Role of the Endocarp in ‘Manzanillo’ Olive Seed Germination

Abstract

The endocarp of ‘Manzanillo’ olive ( Olea europaea L.) seeds was subjected to several treatments in order to determine its effect on germination of the olive seed. The endocarp inhibited germination in stratified as well as unstratified olive seeds. Removing the endocarp resulted in high percentages of germination, but only when it was completely removed or when the radicle end was removed. The endocarp did not inhibit germination by preventing imbibition, since water uptake occurred in the seed through the untreated endocarp and through the clipped cotyledon end. The endocarp also did not contain water soluble inhibitors that prevent germination. Rather, the endocarp seemed to inhibit germination through mechanical resistance. High percentages of germination can occur only when the structure of the endocarp is altered, reducing its resistance to embryo expansion.