ALTERNATIVAS PARA O MANEJO DE PLANTAS DANINHAS NO SORGO GRANÍFERO NA REGIÃO DOS CERRADOS

Abstract

Graniferous sorghum is one of the important crops sown for the succession of soybeans in the production of grains and forages. However, the weed chemical control operations in post-crop emergence are restricted due to herbicide scarcity. In this sense, this study aimed to evaluate the sorghum tolerance to atrazine and tembotrione association herbicides, and to establish strategies for weed management in crops. The experiments were carried out in the 2016, 2017, and 2018 off-season, and were clustered into five experiments. The first experiment was carried out in Rio Verde municipality, Goiás State (GO), Brazil, in 2016, and it was used randomized block design, four replicates, and 10x4 factorial scheme. The factors consisted of ten sorghum hybrids (AG 1085, Buster, BRS 380, BRS 332, DKB 540, DKB 550, Enforcer, 1G100, 50A10, and 50A70) associated with four tembotrione doses (0, 60, 120, 180 g a.i. ha-1). The second experiment was carried out in 5x3 factorial scheme, consisting of five tembotrione doses (0, 60, 120, 180, and 240 g a.i. ha-1) associated with atrazine (1,000 g a.i. ha-1) and three sorghum hybrids (AG 1085, BRS 330, and Jade), using the same herbicide doses and eleven sorghum hybrids (BRS 330, BRS 380, DKB 540, DKB 590, Jade, MS 320, Ranchero, XB 6020, XB 6022, 80G20, and A 9904) in Montividiu and Santa Helena de Goiás municipalities, Goiás State (GO), Brazil. The third experiment was carried out in a randomized block design, 3x2+1 factorial scheme, corresponding to three vegetative stages of application (V3, V5, and V7), two tembotrione herbicide doses (90 and 180 g a.i. ha-1), and the control without herbicide, in Rio Verde and Montividiu (GO), for two consecutive years, 2017 and 2018 off-seasons. The fourth experiment was carried out in a randomized block design, 3x2+1+1 factorial scheme, three vegetative application stages (V3, V5, and V7), two tembotrione herbicide doses ( 90 and 180 g a.i. ha-1), an additional treatment with atrazine and the control treatment in Rio Verde and Montividiu (GO) in the 2018 off-season. The fifth experiment was carried out in a randomized block design, 2x3x2 factorial scheme, two graniferous sorghum hybrids (Buster and BRS 330), three row spacings associated with topdressing nitrogen fertilization (with and without nitrogen) in Rio Verde and Montividiu (GO). In the experiments, the toxicity levels, agronomic characteristics, yield components, and the crop grain yield were evaluated. Graniferous sorghum showed different tolerance responses to the association of the atrazine and tembotrione herbicides; and the sown hybrids, the dose used, the application stage, and the edaphoclimatic conditions of the cultivation regions should be analyzed. It is proposed to reduce spacings and the nitrogen fertilization in cover to favor interspecific weed competition in the Cerrado region, taking into account the hybrid characteristics and the sowing region.