الفهرس 
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Abstract
the aim was to ascertion the influence of four herbicides metribuzin , butachlor, pretilachlor, and chlorimuron-ethyl on the induction of glutathione (gsh) and other thiol forms , activities of glutathione s-transferases (gsts) and other gsh- associated enzymes. the obtained results are summarized as follow: reductions in fresh and dry weights and in photosynthetic pigments. accumulations of ammonia- and soluble-n accompanied by diminutions in total-n and protein contents. accumulation of some new bands of protein concomitantly with disappearance of some others. gsh was greatly induced principally by butachlor followed by pretilachlor. the induction by chlorimuron-ethyl appeared temporal. reductions in fresh and dry weights and in photosynthetic pigments. accumulations of ammonia- and soluble-n accompanied by diminutions in total-n and protein contents. accumulation of some new bands of protein concomitantly with disappearance of some others. gsh was greatly induced principally by butachlor followed by pretilachlor. the induction by chlorimuron-ethyl appeared temporal. gssg contents were increased by metribuzin while the other herbicides resulted in, if any, decreases. herbicides increased in protein-bound, non-protein and total thiol. activities of glutamine synthetase (gs) and glutamate synthase (gogat) were inhibited by the varied herbicides particularly with metribuzin. differential inductions in gst isoforms. more induction of the tested gst isoenzymes were restricted to butachlor followed by pretilachlor and finally by metribuzin and chlorimuron-ethyl. great enhancements in activities of (g-gcs), (gss), (gspx) and (gsr) by the different herbicides. these results revealed that both species resisted the effects of butachlor rather than metribuzin with intermediary resistance to pretilachlor or chlorimuron-ethyl. metribuzin was more depressive to growth and also was the least inductive of detoxicants and gsh-associated enzymes, seemed the most phytotoxic to both species followed by pretilachlor. butachlor and chlorimuron-ethyl appeared the least phytotoxic due to the adaptive role of protein and also to enhanced inductions of both the detoxicants and the gsh-associated enzymes