Effects of defoliation on aboveground biomass and seeyield and quality of pennycress (Thlaspi arvense L.)

Pennycress (Thlaspi arvense L.) is being domesticated as a new winter cash cover crop for biofuel and bioproducts. However, the response of pennycress to defoliation from insect pests or other stressors is poorly understood. To our knowledge, only a single study has been conducted thus far to evaluate the effects of artificial defoliation on pennycress, but it was performed using potted plants in an artificial environment. Thus, over 2 years, we conducted the first assessment under field conditions to evaluate the impacts of artificial defoliation on field-grown pennycress aboveground biomass and seed yield and quality. Treatments were combinations of defoliation levels (25%, 50%, and 100%) and timings (rosette, flowering and pod growth stages), and an undefoliated control. Our results demonstrated that pennycress defoliation at the rosette or flowering stages was par-ticularly detrimental, highlighting them as critical growth periods for pennycress. These findings enhance our understanding of pennycress’s response to defoliation and are the first steps to inform the development of management recommendations for this emerging crop.