Early planting dates maximize winter annual field pennycress (Thlaspi arvense L.) yield and oil content

Pennycress (Thlaspi arvense L.), a common winter annual weed species in North America, has received attention in recent years as a potential oilseed feedstock for biofuel production but little is known about best practices for its production as a managed crop. Therefore, the objective of this study was to determine optimum sowing date to maximize pennycress yield, oil content, and crude protein. Four field experiments with 10 unique sowing and harvest dates over 3 crop years were conducted in Morris, MN, USA. Pennycress was no-till seeded from late August to late October at a rate of 6.7 kg ha−1. Seed yield averaged between 99 and 1109 kg ha−1 when sown in late October and early September, respectively, while oil content for the same sowing period averaged between 26.8 and 36.3%, respectively. Yield was not related to in-season environmental variables, such as cumulative precipitation, soil temperature at planting, or accumulated photohydrothermal time. However, oil content was maximized under greater precipitation (r2 = 0.86), warmer soil temperatures (r2 = 0.62) and greater photohydrothermal time when modeled at 2, 4, 6, 8, 25, 50 and 100 cm soil depths (between r2 = 0.53 to r2 = 0.85). Results indicate that environment conditions favoring a long maturation period increased oil accumulation in seeds. Conversely, a longer growth period reduced seed crude protein. Although pennycress protein is expected to have industrial uses, managing for yield and oil content is preferred. Therefore sowing pennycress in late August through September in the northern Corn Belt will maximize yields and oil content.