Potencial adaptativo de leguminosas arbóreas do Cerrado
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Data
2021-12-17
Autores
Pereira, Thalissa Cagnin
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A influência do fogo nos ecossistemas e a adaptação das plantas como resposta a esse elemento ainda é pouco compreendida. Entre os ecossistemas brasileiros que são propensos a queimadas periódicas se destaca o Cerrado, bioma complexo e heterogêneo, onde é possível encontrar uma flora bem adaptada. Afim de avaliar as estratégias envolvidas na sobrevivência de plantas após a passagem de fogo, foi realizado um estudo morfonatômico em Albizia hassleri (Chodat) Burkart e Senegalia polyphylla (DC.) Britton & Rose, antes e após o fogo, aos 6 e 18 meses. Os experimentos de queima foram conduzidos na Fazenda de Ensino Pesquisa e Extensão - UNESP - Ilha Solteira - SP, e posteriormente as plantas foram acompanhadas em casa de vegetação por 8 meses. Para os estudos anatômicos, amostras de folhas, caules e raízes foram fixadas em FAA 70, conservadas em etanol 70%, incluídas em historesina e seccionadas em micrótomo rotativo. Uma parte das lâminas foi corada com azul de toluidina, e, outra parte, foi utilizada para os testes histoquímicos. Todo o material foi fotomicrografado em microscópio óptico. Desde o primeiro mês de acompanhamento, as duas espécies apresentaram rebrota pós-fogo e baixa mortalidade, especialmente aos 18 meses. As duas espécies possuem folhas compostas, e as regiões do caule, colo da raiz e raiz já apresentam estrutura secundária, com periderme como forma de revestimento. Foi observado a presença de gemas, especialmente no colo da raiz, tanto nos indivíduos de controle quanto de pós-fogo, porém não foram verificadas diferenças anatômicas relevantes nessas duas condições. Os testes histoquímicos evidenciaram a presença de amido em ambas as espécies. De acordo com os resultados aqui apresentados, as espécies A. hassleri e S. polyphylla são resilientes ao fogo, pois possuem capacidade de regeneração, proporcionada essencialmente pelas reservas acumuladas e pela viabilidade de gemas presentes na região do colo da raiz.
The influence of fire on ecosystems and the adaptation of plants in response to this element is still poorly understood. Among the Brazilian ecosystems that are prone to periodic fires, the Cerrado stands out, a complex and heterogeneous biome, where it is possible to find a well-adapted flora. In order to evaluate the strategies involved in the survival of plants after fire, a morphonatomic study was carried out in Albizia hassleri (Chodat) Burkart and Senegalia polyphylla (DC.) Britton & Rose, before and after fire, at 6 and 18 months. The burning experiments were carried out at the Fazenda de Ensino Pesquisa e Extensão - UNESP - Ilha Solteira - SP, and then the plants were monitored in a greenhouse for 8 months. For the anatomical studies, samples of leaves, stems and roots were fixed in FAA70, preserved in 70% ethanol, included in historesin and sectioned in a rotating microtome. A part of the slides was stained with toluidine blue, and another part was used for the histochemical tests. All material was photomicrographed under an optical microscope. From the first month of follow-up, both species showed post-fire regrowth and low mortality, especially at 18 months. Both species have compound leaves, and the stem regions, the root crown and the root already present a secondary structure, with periderm as a form of covering. The presence of buds was observed, especially in the root crown, both in control and post-fire individuals, but no relevant anatomical differences were verified in these two conditions. Histochemical tests showed the presence of starch in both species. According to the results here, the species A. hassleri and S. polyphylla are resistant to fire, as they have the capacity for regeneration, essentially provided by the accumulated reserves and the viability of buds present in the root crown region.
The influence of fire on ecosystems and the adaptation of plants in response to this element is still poorly understood. Among the Brazilian ecosystems that are prone to periodic fires, the Cerrado stands out, a complex and heterogeneous biome, where it is possible to find a well-adapted flora. In order to evaluate the strategies involved in the survival of plants after fire, a morphonatomic study was carried out in Albizia hassleri (Chodat) Burkart and Senegalia polyphylla (DC.) Britton & Rose, before and after fire, at 6 and 18 months. The burning experiments were carried out at the Fazenda de Ensino Pesquisa e Extensão - UNESP - Ilha Solteira - SP, and then the plants were monitored in a greenhouse for 8 months. For the anatomical studies, samples of leaves, stems and roots were fixed in FAA70, preserved in 70% ethanol, included in historesin and sectioned in a rotating microtome. A part of the slides was stained with toluidine blue, and another part was used for the histochemical tests. All material was photomicrographed under an optical microscope. From the first month of follow-up, both species showed post-fire regrowth and low mortality, especially at 18 months. Both species have compound leaves, and the stem regions, the root crown and the root already present a secondary structure, with periderm as a form of covering. The presence of buds was observed, especially in the root crown, both in control and post-fire individuals, but no relevant anatomical differences were verified in these two conditions. Histochemical tests showed the presence of starch in both species. According to the results here, the species A. hassleri and S. polyphylla are resistant to fire, as they have the capacity for regeneration, essentially provided by the accumulated reserves and the viability of buds present in the root crown region.
Descrição
Palavras-chave
Fabaceae, Fogo, Gemas, Morfoanatomia, Rebrotamento, Fire, Buds, Morphoanatomy, Regrowth