Yield tradeoffs of early corn harvest to enhance pennycress establishment

Oilseed pennycress (Thlaspi arvense L.) establishment following grain corn (Zea mays L.) harvest in northern latitudes is challenging because of the short duration between corn harvest and soil freeze. The use of shorter season corn hybrids for a region may partly solve this challenge, but tradeoffs in reduced corn yield may be a concern. This study evaluated corn relative maturity (CRM) hybrids on pennycress establishment, seed and oil yields, and corn grain yield tradeoffs. The CRM hybrids ranged from 76- to 95-day for northern sites (Morris and Rosemount, MN), and from 95- to 113-day for the southern sites (Custar, OH, and Lexington, IL). The checks were full-season corn (113- and 95-day corn for the southern and the northern sites, respectively) harvested for silage. Pennycress plant density, green cover, and yield were generally greater when pennycress was seeded following silage corn due to early seeding and reduced corn stover. Pennycress seed yields ranged from 388 to 778, 641 to 834, 362 to 784, and 834 to 2038 kg ha⁻¹ at Custar, Lexington, Morris, and Rosemount, respectively. The results showed that growing 86- and 105-day grain corn in the northern and southern sites, respectively, facilitated timely pennycress establishment with little or no corn grain yield loss compared with full-season hybrids. Developing pennycress varieties better suited for emergence under high corn stover or employing stover management practices to increase autumn emergence is suggested. Additionally, an economic analysis of the entire cropping sequence (corn–pennycress–soybean) is needed.