Morphological, Histological, and Glyphosate Residue Analysis of Helianthus annuus L. Plants Treated with Glyphosate

Abstract

Several recent studies have shown that glyphosate and its metabolite, aminomethylphosphonic acid (AMPA), resist rapid degradation and, therefore, can accumulate in plants. Continuing our previous research, we aimed to investigate the effect of indirectly spraying glyphosate on leaves and soil on non-target plants in the case of Helianthus annuus L. The plants were treated with glyphosate in their 5–6 leaf stages, the effects of which were assessed two weeks later from a morphological and histological point of view, as an evaluation of the residues of glyphosate and its metabolite, AMPA. They had an effect on both treated groups. In the case of the morphological parameters (plant height, number of leaves, and fresh and dried root and green mass), the data of the treated plants were statistically lower than in the case of the control group. The epidermis and the transport tissue system were damaged, and tissue death was observed in plants exposed to glyphosate. Both compounds were detected in all plant parts (roots, stems, lower leaves, and upper leaves), well above the limit of detection (0.025 mg/kg) and limit of quantitation 0.075 mg/kg showing a statistical difference with the control plants. This proved that glyphosate is incorporated into the plant organism even when applied indirectly.

An Analysis of Miscible Displacement and Numerical Modelling of Glyphosate Transport in Three Different Agricultural Soils

“…The leaching of glyphosate in sandy soils without macropores was also reported by other studies [14][15][16]. Structured soils [17] with macropores can enhance pesticide transport rates, and glyphosate (and AMPA) has been reported to leach from subsurface sites [10][11][12].…”

“…In soil materials, glyphosate shows extreme solubility, mostly because of the presence of aluminium oxides and iron oxides in the compound, along with a low pH value [3][4][5][6][7][8][9][10][11][12]. The amount of glyphosate in soil has been shown to vary according to pH, iron and aluminium oxides, and soil structures as well as the timing and activity of glyphosate application [3,8,[12][13][14][15][16].…”