Dimorphic cypsela germination and plant growth in Synedrella nodiflora (L.) Gaertn. (Asteraceae)

Abstract

Synedrella nodiflora is a weed species that has dimorphic cypselas: winged peripheral and lanceolate shaped central. The aim of this work is to describe the reproductive capability by measuring dimorphic cypselas morphology, imbibition rates and germinative patterns under temperature, light quality and water availability gradients, and compare the plant growth between two light treatments. The central cypselas were lighter, longer and its pappi were more elongated than the peripheral ones, favoring its dispersion. Neither type had deep dormancy and both of them germinated with the same pattern under the optimum conditions. Both cypselas showed higher germinability in temperatures between 25 and 30 °C, under white light and high water availability, although there are some differences between the types, mainly at dark treatments. Plants grown in direct sunlight accumulated more biomass, allowing for higher plant development and inflorescence production, although shaded light plants capitulum had a higher central: peripheral ratio than the direct sunlight treatment. S. nodiflora cypselas germinate better in unfiltered light places, although the plants are adapted to shady conditions. The species showed high germination potential over a wide range of environmental conditions, as well as fast plant development. All of these features favor distribution in environmental sites.

High Connectivity Among Synedrella nodiflora Populations in Java Island Based on Intergenic Spacer atpB-rbcL

“…Cypselas germinate more easily in high light intensity than they do in the dark or shaded areas. Nevertheless, other environmental factors have no significant influence on cypsela germination, so that S. nodiflora can grow well in a very wide range of environmental conditions (Souza Filho & Takaki, 2011). Otherwise, the pollens can also be accidentally carried in seeds of crops after harvesting if S. nodiflora grows in a crop field.…”

“…In other words, in every individual there can be 3,000 fertile seeds ready to germinate as they are not subjected to dormancy. It can grow in a wide range of altitudes, from 0 to approximately 1,000 m above sea level (Dwiati et al, 2003), while its life cycle varies from 120 to 150 days (Souza Filho & Takaki, 2011).…”

The necessity for testing germination of fresh seeds in studies on diaspore heteromorphism as a life-history strategy

“…A perusal of papers on fruit/seed heteromorphism published more recently than those referenced in Table 1 shows that the practice of not testing fresh seeds is being continued (e.g. Atia et al , 2011; Souza Filho and Takaki, 2011), as is the practice of testing fresh seeds in such studies (Cao et al , 2012; Wang et al , 2012).…”

Germination constraints of dicarpic cypselae of Bidens pilosa L.

“…The dimorphic behavior of Bidens pilosa has been previously reported in other works (Forsyth and Brown, 1982;Rocha, 1996;Amaral and Takaki, 1998); however, our effort was the first to investigate the nature of the germination constraints on cypselae types. Despite the fact that the pericarp may not influence the dicarpic seed germination (Souza Filho and Takaki, 2011), there are species in which different mechanical constrains are imposed by the pericarp (Imbert, 2002). Still, few reports presented chemical constraints on the germination of heterocarpic species.…”