Glutathione half-cell reduction potential as a seed viability marker of the potential oilseed crop Vernonia galamensis

Seeds of Vernonia galamensis (Cass.) Less. contain a high proportion of vernolic acid that is highly desirable for industrial use and emphasises the potential of this species for commercialisation. For successful commercialisation, seed quality during storage must be maintained and regularly assessed, which can be rapidly achieved by using biochemical markers of seed viability. In V. galamensis , three potential viability markers electrolyte leakage (as a measure of membrane integrity) and the antioxidants tocopherol and glutathione were investigated in highly viable, aged and dead seeds at 6% and 12% moisture content (MC). Both electrolyte leakage and tocopherol were not correlated with seed viability whereas the glutathione half-cell reduction potential ( E GSSG/2GSH ) correlated strongly with viability loss during seed ageing at both MCs. However, an increase in E GSSG/2GSH associated with viability loss was delayed in the drier seeds (6% MC), highlighting that the performance of this seed viability marker could be decreased in seeds which lose viability in, or close to, the glassy state.