Abstract
The sorghum crop in Brazil has expanded substantially. Among the factors that interfere in sorghum yield is the interference imposed by the presence of weeds. The objective of this study was to assess the potential of different herbicide treatments applied in pre-emergence or post-emergence of sorghum in terms of selectivity and weed control. Two experiments were conducted, one for each application modality: experiment 1: pre-emergence; experiment 2: post-emergence. The experimental design was a randomized block design with four replications, in split plots. For experiment 1, the pre-emergence herbicides applied constituted the plots, and the different sorghum hybrids (50A10, 50A40, 50A50, 1G100, 1G233, SS318) constituted the subplots. For experiment 2, the post-emergence herbicides applied constituted the plots, and the different sorghum hybrids (50A10, 50A40, 50A50, 1G100, 1G233, SS318) constituted the subplots. Based on the results obtained, and on the discussion done, it is possible to conclude that herbicides and their respectively doses that had potential for use in sorghum crop in pre-emergence were: atrazine (1000 and 2000), mesotrione (100), tembotrione (75), atrazine + mesotrione (1000+100 and 2000+100) and atrazine + trifluralin (1000+1000 and 2000+1000). Meanwhile in post-emergence the best options were: atrazine (1000 and 2000), mesotrione (50 and 100), bentazon (720), fluroxypyr (100), mesotrione + atrazine (50+1000) and mesotrione + fluroxypyr (50+100). All of those treatments provided less than 25% of plant injury which means less potential to reduce the sorghum grain yield. Key words: phytotoxicity, weed control, Sorghum bicolor, selectivity.
Highlights
In Brazil, grain sorghum has expanded to some areas where farmers have the ability to grow two crops on the same field per year
The application of the different herbicide treatments did not affect the emergence of the sorghum plants at 3 days after emergence of the sorghum (DAE) (Table 1)
What was observed was a delayed emergence of some hybrids when subjected to the application of some of the herbicide treatments, such as, for example, hybrids 50A50 and SS318, subjected to application of acetochlor and nicosulfuron, respectively
Summary
In Brazil, grain sorghum has expanded to some areas where farmers have the ability to grow two crops on the same field per year. Sorghum is usually grown after soybean crop as a successional crop. In season 2013/2014, the area sown with sorghum exceeded 800,000 hectares, especially in the “Cerrado” area which accounted for more than 482,000 ha (Conab, 2015). Sorghum crop has a very well adaption in this region because its temperature and rainfall requirements. Among the factors that interfere in sorghum yield is the interference imposed by the presence of weeds in the crop.
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