Wheat (Triticum aestivum L.) seedlings grown from seeds produced in ''organic'' (non-chemical) and ''conventional'' cropping systems are characterized by a) similar rates of root and shoot growth, b) equal sensitivity to phytotoxicity by the herbicide glyphosate, and c) equivalent basal activity of the enzyme glutathione S-transferase (both in the roots and in the shoots). In addition, treatment of these seedlings with glyphosate leads to significantly higher contents of this enzyme both in the shoots and in the roots. However, time-course and dose-response investigations indicate significant differences in the induction pattern of glutathione S-transferase: the response of ''conventional'' wheat seedlings takes place earlier and with higher efficiency, than that of the ''organic'' ones.