Dormancy and germination of dimorphic achenes have been compared within and between numerous species of Asteraceae, whereas only a few such comparisons have been made with trimorphic achenes. Garhadiolus papposus is an annual ephemeral species of disturbed desert habitats that produces three kinds of achenes that differ in size, morphology, pappus development and germination requirements. Fresh central achenes germinated to 10-21% in light at 15/2 and 20/10 °C, while intermediate and peripheral achenes germinated to < 5%. Germination was enhanced by excising the embryo in peripheral but not in intermediate achenes. For peripheral and intermediate achenes, pericarps and/or phyllaries did not inhibit germination of isolated embryos, indicating that water-soluble germination inhibitors were not present in these structures. For central and intermediate achenes, germination percentage increased with duration of dry storage at room temperature. Darkness decreased germination of central and intermediate achenes, while peripheral ones, which were viable, did not germinate at any condition. These data show that 1) the three morphs differ in germination requirements, and 2) difference in germination may be caused by low growth potential of the embryo and mechanical resistance (to embryo growth) of the thick pericarp and/or lignified phyllary.
|Number of pages||9|
|Journal||South African Journal of Botany|
|State||Published - Aug 2009|
Bibliographical noteFunding Information:
We thank Chenyi Lin for her comments on an early draft of this manuscript, Lixia Tan for drawing a graph presented in the manuscript and Rongming Qu for collection of seeds. Funding was provided in part by the Projects on the Research and Development of High Technology of Xinjiang Uygur Autonomous Region, China (grant no. 200810102), the Construction of Scientific and Technological Platforms Project from the Chinese Ministry of Science and Technology (no. 2005DKA21006) and the National Natural Science Foundation of China (no. 90302004).
- Garhadiolus papposus
- Junggar Desert
- Trimorphic achenes
ASJC Scopus subject areas
- Plant Science