Abstract

Ipomoea species are troublesome weeds in crop systems through Brazil. Drought stress typically reduces glyphosate efficacy by reducing the foliar uptake of herbicides and their translocation. Using both glyphosate tolerant (GT) and sensitive (GS) plants from Ipomoea grandifolia, I. indivisa and I. purpurea species, this research aimed to (a) correlate amounts of epicuticular wax and tolerance to glyphosate in plants and (b) determine the effect of drought stress (DStress) on changes in the quantity and chemical composition of plant epicuticular waxes. The dose that causes 50% inhibition of growth (GR₅₀) of the biotypes varied between 62 and 1208 (I. grandifolia), 159 and 913 (I. indivisa), and 389 and 1925 g a.e. ha⁻¹ of glyphosate (I. purpurea). There was low inverse correlation (–0.46) between the amount of epicuticular wax and the sensitivity to glyphosate. GT biotypes of the species presented greater plastic capacities than GS biotypes for increasing the amount of epicuticular wax under DStress. The three Ipomoea species exhibited different chemical profiles of waxes supported by IR spectra, which allows for their differentiation. For I. grandifolia and I. purpurea, there was an increase in the polar components in the state without DStress, while for the species I. indivisa, no differences in infrared spectra were detected between the two water conditions.

摘要

番薯种是整个巴西作物系统中的棘手杂草。干旱胁迫通常通过减少除草剂的叶吸收及其易位性来提高草甘膦的功效。这项研究旨在利用大叶番薯，印度洋豆和紫草物种的耐草甘膦（GT）和敏感（GS）植物，该研究旨在（a）关联表皮蜡的量和植物对草甘膦的耐受性，并（b）确定胁迫（DStress）对植物表皮蜡数量和化学组成变化的影响。引起生物型生长抑制50％（GR ₅₀）的剂量在62和1208（大叶鸢尾），159和913（印度斑潜蝇）之间变化），以及389和1925 g ae ha ^-1的草甘膦（I. purpurea）。表皮蜡的量和对草甘膦的敏感性之间呈低负相关（-0.46）。该物种的GT生物型在DStress条件下增加表皮蜡的数量显示出比GS生物型更大的可塑性。这三种番薯属植物表现出不同的蜡化学特性，并由红外光谱支持，从而可以区分它们。为I. grandifolia和I.菊，有在状态而不DStress所述极性组分的增加，而对于物种I. indivisa，分别在两个水条件之间检测到红外光谱没有差异。