Seed germination and seedling growth of Alnus maritima from its three disjunct populations

Genotypic variation and horticultural potential of Alnus maritima [Marsh.] Nutt, (seaside alder), a large shrub or small tree found naturally in only three small, disjunct populations, have not been studied. We examined effec ts of population of origin and environment on seed germination and growth a nd morphology of seedlings. The first experiment showed that 6 weeks of col d stratification optimized germination of half-sibling seeds from Oklahoma at 73.2%, When this treatment was applied to multiple groups of half-siblin gs from all populations in a second experiment, seeds from Oklahoma had a h igher germination percentage (55.0%) than seeds from Georgia (31.4%) and th e Delmarva Peninsula (14.7%). In a third experiment, morphology and growth of multiple groups of half-siblings from all three populations were compare d in one environment. Leaves of seedlings from Oklahoma were longer (12.8 c m) and more narrow (2.15 length to width ratio) than leaves of seedlings fr om Georgia (12.0 cm long; ratio = 1.76) and the Delmarva Peninsula (11.6 cm long; ratio = 1.86), Seedlings from Oklahoma and Georgia accumulated dry w eight at higher rates (181 and 160 mg.d(-1), respectively) than seedlings f rom Delmarva (130 mg.d(-1)), while seedlings from Oklahoma and Delmarva wer e more densely foliated (0.72 and 0.64 leaves and lateral shoots per centim eter of primary stem, respectively) than those from Georgia (0.46 per cm), These differences indicate genetic divergence among the three disjunct popu lations and the potential to exploit genetic variation to select horticultu rally superior A. maritima for use in managed landscapes.