Aspectos germinativos de espécies do campo úmido: uma formação vegetacional do Cerrado
Carregando...
Data
2019-02-08
Autores
Luscenti, Renato Santana
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
O Cerrado é o segundo maior bioma do Brasil em extensão. Sua vegetação apresenta variações consideráveis, ocorrendo desde fitofisionomias florestais e savânicas, até as campestres. Dentre essas, os campos úmidos são classificados como fisionomias campestres, cuja vegetação se estabelece em solos alagados (deficientes em oxigênio). Nos campos úmidos a vegetação é aberta, com presença de arbustos e subarbustos entremeados no estrato herbáceo, havendo incidência direta de luz solar e ampla variação de temperatura. Os campos úmidos têm grande importância na manutenção do regime dos rios e na recarga das águas subterrâneas, desempenhando assim importantes serviços ecossistêmicos. Estudos a respeito deste ambiente são escassos, principalmente relacionados à germinação. Nesse contexto, avaliamos a germinação de 11 espécies de campo úmido, na presença e ausência de luz, em temperatura constante (25°C) e alternada (30-20°C), e sob alagamento (sementes boiando e submersas na água), sendo o alagamento o principal filtro ambiental no campo úmido. Os resultados mostraram que a maioria das espécies dependeu de luz para germinar, sendo indiferente aos regimes de temperatura testados. Todas as espécies germinaram boiando e a maioria germinou mesmo quando as sementes foram mantidas em submersão (hipóxia). As sementes das espécies que não germinaram submersas mantiveram viabilidade, com exceção de Arthropogon villosus. Pode-se concluir que as plantas do campo úmido estão adaptadas ao alagamento, principalmente por possuírem sementes leves que são capazes de boiar e germinar nesta condição.
The Cerrado is the second largest biome in Brazil in extension. Its vegetation presents considerable variations, occurring from forest and savanna phytophysiognomies, as grasslands. Among these, there are wet grasslands whose vegetation occurs in flooded soils (with oxygen deficiency). In wet grasslands the vegetation is open, with the presence of shrubs and sub-shrubs interspersed in the herbaceous stratum, with direct incidence of sunlight and a wide temperature variation. The wet grasslands are of great importance in maintaining the rivers regime and recharge of groundwater, thus playing important ecosystems services. There are few works about this environment, especially related to germination. In this context, we evaluated the germination of 11 species of wet grasslands under presence and absence of light, in constant (25ºC) and alternating (30-20 ºC) temperature regimes and under flooding (seeds floating and submerged in water), being the flooding the main environmental filter in the wet grasslands. The results showed that most of the species depended on light to germinate, being indifferent to the temperature regimes tested. All species germinated floating and most germinated even when submerged (hypoxia condition). The seeds of species that did not germinate submerged maintained their viability, except for Arthropogon villosus. It can be concluded that wet grasslands plants are adapted to flooding, mainly because they have light seeds that are able to float and germinate in this condition
The Cerrado is the second largest biome in Brazil in extension. Its vegetation presents considerable variations, occurring from forest and savanna phytophysiognomies, as grasslands. Among these, there are wet grasslands whose vegetation occurs in flooded soils (with oxygen deficiency). In wet grasslands the vegetation is open, with the presence of shrubs and sub-shrubs interspersed in the herbaceous stratum, with direct incidence of sunlight and a wide temperature variation. The wet grasslands are of great importance in maintaining the rivers regime and recharge of groundwater, thus playing important ecosystems services. There are few works about this environment, especially related to germination. In this context, we evaluated the germination of 11 species of wet grasslands under presence and absence of light, in constant (25ºC) and alternating (30-20 ºC) temperature regimes and under flooding (seeds floating and submerged in water), being the flooding the main environmental filter in the wet grasslands. The results showed that most of the species depended on light to germinate, being indifferent to the temperature regimes tested. All species germinated floating and most germinated even when submerged (hypoxia condition). The seeds of species that did not germinate submerged maintained their viability, except for Arthropogon villosus. It can be concluded that wet grasslands plants are adapted to flooding, mainly because they have light seeds that are able to float and germinate in this condition
Descrição
Palavras-chave
Deficiência de oxigênio, Alagamento, Luz, Temperatura, Germinação