Germination and electrical conductivity tests on artificially aged seed lots of 2 wall-rocket species

The aim of this study was to determine whether the loss of germinability and vigour in wall-rocket seed lots was related to electrolyte leakage. Ten seed lots of 2 wall-rocket species (9 of Diplotaxis tenuifolia and one of D. erucoides (Brassicaceae)) were stored at 45 °C and 70% relative humidity and electrolyte leakage was measured using the conductivity test. Small differences in longevity were found among species or seed lots, suggesting that a similar relative longevity might be expected within the genus Diplotaxis after artificial ageing, and that it will be above the average of that found in other species of the same family at similar storage conditions. Electrolyte loss was strongly related to loss of seed viability. There was a negative linear relationship between conductivity and seed germination (R2 = 0.85), and a positive relationship with T50 (R2 = 0.77). Small differences were found among species or seed lots regarding the correlation between electrolyte leakage and seed germination and vigour. Our results indicate that the conductivity method is able to predict the viability of wall-rocket seeds stored at 45 °C and 70% RH, with the same regression equation of conductivity and germination (–33.97x + 135.59) being able to predict the viability of different seed lots and species. A conductivity level ranging from 1.4 to 2.2 mS g–1 DW would indicate that the potential of a Diplotaxis seed lot to germinate has decreased to 80%. The correlation between electrolyte leakage and seed germination provides a valuable means for early detection of seed viability in wall-rocket seeds.