Aspectos fenológicos e germinação de sementes de quatro populações de Eupatorium vauthierianum DC. (Asteraceae)

Abstract

Através do estudo do florescimento e da frutificação de quatro populações de Eupatorium vauthierianum, na região de Paranapiacaba, observou-se uma defasagem de florescimento de cerca de 20 dias entre as populações mais precoces e as mais tardias. Para as mais precoces, os capítulos estavam com flores em diferentes estádios de desenvolvimento em maio e a plena frutificação ocorreu em meados de junho. Decorreram cerca de 55 dias da fase de botão floral até a de fruto maduro. O número de frutos (aquênios) por capítulo variou de 10 a 26 e a porcentagem de aquênios férteis por capítulo variou de 5,5 a 100%. Através do estudo da germinação observou-se variação na capacidade germinativa, tanto dentro como entre as populações estudadas. A temperatura de 20°C mostrou-se mais eficiente na promoção da germinação que 25°C e 30°C, o mesmo ocorrendo com o fotoperíodo de 12 horas quando comparado ao tratamento de escuro.<br>Observations of flowering, fruit development and seed germination of four populations of E. vauthierianum in Paranapiacaba region showed a discrepancy of about 20 days in the time of flowering. In May, the earliest populations presented heads with flowers in different stages of development and frutification occurred in mid-June. The complete development from flower buds to ripe fruits lasted approximately 55 days. The number of fruits per head varied from 10 to 26 and the percentage of fertile fruits from 5.5 to 100%. Seed germination assays showed variations in the germination capability both within and among populations. Germination was shown to be greater at 20°C than 25°C and 30°C. Moreover, 12 hour photoperiod was shown to be more effective than full darkness for seed germination

Community structure and comparative analysis of the woody component of a cerrado remnant in Southeastern Brazil

“…However, the studied area showed to be highly distinct as Asteraceae is its richest family, a fact that was not observed in previous inventories performed in cerrados of Botucatu region (Silberbauer-Gottsberger & Eiten 1987, Bicudo et al 1996, which present Fabaceae, Myrtaceae in such position. This feature may be related to the conservation state of the studied cerrado considering that among the inventoried Asteraceae species Eupatorium vauthierianum (Maluf & Wizentier 1998) and Vernonia polyanthes (Lorenzi 2008) are reported as colonizer species and Piptocarpha axilaris (Lorenzi 2009) and P. rotundifolia (Lorenzi 1998) are reported as pioneers in cerrado and forest areas.…”

“…This species had an IV of 0.65 in a cerradão area in Corumbataí, São Paulo State (Cesar et al 1988). However, it was abundant in a region of poor and acid soil, in Santo André (São Paulo State), which underwent anthropic interferences, and was considered an r-strategist colonizer species (Maluf & Wizentier 1998). Thus, its occurrence may evidence the regeneration phase now experienced by the studied area which, although preserved since year 2001, might have suffered anthropic interferences in the past since it is located beside a highway and an abandoned reforestation area.…”

Seed germination of Chresta sphaerocephala DC. and Lessingianthus bardanoides (Less.) H. Rob. (asteraceae) from Cerrado

“…Neverthless, only Sassaki et al (1999) and Velten and Garcia (2005) related the germination ratio to vegetative production. A common phenomenon in the family Asteraceae and directly related to germination rate is the significant amount of seed production, although many of them are embryoless (Sassaki et al, 1999), which has been confirmed by others (Achutti, 1978;Sajo and Menezes, 1986;Maluf and Wizentier, 1998;Sassaki et al, 1999;Bertasso-Borges and Coleman, 2005;Velten and Garcia, 2005;Tonetti et al, 2006); this although common, has not been fully elucidated yet, and since it affects the seed germination rates, it must always be considered in germination trials of the family Asteraceae. In order to enhance the knowledge on the herbaceous-subshrubby flora of the family Asteraceae in the São Paulo state Cerrado, thus contributing for its preservation, the aims of this work were: (i) to study the effects of different temperature conditions on the germination of L. bardanoides and C. sphaerocephala seeds; (ii) to compare the germination rates of both the species, and (iii) to estimate the occurrence of embryoless seeds for each species.…”

Germinação e qualidade de sementes de Adenostemma brasilianum (pers.) cass., Asteraceae nativa de sub-bosque de Floresta Atlântica

“…Ferreira et al (2001) estudaram sementes de 13 espécies, de vários gêneros, e apenas quatro mostraram porcentagens de germinação superiores a 50%. As baixas porcentagens de germinação têm sido explicadas pelo requerimento de condições ambientais específicas (LAWRENCE, 1980) ou como reflexo dos elevados percentuais de sementes sem embrião, difíceis de serem eliminadas dos experimentos por se apresentarem morfologicamente perfeitas (FIGUEREDO, 1975;CLAMPITT, 1987;MALUF;WIZENTIER, 1998;FERREIRA et al, 2001; este estudo).…”

“…O fotoblastismo positivo é muito comum entre as asteráceas (BASKIN; BASKIN, 1979;GRIME et al, 1981;LADEIRA et al, 1987;MALUF;WIZENTIER, 1998;FERREIRA et al, 2001;VELTEN;GARCIA, 2005), e os resultados deste estudo confirmaram essa tendência. Sheldon (1974) (FIGUEREDO, 1975;FORSYTH e BROWN, 1980;GRIME et al, 1981;BORGHTTI et al, 2002).…”