Effect of seed density in the germination of three species of Astrophytum (Cactaceae)

Abstract

Fruits were obtained from wild populations of Astrophytum capricorne, A. myriostigma and A. ornatum in Coahuila, Durango and Hidalgo, respectively, in order to evaluate the effect of grouping on seed germination, comparing treatments of 10 individual seeds and 10 grouped seeds. All three species showed higher germination for individual seeds. Germination speed was not related to seed density. These results are in contrast with “sibling rivalry” hypothesis in which competition between sister seeds can inhibit germination to avoid competition due to a high density of seedlings.