Effects of the seed coat and water content on the tolerance to heat shock among seeds of Plathymenia reticulata Benth. and Stryphnodendron adstringens (Mart.) Coville (Fabaceae)

ABSTRACT

Seed coat and water content may be direct determinants of seed tolerance to heat shocks, which may also be determined by the origin of the seeds. To check this, seeds of Plathymenia reticulata and Stryphnodendron adstringens were collected in the north of Minas Gerais State (representing a dry savanna) and in the northeast of Mato Grosso State (wet savanna) of the Cerrado biome and subjected to heat shocks of 110, 140 and 170 ºC for 2.5 minutes under three conditions; intact, scarified, and scarified and soaked. Soaked and scarified seeds of both species germinated more quickly. For both species, seeds from dry savanna showed lower initial water content and slower germination, but greater tolerance to heat shocks than seeds from wet savannas. No survival was detected among seeds of P. reticulata after treatment of 140 ºC, while seeds of S. adstringens from dry savannas tolerated treatment of 170 ºC, regardless of being scarified and imbibed or not. We conclude that seeds of P. reticulata have a lower tolerance to heat shock than seeds of S. adstringens, that imbibed seeds are less tolerant to heat shock than non-imbibed seeds and that seeds from dry savannas are more tolerant to heat shock than those from wet savannas

Keywords:
Cerrado; heat shock; savanna; scarification; water content