Effect of selective abortion on seed germination and post-germination performance of offspring

Hermaphroditic angiosperms, especially outcrossers, generally produce many more flowers and ovules than they can mature into fruits and seeds. One of the several hypotheses to account for the production of 'excess' flowers is selective abortion, which has been shown to increase offspring quality in plants. Our primary aim was to review the literature on the effects of selective abortion on seed germination and post-germination offspring vigour. Of 14 case studies (11 species in 10 genera and four families of flowering plants), germination percentage or rate (speed) increased in six and did not increase in eight, whereas post-germination offspring performance increased in 11 and did not increase in three. In six of the eight cases in which germination was not increased, seedling/juvenile vigour was increased. Seed mass was less likely to influence seed germination than seedling/juvenile vigour. Although selective abortion has been shown to increase progeny vigour of the early life history stages of plants, neither its demographic nor evolutionary importance has been demonstrated.