Germination niche of a neotropical dry forest species: seed osmotic stress and recovery

Abstract

Erythrina velutina Willd is a native Fabaceae with wide occurrence, mainly in the Caatinga Domain with multiple uses. This study aimed to compare the vulnerability/tolerance of seeds of four accessions of E. velutina to osmotic stresses. Four replications were conducted with 25 seeds, germinated in osmotic solutions of NaCl or PEG up to -1.73 MPa. Seeds that did not germinate after 14 days were recovered in distilled water. Obtained data were fitted in Boltzmann curves and t50 and synchrony were evaluated. A probit analysis was performed, and hydrotime and halotime models were constructed. In distilled water, the germination curve was similar for all accessions. When the concentration of salt or PEG in the substrate increased, the accessions differentiated into two groups. Two accessions - Jutaí 2012 and Jutaí 2015 - maintained high germination up to -0.86 MPa NaCl, while Caboclo 2008 and Caiçara 2011 accessions presented a lower germination speed. The hydrotime and halotime analyses separated the germination response of accessions according to their physiological quality and tolerance to osmotic and saline conditions. Seeds viability was maintained at both stresses, since germination was reestablished at distilled water, thus constituting a crucial response for this species’ survival and conservation.