Conservation potential, viability protection and breaking seed dormancy of some tree and shrub species of Iran

The seeds tolerating drying and moisture content as less as 5% are known as orthodox seeds. The seeds of tree and shrub species growing in temperate zones belong to this group. In this investigation, seeds of 32 species, collected from natural habitats, were evaluated. The seed samples were processed for cleaning and then seed health and breaking seed dormancy were tested. The dormancy treatments included: pre-germination cooling test with different times, chemical and hormonal (GA3) agents with different concentrations and duration, mechanical and chemical scarification with two germination beds (Petri dishes with paper filter and pots containing sands). The trend of seed viability reduction was different among the study species. The seeds of Amigdalus scoparia and many pine species had high seed viability (44 to 88%) after twenty years but the species with small seeds like Alnus glutinosa, Fraxinus and Haloxylon had lower seed viability. The cause of decreased seed viability was related to the storage materials and their genotype. It was concluded that seed size and seed storage behavior would be useful as important factors to determine seed regeneration.