Can light intensity influence the tolerance of Synedrellopsis grisebachii to glyphosate?

• Published in: Weed biology and management Vol. 16; no. 1; pp. 3 - 15
• Main Authors: Santos, Juciléia I., Amaral, Carita L., Alves, Pedro Luis C.A., Gasparino, Eduardo C.
• Format: Journal Article
• Language: English
• Published: Blackwell Science Asia 01.03.2016; Blackwell Publishing Ltd
• Subjects: chemical control; developmental stage; leaf anatomy; light intensity; Synedrellopsis grisebachii
• ISSN: 1444-6162; 1445-6664
• DOI: 10.1111/wbm.12085

Plant susceptibility to herbicides is related to several factors, including the environmental conditions under which the plants develop. Two experiments were carried out using Synedrellopsis grisebachii plants in two different developmental stages (vegetative and reproductive), with the goal of studying plant susceptibility to the herbicide, glyphosate, and the dependence of this susceptibility on light intensity (full sunlight and 70% shading), correlated with leaf anatomy. The experimental design for both experiments was completely randomized, with a 2 × 7 factorial scheme, with two light intensities and seven different doses of glyphosate (0D, 1/4D, 1/2D, D, 2D, 4D and 6D, where D is the recommended dose of 1800 g ae ha⁻¹) as the factors and four replicates per treatment. The leaf anatomy was characterized with optical and scanning electron microscopy. The plants that were grown in full sunlight were more tolerant of glyphosate because of thickening of the adaxial epidermis, parenchyma and main vein structures, which required higher glyphosate doses for effective weed control. The plants that were in the reproductive stage were more tolerant of glyphosate, probably because of lower glyphosate absorption and translocation to the reproductive organs.