Pantel, A., Romo, J. T. and Bai, Y. 2011. Above-ground net primary production of plains rough fescue [Festuca hallii(Vasey) Piper] after a single defoliation on five landform elements. Can. J. Plant Sci. 91: 689-696. Above-ground net primary production (ANPP) was determined for plains rough fescue [Festucahallii (Vasey) Piper] following a single defoliation to 7.5 cm stubble height on five landform elements in the Northern Mixed Prairie. The landform elements included north aspect-concave slopes, north aspect-convex slopes, south aspect-concave slopes, south aspect-convex slopes, and level uplands. Above-ground net primary production was determined for 2 yr after defoliating plants in May through November. Above-ground net primary production after defoliation was not dependent on landform elements in the first (P=0.23) and second years (P=0.22) after defoliation. In the first year after June through September defoliation, ANPP was reduced 29 to 41% (P <0.01), whereas May, October, or November defoliation had no significant effect on ANPP. Above-ground net primary production did not vary significantly (P=0.61) among months of defoliation in the second year after defoliation. Less ANPP in the first year after June through September defoliation indicates the need for ≥1 yr of deferred use to allow plants to regain their production potential. Unaffected ANPP after May, October, or November defoliation suggests plains rough fescue can be grazed annually. Recuperation of ANPP after defoliation depends on the month of the year in which plains rough fescue is defoliated, but not on landform elements in the Northern Mixed Prairie.