Fig. 8. The observed relationship between early leaf area index, L, and canopy nitrogen content, N, for winter wheat ‘Arminda’ (data of Groot and Verberne, 1991) (A), and for rice ‘IR72’ (data of Zhong, 1999) (B). The line is the fitted relationship to the observed values (points). Data points for rice come from experiments in 2 years (open symbols for 1997, closed symbols for 1998), and the different symbols refer to four levels of treatment (1997, row spacing; 1998, amount of nitrogen applied).