Abstract
ABSTRACT Identifying the competitive ability of corn hybrids and the economic injury level (EIL) caused by Urochloa plantaginea is important for the adoption of integrated management of this weed. This work aims to evaluate the interference and EIL of U. plantaginea infesting corn hybrids. Treatments included the corn hybrids Syngenta Status VIP3, Syngenta SX8394 VIP3, Pioneer P1630H, Pioneer 30F53 YH, and Dow 135021, as well as 12 densities of U. plantaginea for each hybrid. We used a rectangular hyperbolic model to describe the relationship between corn grain productivity loss and the explanatory variables — plant density (PD), dry mass (DM) of the aerial parts, ground cover (GC), and leaf area (LA). EIL was determined using grain productivity, control cost, corn price, and herbicide efficacy. The rectangular hyperbolic model provides a satisfactory estimate of grain productivity loss regarding the interference of U. plantaginea in corn culture. The hybrids Pioneer 30F53 YH and Pioneer P1630H presented better competitiveness and higher EIL. Sowing the hybrids Pioneer P1630H, Pioneer 30F53 YH, and Dow 135021 increased EIL, justifying the adoption of control measures for U. plantaginea at higher densities.
Highlights
MATERIAL AND METHODSIn Brazil, corn is an important cereal since approximately 95 million tons of grains are produced in an area of about 17.7 million hectares (USDA, 2019)
In all corn hybrids tested, the rectangular hyperbolic model was adjusted properly to the data, showing average values of R2 for plant density (PD), ground cover (GC), leaf area (LA), and dry mass (DM) over 0.69 and a low QMR, which characterizes a good fit of the data to the model
The results show that the values estimated for the parameter i tended to be larger for the corn hybrid Syngenta SX8394 VIP3 when compared to the mean values of all variables evaluated — PD, LA, GC, and DM (Table 1)
Summary
In Brazil, corn is an important cereal since approximately 95 million tons of grains are produced in an area of about 17.7 million hectares (USDA, 2019). This level of production is only possible because of enhanced culture management, associated with the use of hybrids with high productive potential due to genetic improvement (BRITO et al, 2011; SILVA et al, 2011). Among the weeds that affect corn productivity, presenting a high competitive ability for environmental resources, Urochloa plantaginea stands out (VIDAL et al, 2004; GALON et al, 2008). It is necessary to understand the damage caused by the competition and its influence resulting from the change in density and/or the culture management strategy adopted (AGOSTINETTO et al, 2010; KHATOUNIAN et al, 2016)
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