Effects of maternal environmental factors on physical dormancy of Astragalus nitidiflorus seeds (Fabaceae), a critically endangered species of SE Spain

摘要

The viability and seed dormancy of the critically endangered species Astragalus nitidiflorus were tested during eight consecutive years (2006-2013) in order to determine if the high physical seed dormancy described in a previous study is affected by annual or seasonal environmental conditions. Also, the effects of maternal factors - such as fruit position in the inflorescence or seed position in the fruit, the age of the mother plants, and water stress - on seed viability and dormancy were tested. In order to determine the variation in the degree of germinability between years, ripe seeds were harvested each July from 2006 to 2013 and their viability and dormancy were tested. Moreover, in 2013 new seeds were collected to check the effects of the maternal factors mentioned above. A trial with potted plant in greenhouse was performed to corroborate the observed field data about the effect of water stress suffered by the mother plant on seed dormancy. The results show a high variability over the years in the physical dormancy of A. nitidiflorus seeds because maternal environmental factors such as drought or mother plant age influence the proportion of seeds that enter dormancy. This in turn determines the proportion of seed that becomes part of the seed bank each year and also the age structure of the natural population. The conservation programs for this critically endangered species should consider these results to implement measures to prevent the extinction of the species. (C) 2015 Elsevier GmbH. All rights reserved.