Welchen Einfluss haben Temperatur und Azidität der Bodenlösung auf die Keimungsbiologie ausgewählter xerothermer Graslandsarten?

Abstract

Partzsch, M.: What influences do temperature and acidity of soil solution have on the germination biology of four typical xerothermic grassland species? – Hercynia N.F. 41 (2008): 239 -252.Germination represents the most sensitive stage in the life cycle of any plant species. For this study we investigated which temperature and light conditions favoured diaspore germination most. In addition we monitored the influence of pH on this process. We chose Calluna vulgaris, Filipendula vulgaris, Jurinea cyanoides and Seseli hippomarathrum as target species as they are important members of the xerothermic grasslands that exist under the typically dry climatic conditions of Central Germany (Döring & Borg 2008) They also count as indicator species of acidic or alkaline conditions (Ellenberg 2001, Rothmaler et al. 2005). The experiment was started after collection of seeds in autumn 2003. Results show that all four species germinate most successfully and quickest under a temperature-light regime of 20 °C light / 10 °C dark. Under cold conditions (8/4 °C) Filipendula vulgaris germinated to a minor degree, while the other species showed no germination at all. At high temperatures (32/20 °C) the germination of both Jurinea cyanoides and Seseli hippomarathrum were greatly reduced. Calluna vulgaris and Filipendula vulgaris showed reduced germination velocity, but almost the same final germination success as at 20/10 °C. In another experiment the effect of various pH-values (3.5, 4.5, 5.5, 6.5, 7.5 and 8.5) on germination behaviour was tested under optimal germination conditions (20/10 °C; in April 2004). Results showed that the diaspores of all four species germinated a broad range of pH-levels and showed no significant differences between the final germination and velocity (results of ANOVA); don’t mean that they are indicators of acid or alkali soil conditions. As the experiment of the influence of temperature on germination was carried out in autumn 2003 and the pH-value experiment in the following spring (2004), we found that the germination of Jurinea cyanoides was reduce in spring. Filipendula vulgaris showed no significant differences in the final germination or in germination speed between autumn and spring. Calluna vulgaris and Seseli hippomarathrum show no significant differences in final germination, but diaspores germinated faster in spring. The germination behaviour and the size and morphology of the diaspores allowed us to come to conclusions about the species’ types of seed bank: Filipendula vulgaris, Jurinea cyanoides and Seseli hippomarathrum build transient or short-term-persistent seed banks, while Calluna vulgaris develops a more long-term-persistent type.