HIGHLIGHTS:

Doses of glyphosate below 240 g acid equivalent [a.e.] ha^-1 cannot suppress forage growth and yield.

Megathyrsus maximus cv. BRS Quênia without glyphosate application increases the number of bedridden plants of maize.

The presence of M. maximus cv. BRS Quênia in intercropping with maize exerts crop control on weeds.

ABSTRACT

In the intercropping of maize with Megathyrsus maximus, the application of herbicides is a technique that can be used to reduce competition between intercrops. This study aimed to evaluate the effect of different glyphosate doses on suppressing the growth of Megathyrsus maximus cv. BRS Quênia intercropped with maize, as well as in weed control. The randomized block experimental design was used and conducted in the field. The treatments consisted of the application of six glyphosate doses, 0; 48; 96; 240; 480; 960 g acid equivalent [a.e.] ha^-1, and a maize treatment without the forage with 960 g acid equivalent [a.e.] ha^-1. The dose of 260.87 g a.e. ha^-1 provides a 50% response to the forage production variable; therefore, it has the potential to suppress M. maximus cv. BRS Quênia. The presence of forage reduces the density and dry mass of weeds, with the species in the weed community: Ricinus communis, Eleusine indica, Alternanthera tenella, Commelina benghalensis, Conyza sp., and Digitaria horizontalis.

Key words:
Zea mays; Panicum maximum; glyphosate underdose; weed control; phytointoxication