Germination Responses to Water Potential in Neotropical Pioneers Suggest Large-seeded Species Take More Risks
Open Access
- 7 October 2008
- journal article
- research article
- Published by Oxford University Press (OUP) in Annals of Botany
- Vol. 102 (6), 945-951
- https://doi.org/10.1093/aob/mcn186
Abstract
In neotropical forests, very small-seeded pioneer species (Ochroma pyramidale (seed mass 5·5 mg) had a time to 50 % germination (T50) of 2·8 d and a median base potential for germination (ψb50) of −1·8 MPa while Clidemia quinquenervia (seed mass 0·017 mg) had a T50 of 17·6 d and ψb50 of −1·1 MPa. These data suggest that small-seeded species germinate only in comparatively moist microsites, such as small canopy gaps, which may reduce the risk of drought-induced mortality. Conversely, large-seeded species are able to germinate in the drier environment of large gaps, where they benefit by enhanced seedling growth in a high irradiance environment. The positive association of seed size and canopy gap size for optimal seedling establishment is maintained by differential germination responses to soil water availability coupled with the scaling of radicle growth rate and seed size, which collectively confer greater drought tolerance on large-seeded species.Keywords
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