Nature of dormancy in seeds of Sesamum latifolium (Gillet

Abstract

Sesamum latifolium is a progenitor of the cultivated Sesamum indicum. The plant has medicinal value, is used as forage, and is a potential donor of genes for crop improvement. The seeds of this species do not germinate readily when harvested and sown under standard conditions. Inability to germinate hampers the exploitation of this species in crop improvement programmes as well as viability assessments by genebank curators and seed stockists. Various dormancy release mechanisms were tested on the germination of seeds of Sesamum latifolium with a view to determining the nature of dormancy and the appropriate release mechanism in this species. Pre-stored and freshly harvested seeds were used. An imbibition experiment assessed the permeability of the seed coat to water. Optimum germination temperatures were determined using a two-way thermogradient plate. Effects of surgical exposure of the embryonic axis, nipping away from the embryonic axis, and gibberellic acid application were also tested. The studies revealed that the seeds of this species have non-deep physiological dormancy and require alternating temperatures together with surgical exposure of the embryonic axis, gibberellic acid, or dry after-ripening. The appropriate dormancy release procedure when testing for seed viability of this species through a germination test is recommended