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.