influcnce of naphthalic anhydride and I-Aminobenzotriazole on maize resistance to herbicides-interferences with growth

ABSTRACT

A lachlor, metolachlor and particularly atrazine significantly decreased fresh and dry weights of maize shoots. The magnitude of reduction being greater during the first 5 days; a partial recovery was set in thereafter. Naphthalic anhydride [NA] relieved these effects while 1-aminobenzotriazole [ABT] showed cumulative reductions Meantime, the three herbicides under investigation increased abscisic acid [ABA] significantly. These increases seemed to be partially nullified by NA but being unaffected by ABT. On the other hand, all herbicides provoked significant decreases in indole acetic acid [IAA] content, the alachlor effect was relatively small. An immediate recovery in IAA content was induced by NA whilst ABT appeared to augment IAA inhibition. Meanwhile the activities of IAA- oxidase and peroxidase were significantly increased by herbicides. The enzyme activities did not after by NA longer but being further propagated by ABT. The recovery of IAA by NA was confirmed by lesser enzyme activities, may be due to the detoxification of these herbicides to non-toxic compounds. Moreover the increases in enzyme activities could explain the IAA reduction by herbicides, particularly when ABT was present, probably because of the retardation in herbicide breakdown and consequently increase the Phytotoxicity. The conflicting changes in ABA and IAA contents as well as in enzyme activities could explicate the differential growth responses to different treatments