Seed Size Variation and Its Effects on Seedling Growth in Agropyron psammophilum

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Abstract
Seed size variation and its effects on germination and seedling growth were examined in seeds collected from a population of Agropyron psammophilum on a sand dune system along Lake Erie. Seed size varied from 0.8 to 5.1 mg per seed. Total germination of seeds was not affected by seed size, but large seeds germinated significantly faster than did small seeds. The leaf area and absolute dry weight of 10-20-d-old seedlings from large seeds were significantly higher than those from small seeds. These differences disappeared in seedlings harvested 30 and 40 d after emergence owing to a higher initial relative growth rate in seedlings from small seeds but reappeared in seedlings harvested 50 and 60 d after emergence. The relative growth rate of seedlings from both small and large seeds decreased with time. However, the time of decrease was greater in seedlings from small seeds, which eventually resulted in seedlings of smaller size than those from large seeds at later stages of development.