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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
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/14047 |
| Date | 12 September 2013 |
| Creators | Sousa, Emerson de Medeiros |
| Contributors | CPF:10250312883, http://lattes.cnpq.br/3024078007563102, Souza, Alexandre Fadigas de, CPF:02845395701, http://lattes.cnpq.br/7844758818522706, Voigt, Eduardo Luiz, CPF:93216717991, http://lattes.cnpq.br/2455621187263790, Pacheco, Mauro Vasconcelos, CPF:04606379677, http://lattes.cnpq.br/1488351961014416, Ganade, Gislene Maria da Silva |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Ecologia, UFRN, BR, Bioecologia Aqu?tica |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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