Fig. 2 Relationship between (a) the total phenol amount in the aerial parts and the NNI and (b) the total phenol amount in the roots and the NNI and between (c) the total phenol conc. in the aerial parts and the NNI and (d) the total phenol conc. in the roots and the NNI. S1996 and S1997: Fields at the Sagnanème site in 1996 and 1997; M1996 and M1997: Fields at the Médina site in 1996 and 1997