Efeito da predação por Acanthoscelides schrankiae(Coleoptera: Bruchidae) e de altas temperaturas na germinação de sementes de Mimosa bimucronata (DC.) Kuntze (Fabaceae: Mimosoideae)
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Data
2008-04-25
Autores
Menezes, Luciana Cristina Candido Ribeiro de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Mimosa bimucronata (DC.) Kuntze (Fabaceae: Mimosoideae) é uma planta perene, arbórea, altamente ramificada e espinhosa, podendo atingir 8 metros de altura, nativa do Brasil e com reprodução por sementes, e suas sementes, durante a fenofase de frutificação, são intensamente predadas por bruquídeos da espécie Acanthoscelides schrankiae. Porém, há poucos estudos sobre a predação de sementes em M. bimucronata. Apesar de estar localizada em regiões próximas a cursos d’água, M. bimucronata geralmente está envolta por vegetação composta de plantas invasoras herbáceas, na maioria gramíneas, e durante a estação seca é comum a ocorrência de queimadas naturais. No presente estudo investigou-se a hipótese de que o processo germinativo das sementes de M. bimucronata pode ser acelerado após exposição moderada ao fogo. Além disso, estudou-se a relação entre a qualidade das sementes de M. bimucronata e as seguintes variáveis: (1) porcentagem de germinação de sementes sadias provenientes de frutos infestados e não infestados; (2) peso seco de plântulas provenientes de frutos infestados e não infestados; e (3) peso corporal de A. schrankiae. Também foi estudado o efeito da predação de frutos na alocação de recursos e compostos secundários (taninos) nas sementes sadias. Os experimentos relacionados a predação de sementes foram realizados comparando-se duas populações de plantas (Lageado e Rubião), em que 25 plantas foram marcadas ao acaso, sendo 15 pertencentes ao Lageado e 10 a Rubião, e 4 ramos por planta foram ensacados. Os demais ramos ficaram expostos a infestação por bruquídeos. As sementes viáveis dos frutos maduros, coletados dos ramos ensacados e também dos ramos livres, foram utilizadas para as análises dos conteúdos de nitrogênio e taninos, e também para os testes...
Mimosa bimucronata (DC.) Kuntze (Fabaceae: Mimosoideae) is a perennial, arborous, highly branched and spiny plant, reaching a height of 8 m meters high, endemic to Brazil, with seed reproduction. During fructification, M. bimucronata seeds are highly attacked by the bruchid Acanthoscelides schrankiae, although few studies about seeds predation on M. bimucronata are found. Despite being localized on margins of water courses, M. bimucronata is usually surrounded by herbaceous vegetation, mostly grasses, and during the dry season natural burnings are common. This study investigated the hypothesis that the germination process of M. bimucronatai seeds is accelerated after fire treatments. It was also investigated the relationship among the quality of M. bimucronata seeds and the following variables: (1) percentage of germination of viable seeds from infested and non-infested fruits; (2) dry weights of seedlings from infested and non-infested fruits; and (3) body dry weights of A. schrankiae. It was also investigated whether fruit predation affect allocation of resources and secondary compounds (tannins) in viable seeds. Experiments related to seed predation were carried out comparing seeds from two plant populations (Lageado and Rubião). Twenty-five plants were selected at random with 15 from Lageado and 10 from Rubião, and four branches per plant were bagged. The other branches were exposed to predation by bruchids. Viable seeds from mature fruits were collected from bagged and non-bagged branches in order to perform nitrogen and tannins analysis and germination tests. Dry weights of seedlings and adult bruchids were recorded. The results showed that M. bimucronata seeds from non-infested fruits presented better germination than seeds from infested fruits, showing that seed ...(Complete abstract click electronic access below)
Mimosa bimucronata (DC.) Kuntze (Fabaceae: Mimosoideae) is a perennial, arborous, highly branched and spiny plant, reaching a height of 8 m meters high, endemic to Brazil, with seed reproduction. During fructification, M. bimucronata seeds are highly attacked by the bruchid Acanthoscelides schrankiae, although few studies about seeds predation on M. bimucronata are found. Despite being localized on margins of water courses, M. bimucronata is usually surrounded by herbaceous vegetation, mostly grasses, and during the dry season natural burnings are common. This study investigated the hypothesis that the germination process of M. bimucronatai seeds is accelerated after fire treatments. It was also investigated the relationship among the quality of M. bimucronata seeds and the following variables: (1) percentage of germination of viable seeds from infested and non-infested fruits; (2) dry weights of seedlings from infested and non-infested fruits; and (3) body dry weights of A. schrankiae. It was also investigated whether fruit predation affect allocation of resources and secondary compounds (tannins) in viable seeds. Experiments related to seed predation were carried out comparing seeds from two plant populations (Lageado and Rubião). Twenty-five plants were selected at random with 15 from Lageado and 10 from Rubião, and four branches per plant were bagged. The other branches were exposed to predation by bruchids. Viable seeds from mature fruits were collected from bagged and non-bagged branches in order to perform nitrogen and tannins analysis and germination tests. Dry weights of seedlings and adult bruchids were recorded. The results showed that M. bimucronata seeds from non-infested fruits presented better germination than seeds from infested fruits, showing that seed ...(Complete abstract click electronic access below)
Descrição
Palavras-chave
Botânica, Ecologia vegetal, Relação inseto-planta, Predação de sementes, Germinação, Seed predation, Germination
Como citar
MENEZES, Luciana Cristina Candido Ribeiro de. Efeito da predação por Acanthoscelides schrankiae(Coleoptera: Bruchidae) e de altas temperaturas na germinação de sementes de Mimosa bimucronata (DC.) Kuntze (Fabaceae: Mimosoideae). 2008. 80 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências de Botucatu, 2008.