Light and temperature requirements for germination of seeds of Aechmea nudicaulis (l.) Griesebach and Streptocalyx floribundus (Martius ex Shultes f.) Mez (Bromeliaceae)

Abstract

RESUMO -[Requerimentos de luz e temperatura para a germinação de sementes de Aechmea nudicaulis (L.) Griesebach e Streptocalyx floribundus (Martius ex Schultes F.) Mez (Bromeliaceae)]. Sementes de A. nudicaulis e S. floribundus foram coletadas em uma restinga em Presidente Kennedy (ES). Esta comunidade arenosa caracterizase pela presença de moitas de vegetação separadas por areia nua ou com rala cobertura vegetal. Para examinar a capacidade das sementes em germinar nas distintas situações microclimáticas presentes neste ambiente, foram conduzidos, em laboratório, experimentos de germinação sob diferentes condições de temperatura e luminosidade. Sementes de A. nudicaulis não germinaram no escuro, mas sob luz vermelha atingiram alta germinabilidade (≥90%) entre 15 e 40°C. Sementes de S. floribundus germinaram no escuro apenas a 40ºC (22,5%), enquanto na luz, a germinabilidade foi acima de 90% entre 15 e 30ºC. Para ambas as espécies a velocidade de germinação foi máxima a 25ºC. Para as duas bromélias, temperaturas alternantes (20/30ºC) resultaram em alta germinabilidade (≥92,5%) apenas na luz. Sementes mantidas a 20/30°C no escuro foram posteriormente transferidas para luz, resultando numa alta germinabilidade (>89%) para ambas as espécies. Nenhuma semente germinou a 20/50ºC, perdendo a viabilidade após 720h de incubação. As sementes mostraram-se fotoblásticas positivas e não toleraram altas temperaturas. Em condições naturais, a germinação de A. nudicaulis e S. floribundus parece ser dependente da presença de luz e de cobertura vegetal, sendo limitada em condições de soterramento e em sítios que apresentam temperaturas do solo elevadas. Palavras-chave -Aechmea nudicaulis, Streptocalyx floribundus, restinga, germinação, temperaturaABSTRACT -[Light and temperature requirements for germination of seeds of Aechmea nudicaulis (L.) Griesebach and Streptocalyx floribundus (Martius ex Schultes F.) Mez (Bromeliaceae)]. Seeds of A. nudicaulis and S. floribundus were collected in a restinga located at Presidente Kennedy (ES, Brazil). This sandy community is characterized by the presence of patches of vegetation interspersed by open areas with a sparse plant covering. In order to evaluate the capacity of A. nudicaulis and S. floribundus to recruit individuals from seeds in the distinct microclimates generated by this heterogeneous plant covering, experiments were conducted in laboratory to test the effects of light and temperature on the germination for both species. Seeds of A. nudicaulis were unable to germinate in darkness but they achieved high germinability (≥90%) from 15 to 40°C under red light. Seeds of S. floribundus germinated in darkness only at 40ºC (22.5%), whereas the germinability was high (≥90%) from 15 to 30ºC under Pinheiro & Borghetti: Light and temperature requirements for germination of seeds light. For both species, the germination rate was highest at 25ºC. For these bromeliads, alternating temperature (20/30ºC) promoted high germinability (≥92.5%) only under red light. The seeds at 20/30°C in darkness w...

Micropropagation and in vitro conservation of Neoglaziovia variegata (Arr. Cam.) mez, a fiber producing bromeliad from Brazil

“…According to Socolowski and Takaki (2004) seeds with phytochrome A can germinate under light and darkness conditions and if just phytochrome B is present the seeds germinate only in presence of light. Some native bromeliads that occur in the Restinga ecosystems produce seeds that require light for germination (Pinheiro and Borghetti 2003). The percentage of germination obtained in caroá was, however, similar to the results obtained with Ananas ananassoides (Baker L. B. Sm) (91.2%), in the presence of light with a 12 h photoperiod (Figueiredo et al 2003) and with V. gigantea (93,9%), with a 16 h photoperiod (Droste et al 2005).…”

Germination of Ocotea pulchella (Nees) Mez (Lauraceae) seeds in laboratory and natural restinga environment conditions

“…Although some studies have focused on ecophysiological aspects of Restinga species (Scarano et al, 1997;Pinheiro and Borghetti, 2003), much work is still necessary -particularly for those related to the initial plant development stages -to understand forest dynamics and contribute to recovery and conservation actions of the Restinga biome. Ocotea pulchella (Nees) Mez (Lauraceae) is a tree growing up 4 to 30 m in height; zoochoric; occurring frequently in Restinga forest; with high IVI (importance value index) in non-flooded forests in the south littoral of São Paulo State and the north of Paraná State (Carrasco, 2003;Sugiyama, 2003;Silva and Britez, 2005).…”

Habitat utilization and CAM occurrence among epiphytic bromeliads in a dry forest from southeastern Brazil

“…Some studies have demonstrated that, for some bromeliad species with terrestrial and epiphytic habit, a continuous humidity supply is one of the most important conditions for seed germination. Such results were obtained with Aechmea nudicaulis and A. fl oribunda, which occur on the soil of drier regions of shrub restinga (Pinheiro & Borghetti 2003), where their seeds need at least four days in an embedded state to germinate. For strictly epiphytic plants, Callaway et al (2002) demonstrated that, in subtropical forests of the United States, the main factor that increases the abundance of Tillandsia usneoides on some tree trunks is their capacity to retain water.…”