Hormone type, soaking duration and seed coating affect dormancy and germination of pennycress (Thlaspi arvense) lines

Establishment of pennycress is key to ensure uniform stands and maximise canopy closure in autumn. Past work has demonstrated that selected seed treatments could improve germination and establishment, but the optimisation of these processes to minimise inputs and time have not been assessed. The objective of this work was to evaluate seed enhancement technologies (hormone application by soaking and seed coating) to overcome seed dormancy and/or enhance germination. Two black-seeded lines (‘MN106NS’ and ‘ARV1’) and one golden-seeded line (‘tt8-t/ARV1’) were examined. Seeds were soaked in gibberellic acid (GA4+7) or benzyladenine (6-BA), or distilled water for different durations (30, 60, 240 minutes) and compared to an unsoaked control. Results showed that the GA treatment significantly increased germination, particularly for ‘ARV1’ and ‘MN106NS’ lines. Seed coating increased seed diameter but did not enhance germination; instead, it hindered ‘tt8-t/ARV1’ germination by 99-100%. The study suggests soaking seeds for at least 30 minutes in a GA solution to improve germination in black-seeded lines, however, economic and logistical factors must be considered. None of the tested enhancements proved beneficial on the two seed lots of golden-seeded line ‘tt8-t/ARV1’ and further research is needed to examine more seed lots before conclusions can be made.