Abstract

We aimed with this work to evaluate the efficiency of the herbicide [imazapic + imazapyr] in the weed control, especially of the jointvetch, and its reflex in rice plant establishment and grain yield. A field study was conducted, where treatments were: control without herbicide application; Kifix^® 140g ha^-1 (24.5 g_a.i. ha^-1 imazapic + 73.5 g_a.i. ha^-1 imazapyr) and Kifix^® 280 g ha^-1 (49 g_a.i. ha^-1 imazapic + 147 g_a.i. ha^-1 imazapyr). We evaluated crop emergence up to 25 days after sowing, crop plant height 12 days after emergence (DAE), jointvetch plant density 31 and 62 DAE, jointvetch dry mass 62 DAE and general weed infestation 62 DAE. At the end of the crop cycle we evaluated grains per panicle, panicle and 1000 grain weight, panicle density and crop grain yield. There is a risk of 15% reduction in the establishment of Clearfield^® rice plants when the maximum dose of the herbicide [imazapic + imazapyr] is applied pre-emergence, but under appropriate conditions, the crop development tends to compensate for this reduction in establishment. The herbicide [imazapic + imazapyr] is effective on jointvetch, but under high infestation conditions, as in the present study, a complementary herbicide application is required to achieve adequate control of jointvetch and avoid rice grain yield reduction due to competition.

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