Seed pelleting and storage effects on germination of Pennycress (Thlaspi arvense L.)

Pennycress (Thlaspi arvense L.) is an emerging bioenergy oilseed crop of interest to farmers in the Upper Midwestern United States. Improved lines with beneficial agronomic traits are being developed, including lines with reduced silicle shattering and altered seed coat characteristics, though planting and establishment is still challenging for this small-seeded crop. A controlled-environment experiment was conducted to assess the impact of seed treatment and pelleting on pennycress germination and seedling vigor of four pennycress lines (three black and one golden colored seed) following storage for 0, 1, 3, 9, and 12 months in warm or cold conditions (23 & DEG;C or 10 & DEG;C, respectively). Seeds were either treated with a gibberellin A4+7 (GA) soak (positive control), seed pelleting, or pelleting with GA added to the binder solution in addition to the untreated control (negative control). After each storage duration, seeds were germinated in darkness and counted daily for 7 days to obtain total germination. Vigor indices were calculated using changes in daily germination values. For black-seeded lines, GA treatment increased germination over the untreated by 5%-75% and pelleting alone increased germination by 4%-30%, but only until 3 months of storage. The GA treatment did not increase germination of the golden-seeded line, and pelleting decreased germination after 3 months of storage. The GA soak treatment was most effective at improving seed vigor indices compared with other treatments, while pelleting negatively affected vigor scores at 9 and 12 months of storage. Similar effects on germination from treatment were observed under both warm and cold storage conditions. Results indicate seed treatment can benefit germination and vigor within 3 months of storage for black-seeded lines but may negatively affect performance of golden-seeded lines, or all pennycress seed types after 9 months of storage.