Multiple dormancy and maternal effect on Miconia ferruginata (Melastomataceae) seed germination, Serra de Caldas Novas, Goiás, Brazil

Abstract

-(Multiple dormancy and maternal effect on Miconia ferruginata (Melastomataceae) seed germination, Serra de Caldas Novas, Goiás, Brazil). Species with mostly asexual reproduction are interesting subjects for germination studies since variation would be more easily linked to environmental factors. Miconia ferruginata DC. is an apomictic treelet in Brazilian cerrado areas on rocky outcrops. Germination of seeds collected from individuals occurring in the Serra de Caldas Novas State Park, Goiás, was studied in three experiments under controlled conditions. Germination characteristics differed among individuals and were correlated with altitude and soil Al content. Seeds from plants growing at lower altitudes, with lower soil aluminium content, presented malformed seeds with absence of embryo which rendered lower, but better synchronized germination. The nested analysis showed that from the total variance, 78.14% for germinability, 54.56% for uncertainty of the germination process, and 68.30% for the quantity of seeds without embryo was attributed to the altitudinal effect. Individuals nested within altitude contributed up to 16.93% for the total variance. It means that there is low variability among individuals of the same altitude and high variability among individuals from different points of the slope, making clear that for the studied population the environmental effect is stronger than the genetic component to determine the seed quality. The testa of the seeds provides a mechanical dormancy which seems to be associated also with phenolic compounds, which help to disperse germination through time. Photoblastism was also registered for seeds of this species.Key words -altitudinal gradient, campo rupestre, cerrado, dormancy, tropical savanna RESUMO -(Dormência múltipla e efeito maternal na germinação de sementes de Miconia ferruginata (Melastomataceae), Serra de Caldas Novas, Goiás, Brasil). Espécies com reprodução principalmente assexuada são interessantes para estudos de germinação, uma vez que a variação pode ser mais facilmente associada a fatores ambientais. Miconia ferruginata DC. é um arbusto apomítico de cerrado rupestre brasileiro. A germinação de sementes coletadas no Parque Estadual da Serra de Caldas Novas, Goiás foi estudada em três experimentos sob condições de laboratório. O processo de germinação diferiu entre os indivíduos, correlacionando-se com altitude e teor de Al do solo. Sementes oriundas de plantas crescendo nas menores altitudes, com menor teor de alumínio no solo, apresentaram sementes mal formadas, com ausência de embrião, resultando em baixa germinabilidade, mas maior sincronia de germinação. A análise hierárquica mostrou que 78,14% da variabilidade na germinabilidade, 54,56% na incerteza e 68,30% na quantidade de sementes sem embrião foram atribuídos ao efeito altitudinal. Indivíduos agrupados dentro de altitude contribuíram até 16,93% para a variância total. Isto significa que há baixa variabilidade entre indivíduos da mesma altitude e alta variabilidade entre indivíduos de ...

Sexual ratio and floral biology of the dioecious Neea theifera Oerst. (Nyctaginaceae) in a cerrado rupestre of central Brazil

“…In the studied area, N. theifera trees were mainly found on these sloped sites, which possibly aff ected the plant growth pattern along the altitudinal-soil gradient resulting in smaller trees at higher altitudes. In this site, Mendes-Rodrigues et al (2010) found an increase in soil acidity and aluminum content toward higher altitudes and an inverse trend for some other minerals. It is important to note that in this study the authors evaluated an altitudinal gradient smaller than ours (from 795 to 907 m a.s.l.…”

“…Th e later is defi ned as subtypes of shrub and arboreal formations with litholic or rocky soils (sensu Ribeiro & Walter 1998). Th e crown cover ranges from 5 to 20% occurring among rock outcrops on small patches formed by the decomposition of sandstone and quartzite, which is generally nutrient poor, acidic and has low organic matter content (Ribeiro & Walter 1998;Mendes-Rodrigues et al 2010). In PESCAN, Neea theifera is predominantly distributed on hillsides within cerrado rupestre where it is relatively more abundant than in cerrado sensu stricto (Silva et al 2002;Lima et al 2010;Lopes et al 2010).…”

“…In PESCAN, Neea theifera is predominantly distributed on hillsides within cerrado rupestre where it is relatively more abundant than in cerrado sensu stricto (Silva et al 2002;Lima et al 2010;Lopes et al 2010). In cerrado rupestre (at PESCAN) the soil shows decreasing fertility and a progressive increase of acidity, aluminum content and saturation as the elevation increases (Mendes-Rodrigues et al 2010).…”

“…Individuals from higher altitudes were smaller than individuals from the lower parts of the gradient for both genders. Th e soil from cerrado rupestre is naturally shallow, and poor in organic matter and nutrients (Ribeiro & Walter 1998;Mendes-Rodrigues et al 2010). When it comes to hillside areas, soils from higher …”

Germinação de sementes e emergência de plântulas de <i>Anadenanthera colubrina</i> (Vell.) Brenan var. <i>cebil</i> (Griseb.) Altschut, Fabaceae, estabelecida em fragmentos florestais do Cerrado, MG

“…Entre 1 e 5 dias após a semeadura, foram registrados 40% de germinação ou emergên-cia, sendo o restante espalhado ao longo de 25 dias. A falta de homogeneidade registrada para os processos de germinação e emergência de Anadenanthera colubrina parece ser um comportamento comum entre as espécies nativas e isso foi detectado também para núculas de Anacardium humile A. St. -RODRIGUES et al, 2010) e para a maioria das 19 espécies florestais estudadas por Dorneles (2010). Esta heterogeneidade pode estar refletindo as oscilações climáticas e ecológicas que ocorreram durante os eventos de polinização, formação e maturação dos frutos e sementes, conforme apontou Garwood (1983).…”