaluated because the potassium leaching test can be more efficient in the shortest time . The best combination obtained in experiment of electrical conductivity is 25 seeds soaked in 50 mL deionized or distilled water for 8 hours at a temperature of 30 ? C. Data were subjected to analysis of variance, the means were compared with each other by F tests and Tukey at 5 % probability, and when necessary polynomial regression analysis was performed. The electrical conductivity test performed at period eight hour proved to be more efficient in the separation of seed lots M. caesalpiniaefolia at different levels of vigor compared to the potassium test / Mimosa caesalpiniaefolia Benth. ? uma esp?cie florestal pertencente ? fam?lia Mimosaceae, recomendada para recomposi??o de ?reas degradadas. A avalia??o do vigor por meio de testes bioqu?micos tem sido importante ferramenta dentro de programas de controle de qualidade de sementes, sendo os testes de condutividade el?trica e lixivia??o de pot?ssio um dos mais utilizados na verifica??o do potencial fisiol?gico. Objetivou-se, portanto, adequar a metodologia do teste de condutividade el?trica para sementes de M. caesalpiniaefolia, para ent?o comparar a efici?ncia deste teste com o de lixivia??o de pot?ssio na avalia??o de vigor das sementes dos diferentes lotes de M. caesalpiniaefolia. Para o teste de adequa??o da condutividade el?trica foram utilizadas diferentes combina??es de temperaturas, 25 e 30 ?C, de n?mero de sementes, 25 e 50, de per?odos de tempo de embebi??o, 4, 8, 12, 16 e 24 horas, e de volumes de ?gua deionizada, 50 e 75 mL. Para o teste de lixivia??o de pot?ssio, que foi realizado a partir dos resultados alcan?ados pela metodologia da adequa??o do teste de condutividade el?trica, p?de-se comparar a efici?ncia de ambos os testes, na classifica??o dos lotes das sementes em diferentes n?veis de vigor, sendo o per?odo de 4 horas tamb?m avaliado devido o teste de lixivia??o de pot?ssio poder ser mais eficiente em menor espa?o de tempo. A melhor combina??o obtida no experimento de adequa??o da condutividade el?trica ? a combina??o de 25 sementes embebidas em 50 mL de ?gua deionizada durante 8 horas a uma temperatura de 30 ?C. Os dados foram submetidos ? an?lise de vari?ncia, as m?dias comparadas entre si pelos testes F e de Tukey a 5% de probabilidade, e quando necess?rio foi realizada an?lise de regress?o polinomial. O teste de condutividade el?trica realizado no per?odo de oito horas mostra ser mais eficiente na separa??o de lotes de sementes de M. caesalpiniaefolia em diferentes n?veis de vigor comparativamente ao teste de lixivia??o de pot?ssio

Page generated in 0.0684 seconds