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Estudo fenológico e bioquímico da germinação de 4 espécies nativas da Madeira
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Abstract(s)
O presente trabalho teve como objetivo aprofundar o conhecimento do processo de
germinação de quatro espécies nativas lenhosas da Madeira (Teline maderensis Webb &
Berthel., Laurus novocanariensis Rivas Mart., Lousa, Fern. Prieto, E. Dias, J.C. Costa & C.
Aguiar, Vaccinium padifolium Sm. e Myrica faya Aiton). O estado do conhecimento sobre a
germinação destas espécies é limitado, condicionando a obtenção de sementes com qualidade
que permitam assegurar a viabilidade e elevados padrões de germinação. Assim, foram
realizados ensaios com sementes em diferentes estados de maturação. Lotes de sementes
foram colocados a germinar em locais distintos da ilha da Madeira, de forma a testar a
influência das condições edafoclimáticas. Foi igualmente testada a germinação das sementes
em estufa e em diferentes tipos de substratos. Posteriormente, sementes foram submetidas a
distintos tratamentos pré-germinativos e colocadas em câmaras fitoclimáticas para estudar a
presença de dormências associadas. Por fim, avaliou-se a alteração da composição
bioquímica das sementes durante a germinação e o papel de dois marcadores do metabolismo.
O sucesso germinativo variou conforme as espécies. O Vaccinium padifolium
apresentou a melhor taxa de germinação nas sementes com estado de maturação mais
avançado. A espécie exibiu um sucesso superior a 75% nos ensaios realizados em câmara
fitoclimática. O Laurus novocanariensis obteve a melhor percentagem de germinação em
campo e em estufa, variando entre os 76,67% e os 90%. A Myrica faya e a Teline maderensis
obtiveram taxas mais elevadas em laboratório, superiores a 66% e 71%, respetivamente.
Em termos de composição bioquímica, as quatro espécies apresentaram maior
concentração de amido no estado de maturação mais avançado. Nos açucares, as concentrações
são marcadamente reduzidas para a maioria das amostras. Os lípidos e a proteína bruta
exibiram baixa taxa de mobilização durante a germinação. O Laurus novocanariensis
apresentou a redução mais acentuada em açucares solúveis, lípidos e proteína durante o
processo germinativo (84,43%, 28,41% e 17,63%, respetivamente), e a Myrica faya a espécie
que obteve maior mobilização em amido (81,65%). Quanto aos marcadores do metabolismo,
a malato-desidrogenase apresenta um aumento da atividade enzimática durante a germinação
e na peroxidase observou-se uma baixa atividade em todas as amostras.
The aim of this study was to deepen the understanding of the germination process of four native woody species from Madeira (Teline maderensis Webb & Berthel., Laurus novocanariensis Rivas Mart., Lousa, Fern. Prieto, E. Dias, J.C. Costa & C. Aguiar, Vaccinium padifolium Sm. and Myrica faya Aiton). Current knowledge on the germination of these species is limited, making it difficult to obtain quality seeds that ensure viability and high germination standards. Trials were conducted with seeds at different stages of ripeness. Seed batches were germinated in various locations on Madeira to test the influence of soil and climatic conditions. Seed germination was also tested in greenhouses and on different substrates. Subsequently, seeds underwent different pre-germination treatments and were placed in phytoclimatic chambers to study associated dormancy. Finally, changes in the biochemical composition of the seeds during germination and the role of two metabolic markers were assessed. Germination success varied by species. Vaccinium padifolium showed the best germination rate in seeds at a more advanced stage of ripeness, with a success rate exceeding 75% in phytoclimatic chamber. Laurus novocanariensis had the highest germination percentage in the field and greenhouse, ranging from 76.67% to 90%. Myrica faya and Teline maderensis achieved higher rates in the laboratory, over 66% and 71%, respectively. In terms of biochemical composition, the four species showed the highest starch concentration at the most advanced stage of ripeness. Sugar concentrations were markedly low in most samples. Lipids and crude protein exhibited a low rate of mobilization during germination. Laurus novocanariensis showed the sharpest reduction in soluble sugars, lipids, and protein during germination (84.43%, 28.41%, and 17.63%, respectively), while Myrica faya exhibited the highest starch mobilization (81.65%). Regarding metabolic markers, malate dehydrogenase showed increased enzymatic activity during germination and peroxidase activity was low in all samples.
The aim of this study was to deepen the understanding of the germination process of four native woody species from Madeira (Teline maderensis Webb & Berthel., Laurus novocanariensis Rivas Mart., Lousa, Fern. Prieto, E. Dias, J.C. Costa & C. Aguiar, Vaccinium padifolium Sm. and Myrica faya Aiton). Current knowledge on the germination of these species is limited, making it difficult to obtain quality seeds that ensure viability and high germination standards. Trials were conducted with seeds at different stages of ripeness. Seed batches were germinated in various locations on Madeira to test the influence of soil and climatic conditions. Seed germination was also tested in greenhouses and on different substrates. Subsequently, seeds underwent different pre-germination treatments and were placed in phytoclimatic chambers to study associated dormancy. Finally, changes in the biochemical composition of the seeds during germination and the role of two metabolic markers were assessed. Germination success varied by species. Vaccinium padifolium showed the best germination rate in seeds at a more advanced stage of ripeness, with a success rate exceeding 75% in phytoclimatic chamber. Laurus novocanariensis had the highest germination percentage in the field and greenhouse, ranging from 76.67% to 90%. Myrica faya and Teline maderensis achieved higher rates in the laboratory, over 66% and 71%, respectively. In terms of biochemical composition, the four species showed the highest starch concentration at the most advanced stage of ripeness. Sugar concentrations were markedly low in most samples. Lipids and crude protein exhibited a low rate of mobilization during germination. Laurus novocanariensis showed the sharpest reduction in soluble sugars, lipids, and protein during germination (84.43%, 28.41%, and 17.63%, respectively), while Myrica faya exhibited the highest starch mobilization (81.65%). Regarding metabolic markers, malate dehydrogenase showed increased enzymatic activity during germination and peroxidase activity was low in all samples.
Description
Keywords
Germinação Substratos Condições edafoclimáticas Pré-trataments Composição bioquímica Metabolismo celular Germination Substrates Edaphoclimatic conditions Pre-treatments Biochemical composition Cell metabolism Bioquímica Aplicada . Faculdade de Ciências Exatas e da Engenharia