Seed behaviour in Phoenix reclinata Jacquin, the wild date palm

Abstract

Despite the importance of the palm family,Arecaceae, little has been systematically documented about the seed behaviour of the many species. The post-harvest seed behaviour ofPhoenix reclinata, the highly utilized wild date palm species distributed along the eastern seaboard of Africa, is investigated in the present study. While both embryo and endosperm water concentration declined as the seeds ofPhoenix reclinatamatured, they remained relatively high: this is a characteristic of (but not confined to) non-orthodox seeds. The ultrastructure of embryo cells, and the finding that negligible water uptake was required for the initiation of germination, were in keeping with the possible non-orthodox nature of the seeds. A developmental study revealed that between the acquisition of full germinability and complete pre-shedding maturity, germination performance appeared to be constrained, suggesting the presence of an inhibitor. Pre-treatment by soaking, mechanical or acid scarification had no significant promotory effect on either rate or totality of germination of matureP. reclinataseeds, while use of water transiently at 100°C was highly deleterious. However, germination of partially dehydrated seeds was initiated sooner if they had been soaked or scarified. MatureP. reclinataseeds tolerated dehydration to a mean embryo water concentration of 0.40 g g–1(dry mass basis; dmb), but at 0.14 g g–1, both rate and totality of germination were adversely affected. However, viability of seeds dehydrated to the mean embryo water concentration 0.40 g g–1declined during storage for 16 weeks. It is concluded thatP. reclinataseeds are non-orthodox, and are best categorized as showing intermediate post-harvest behaviour.