Abstract

The purpose of this experiment was to relate the tolerance of Commelina benghalensis to two different kinds of glyphosate formulation, in function of the absorption time and translocation of this molecule in the cells of this plant. The experiment was conducted in a greenhouse. The experimental design is a completely randomized design (CRD), with four treatments follows; glyphosate potassium salt and isopropylamine tested with commercial dosage, haematoxylin dye and a control, with three repetitions. Sample from the leaves, stems and roots were collected and subdivided in twenty-five subsamples. The evaluations were performed by microscopic views every 30 min, until the herbicide was absorbed into the parenchyma of the mesophyll. After 30 min of the application of isopropylamine glyphosate, there was accumulation of this molecule inside leaf apoplast which indicated the process of penetration of isopropylamine glyphosate. For the glyphosate potassium salt the absorption was observed 2 h after application. After 7 h, the presence of a small concentration of the product in the stem was verified. 12 h later, a low concentration was verified in the root. After 36 h the phloem was full of the isopropyl amine salt glyphosate, 86 h later its presence in the xylem and phloem, together with the symptoms of destruction of the parenchyma tissue was visualized. The solution with isopropyl amine salt, after 7 h, was seen in the phloem, with a 12 h concentration of isopropyl amine salt decrease in the stem, which overloaded the phloem of the root. After 86 h, all the parenchyma tissue of the xylem and phloem were destructed. The absorption and translocation of glyphosate depended on its formulation, which represented more or less tolerance of the plant to the herbicide, but tolerance was not the only factor influenced by anatomy, the physiological, biochemical and genetic features were also critical.

Key words: Phloem, morphology, tropical spiderwort.