Fig. 4. Indirect responses of neutral detergent fiber (NDF) concentration to divergent selection for particle size reduction index (PSRI) in four smooth bromegrass populations. Means are over four replicates, three locations, 3 yr, and three harvests. Solid lines represent linear selection responses (b) and dashed lines represent effects of drift (d). R² = 0.09, 0.54, 0.61, and 0.32 for Alpha, WB19e, Lincoln, and WB88S, respectively.