Relationships between seed germination requirements and ecophysiological characteristics aid the recovery of threatened native plant species in Western Australia.

Summary One of the foremost technical issues addressed in reintroduction and restoration projects is the feasibility of establishing living plants. To advance the recovery process, the germination requirements of 201 threatened Western Australian seed-bearing taxa representing a range of life forms, families and ecophysiological characteristics were studied. Procedures used to stimulate germination in otherwise dormant seed involved pretreatment using thermal shock, scarification, seed coat removal, soaking in an aqueous smoke solution and/or additions of the growth hormone gibberellic acid (GA₃ ). Sixty-one taxa germinated under the basic trial conditions of light (12- h photoperiod), temperature (constant 15°C) and moisture, without additional pretreatments. These taxa were generally those with canopy-stored seeds in the families Proteaceae and Casuarinaceae, and small-seeded taxa in Myrtaceae. Taxa with soil-stored seeds required single or multiple cues to stimulate germination. Seeds in the families Fabaceae and Mimosaceae were dependent on cracking of the seed coat, mechanically through nicking of the testa or through thermal shock, as were several non-leguminous species of the Sterculiaceae and Liliaceae. Complete or partial removal of seed coats, in conjunction with GA₃ enhanced germination percentage in some taxa of the Myoporaceae, Lamiaceae and Myrtaceae. Application of GA₃ also enhanced germination percentage in members of the Epacridaceae. Several taxa previously stimulated by aqueous smoke solutions were equally responsive to additions of GA₃ after complete seed coat removal. In general, species with seed weights greater than 10 mg germinated better under a range of conditions than those with lighter seeds. There was no difference in germinability between resprouter and seeder species, and no obvious relationship between seed weight and germination rate. In the light of previous studies these results... [ABSTRACT FROM AUTHOR]