CHANGES IN THE METABOLISM OF SOYBEAN PLANTS SUBMITTED TO HERBICIDE APPLICATION IN DIFFERENT WEED MANAGEMENT SYSTEMS

Technologies that advocate the use of herbicide-resistant crops are alternatives to weed control, but they may cause oxidative stress and change secondary metabolism of plants. Therefore, this study aimed to evaluate changes in the secondary metabolism of soybean plants which contained Cultivance (R) (CV), sulfonylurea-tolerant soybean (STS) and Roundup Ready (R) (RR) technologies submitted to the application of the mixture of herbicides imazapyr and imazapic in "plant-apply" and "apply-plant" management systems. Two field experiments, in which soybean cultivars were submitted to increasing doses of the mixture of herbicides imazapyr and imazapic, were performed. Aerial parts of plants were collected 10 days after crop emergence and stored at -83oC, until quantification of variables. In general, the soybean cultivar BRS382CV exhibited lower contents of chlorophyll than cultivars CD249STS and NA5909RR. Besides, increasing doses of the mixture of herbicides imazapyr and imazapic decreased contents of chlorophyll in the cultivars. Stress caused by herbicides induced more generation of ROS and effective response of the antioxidant system through enzymes SOD, CAT and APX.