Fig. 3. Course of the N nutrition index (NNI) (see Eq. [1]) with days after emergence (DAE) of (A and B) potato and (C and D) wheat in (A and C) 1997 and (B and D) 1998. Bars represent the LSD (P = 0.05) at each sampling date. Data values are average NNI values at the largest possible DAE that cultivars could be compared. Open symbols represent potato cultivar Junior and wheat cultivar Axona, and closed symbols represent potato cultivar Agria and wheat cultivar Baldus for N1 (circles), N2 (triangles), and N3 (squares). Y, year; N, nitrogen; C, cultivar; *, **, and ***, significant at the 0.05, 0.01, and 0.001 levels, respectively; NS, nonsignificant at the 0.1 level.
