Sharing agricultural areas with genetically modified corn, conventional corn is subject to drift of glyphosate applied to adjacent areas, requiring evaluation of consequences from this intoxication. Thus, this work was developed in order to evaluate the sensitivity of two conventional corn hybrids to subdoses of glyphosate herbicide. Three similar experiments were conducted in a greenhouse, between November 2023 and May 2024. The first and second experiments assessed the Biomatrix BM3051 conventional hybrid corn; the third experiment evaluated the Semeali XB8018 hybrid corn. All experiments used five subdoses of the glyphosate herbicide, at a highest dose applied of 144 g ha−1. Plants were sprayed at a vegetative stage of three to four leaves. Qualitative (description of anatomical and morphological changes) and quantitative symptoms were evaluated using a visual scale of phytotoxicity and dry matter mass. Glyphosate doses equal to or greater than 36 g ha−1 led to significant intoxication of corn plants, possibly reducing dry matter. Biomatrix BM3051 had greater sensitivity to glyphosate intoxication compared with Semeali XB8018 corn. Most common phytotoxic symptoms observed included (in increasing order of intensity): slight reduction in size, yellowish streaks, wrinkling of the leaf blade, chlorosis or bleaching of young leaves, purplish leaf blade, curled leaves similar to drought damage, excessive formation of adventitious roots, necrosis of older leaves, generalized necrosis, tillering and meristematic damage. For the hybrid Semeali XB8018, glyphosate-induced hormetic effect occurred at doses below 36 g ha−1. Considering 1,440 g ha−1 of glyphosate as a maximum dose, the 36 g ha−1 subdose equals 2.5 %. Thus, the severe toxic symptoms observed in the field may result from improper applications rather than from glyphosate drift into adjacent areas.
