Fig. 2. Relationship between leaf area per plant and the number of ligulated leaves of inbred lines cropped at two N levels (HN and LN) during two experimental years (Exp 1 and Exp 2). Different fitted curves represent significantly (P < 0.05) different responses of leaf area production: (A) between N levels (inbred LP611), (B) between N levels and experiments (inbred ZN6), with maximum plant leaf area of HN Exp 2 > HN Exp 1 = LN Exp 2 > LN Exp 1, and (C) between N levels and experiments (inbred LP521), with maximum plant leaf area of HN Exp 2 > HN Exp 1 > LN Exp 2 = LN Exp 1.