Seed size effect on seedling growth under different light conditions in the clonal herb Ligularia virgaurea in Qinghai Tibet Plateau
不同光照处理下青藏高原克隆植物黄帚橐吾(Ligulariavirgaurea)种子大小对其幼苗生长的影响

We studied the influence of seed size on germination, seedling growth, and seedling responses to light in Ligularia virgaurea, a clonal herb native to the Qinghai Tibet Plateau. (1) Under unshaded conditions, large seeds had significantly (p<0.01) higher rates of germination than did small seeds. Both large and small seeds showed significantly reduced levels of germination under shaded (by shadecloth) conditions. The magnitude of this effect was greater for small seeds than for large seeds. Germination of small seeds (1.75 mg) was reduced by one eighth, while germination of large (2.80mg) seeds was only reduced by one eleventh. (2) Seedlings from large seeds had significantly higher rates of biomass accumulation (g d-1)than did seedlings from small seeds. This, combined with larger initial masses gave seedlings from large seeds significantly greater total biomass after 60 days of growth. Seedlings from large and small seeds also differed in biomass allocation. After 60 days of growth (under both shaded and unshaded conditions), seedlings from larger seeds had proportionally larger root mass and proportionally smaller leaf mass than did seedlings from small seeds. (3) Seedlings from small seeds have higher relative growth rates (RGR; g g-1 d-1) than do seedlings from large seeds, under both shaded and unshaded conditions. By contrast, there was no significant difference between leaf area ratio (LAR); specific leaf area (SLA) or leaf weight ratio (LWR) between seedlings from small vs large seeds. RGR, LAR, SLA and LWR were all significantly higher in seedlings grown under shaded conditions than in seedlings grown in full light.