Influence of aerial seed banks on germination response in three desert plant species

Aims To determine if the germination response of desert plant species to a period of aerial storage in field conditions(i.e.mature seeds that remain attached to the parent plant)is comparable to seeds harvested at maturity and stored in ambient laboratory conditions,to better understand the role of aerial seed bank in the germina-tion ecology of desert plants,using one annual and two perennial species.Methods Seeds of three desert plants(Anastatica hierochuntica,Blepharis ciliaris and Scrophularia deserti)that matured in June 2014,were collected from wild plants in June and November 2014,and ger-minated under two photoperiods(0,12 hours light)and three ther-moperiods(night/day temperatures of 15/25,20/30 and 25/35°c).Important Findings Seeds of B.ciliaris and S.deserti had significantly higher germination percentages when harvested and stored for five months,compared to being stored in the aerial seed bank.Germination percentages of these two species increased with decreasing temperature and in the presence of light.These results indicate that these species use a com-bination of aerial and soil seed banks to maintain a percentage of viable seeds through favourable germination periods.Germination percentages of A.hierochuntica were high under all tested circum-stances,indicating that this species relies mainly on the aerial seed bank to maintain a percentage of viable seeds through favourable germination periods.This study shows that the population survival strategies of an aerial seed bank are species-specific.These results have practical implications for conservation and habitat restoration for these species,and also for their propagation since early collec-tion of mature fruits and ex situ storage will result in greater germi-nation percentages of some species.