SAFENING EFFECTS OF 1,8-NAPHTHALIC ANHYDRIDE IN CORN PLANTS TREATED WITH BENSULFURON-METHYL AND IMAZAQUIN

Safening effects of 1, 8-naphthalic anhydride (NA) on corn (Zea mays L .) plants treated with bensulfuron-methyl [BEN; methyl-2[[[[{(4, thoxy -2-pyrimidinyl)amino}carbonyl]amino]sulfonyl] methyl]benzoic acid] or imazaquin [IMA; 2-{4, 5-dihydro-4-methyl-4-(1-methyl hyl)-5-oxo-1H-imi dazol-2-yl}-3-quinolinecarboxylic acid] were investigated. NA safened the plants treated with BEN or IMA with a safening index of 10.2 or 5. 1, respectively. Optimum application of NA was achieved by seed dressi ng at 0.2% (w/w) by seed weight. The safening effect of NA tended to b e increased with an earlier application of the herbicides. NA stimulat ed the activities of acetolactate synthase (ALS) and acetyl CoA carbox ylase (ACCase) by 32 and 216%, respectively. The herbicides had no inh ibitory effect on ACCase activity either from control or from NA-treat ed plants. However, the herbicides greatly inhibited ALS activity. The herbicidal inhibition of ALS was alleviated by NA treatment. The herb icides induced the accumulation of pyruvate in treated tissues, but no pyruvate accumulation occurred in NA-treated plants. Therefore, it ca n be concluded that NA protects plants from the herbicide injury at le ast partly through the enhancement of ALS and ACCase activities, and t he reduction of pyruvate accumulation.