Respostas fisiológicas e morfológicas de sementes de palmito juçara (Euterpe edulis Mart.) à luz, temperatura, desidratação e aplicação de giberelinas
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Data
2011-03-25
Autores
Roberto, Guilherme Garcia [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Euterpe edulis (Mart.), ou palmiteiro juçara, é uma espécie-chave da mata Atlântica ameaçada de extinção devido à alta taxa de corte não seletivo. Seu desenvolvimento a partir da germinação é muito lento, resposta típica das espécies da família Arecaceae. Visando melhorar sua reposição no meio natural, objetivou-se entender e otimizar a germinação de sementes de E. edulis. No primeiro estudo objetivou-se determinar: condições ótimas de temperatura e luz (claro X escuro); o início da fase de retomada do metabolismo da curva de embebição, para a aplicação de tratamentos promotores de germinação; e a resposta à aplicação de hormônios durante a germinação. Foi observado que a aplicação de 50 mg L-1 de ácido giberélico (GA3), aos 12 dias após a semeadura (DAS), a 25ºC no escuro, aumentou o desempenho germinativo (porcentagem, velocidade e sincronização da germinação) de sementes de E. edulis. Não foram observados indícios anatômicos de divisão e/ou alongamento celular em sementes 15 dias após o tratamento com GA3. De posse dessas informações, no segundo estudo foram testadas as hipóteses: (i) sementes de E. edulis apresentam maior desempenho germinativo quanto mais bem hidratado for o tecido; (ii) por serem recalcitrantes, sementes de E. edulis têm desenvolvimento contínuo; logo, é indiferente o momento (0 ou 12 DAS) da germinação em que é aplicado GA3; (iii) alterações anatômicas indicativas de crescimento embrionário só podem ser observadas após 15 dias da aplicação de GA3; (iv) de que o maior desempenho germinativo de sementes de E. edulis tratadas com GA3 é resultado da ação hormonal indutiva da mobilização de reservas. Através de testes de germinação, de quantificação de reservas e anatomia das sementes respostas fisiológicas a perda de água e a aplicação de GA3, foram confirmadas as hipóteses (i), (ii) e (iii)...
Euterpe edulis (Mart.), or jussara palm, is a key species from the Atlantic forest threatened to extinction due to the high rate of non-selective cutting. His development from germination is very slow, a typical response of species from the Arecaceae family. In order to improve its natural replacement on the environment, this study aimed to understand and optimize the germination of E. edulis seeds. In the first study was determined: the optimal conditions of temperature and light (light X shade), the start of metabolism resumption of imbibition curve, when seeds could be treated for germination enhancement and the germination response to hormone application during germination. It was observed that the application of gibberellic acid (GA3) 50 mg L-1, 12 days after sowing (DAS), 25°C in the dark, increased germination performance (percentage, speed and synchronization of germination) of E. edulis seeds. There was no anatomical evidence of division and / or cell elongation in seeds 15 days after treatment with GA3. With this observations, the second study tested the hypotheses: (i) seeds of E. edulis have higher germination performance as much better hydrated is the tissue, (ii) being recalcitrant, seeds of E. edulis have continuous development, therefore it is irrelevant the moment (0 or 12 DAS) of germination in with GA3 is applied, (iii) anatomical abnormalities indicative of embryonic growth can only be observed after 15 days from the application of GA3, (iv) that the greatest performance of germination of E. edulis with GA3 is the result of inductive hormonal mobilization of reserves. Physiological responses to water loss and application of GA3 were obtained through germination tests, quantification of reserves and seed anatomy. The hypotheses (i), (ii) and (iii) were confirmed. The hypothesis (iv) could not be confirmed. We conclude that although the maintenance of the characteristic... (Complete abstract click electronic access below)
Euterpe edulis (Mart.), or jussara palm, is a key species from the Atlantic forest threatened to extinction due to the high rate of non-selective cutting. His development from germination is very slow, a typical response of species from the Arecaceae family. In order to improve its natural replacement on the environment, this study aimed to understand and optimize the germination of E. edulis seeds. In the first study was determined: the optimal conditions of temperature and light (light X shade), the start of metabolism resumption of imbibition curve, when seeds could be treated for germination enhancement and the germination response to hormone application during germination. It was observed that the application of gibberellic acid (GA3) 50 mg L-1, 12 days after sowing (DAS), 25°C in the dark, increased germination performance (percentage, speed and synchronization of germination) of E. edulis seeds. There was no anatomical evidence of division and / or cell elongation in seeds 15 days after treatment with GA3. With this observations, the second study tested the hypotheses: (i) seeds of E. edulis have higher germination performance as much better hydrated is the tissue, (ii) being recalcitrant, seeds of E. edulis have continuous development, therefore it is irrelevant the moment (0 or 12 DAS) of germination in with GA3 is applied, (iii) anatomical abnormalities indicative of embryonic growth can only be observed after 15 days from the application of GA3, (iv) that the greatest performance of germination of E. edulis with GA3 is the result of inductive hormonal mobilization of reserves. Physiological responses to water loss and application of GA3 were obtained through germination tests, quantification of reserves and seed anatomy. The hypotheses (i), (ii) and (iii) were confirmed. The hypothesis (iv) could not be confirmed. We conclude that although the maintenance of the characteristic... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Fisiologia vegetal, Palmeira - Sementes, Germinação, Mata Atlântica, Curva de embebição, Fitohormôniod, Physiology of plants
Como citar
ROBERTO, Guilherme Garcia. Respostas fisiológicas e morfológicas de sementes de palmito juçara (Euterpe edulis Mart.) à luz, temperatura, desidratação e aplicação de giberelinas. 2011. 46 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências de Rio Claro, 2011.