Glyphosate-induced impairment of plant growth and micronutrient status in glyphosate-resistant soybean (Glycine max L.)

Abstract

This investigation demonstrated potential detrimental side effects of glyphosate on plant growth and micronutrient (Mn, Zn) status of a glyphosate-resistant (GR) soybean variety (Glycine max cv. Valiosa), which were found to be highly dependent on the selected growth conditions. In hydroponic experiments with sufficient Mn supply [0.5 μM], the GR cv. Valiosa produced similar plant biomass, root length and number of lateral roots in the control treatment without glyphosate as compared to its non-GR parental line cv. Conquista. However, this was associated with 50% lower Mn shoot concentrations in cv. Conquista, suggesting a higher Mn demand of the transgenic cv. Valiosa under the selected growth conditions. Glyphosate application significantly inhibited root biomass production, root elongation, and lateral root formation of the GR line, associated with a 50% reduction of Mn shoot concentrations. Interestingly, no comparable effects were detectable at low Mn supply [0.1 μM]. This may indicate Mn-dependent differences in the intracellular transformation of glyphosate to the toxic metabolite aminomethylphosphonic acid (AMPA) in the two isolines. In soil culture experiments conducted on a calcareous loess sub-soil of a Luvisol (pH 7.6) and a highly weathered Arenosol (pH 4.5), shoot biomass production and Zn leaf concentrations of the GR-variety were affected by glyphosate applications on the Arenosol but not on the calcareous Loess sub-soil. Analysis of micronutrient levels in high and low molecular weight (LMW) fractions (80% ethanol extracts) of young leaves revealed no indications for internal immobilization of micronutrients (Mn, Zn, Fe) by excessive complexation with glyphosate in the LMW phase.

Aplicação foliar de manganês em soja transgênica tolerante ao glyphosate

“…Não houve efeito da aplicação do glyphosate sobre as concentrações de manganês no tecido foliar da soja (Tabela 1), corroborando com os dados apresentados em outros trabalhos (BOTT et al, 2008;CORREIA & DURIGAN, 2009 …”

Manejo convencional do solo e semeadura direta com diferentes intervalos de dessecação do milheto sobre o desenvolvimento inicial da soja

“…Estudando a concentração de micronutrientes nas folhas jovens em soja transgênica, Bott et al (2008) não encontraram diferenças significativas com a aplicação de glyphosate. Santos et al (2007b) também não constataram alterações no teor de Mn em folhas de soja transgênica coletadas no florescimento, quando submetida à aplicação de glyphosate.…”

Evaluación de la toxicidad del Roundup en la germinación de semillas de maíz (Zea mays)

“…Aunque se han realizado estudios sobre efectos tóxicos en plantas que puedan verse afectadas por los diferentes usos de este contaminante (Bott et al, 2008;Travlos & Chachalis, 2013), son pocas las investigaciones en Colombia sobre los verdaderos efectos tóxicos del glifosato sobre la germinación de semillas.…”