Abstract

CASTILLO, Rosana  and  GUENNI, Orlando. Latencia en semillas de Stylosanthes hamata (Leguminosae) y su relación con la morfología de la cubierta seminal. Rev. biol. trop [online]. 2001, vol.49, n.1, pp.287-299. ISSN 0034-7744.

The seed of Stylosanthes hamata is characterized by it's a high level of dormancy, which is imposed by seed-coat impermeability to water entry (harseededness or hard-seed condition). The level of hardseededness between upper and lower articulations of seven diploid and five tetraploid accessions was studied under tropical conditions. Germination tests on naked seeds (relative humidity:  55-65%, constant temperature:  27-30º C, photoperiod:  12/12 hr) showed that hard-seed percentage was, in most cases, over 85% independent of ploidy level and seed position within the fruit. Histochemical analysis indicated that hardseededness in this species was associated with a completely sealed microphile and hilum. This feature was also associated to:  a) an epidermis consisting of a palisade-like layer of macrosclereids, b) a like-line at the outermost region of these cells and c) a high concentration of hydrophobic compounds located all across the seed-coat.

Keywords : Stylosanthes hamata; hard-seed; hardseededness; dormancy; morpho-anatomical features; germination; seed-coat.