Glyphosate negatively affects pollen viability but not pollination and seed set in glyphosate-resistant corn

Abstract

Experiments were conducted in the North Carolina State University Phytotron greenhouse and field locations in Clayton, Rocky Mount, and Lewiston-Woodville, NC, in 2002 to determine the effect of glyphosate on pollen viability and seed set in glyphosate-resistant (GR) corn. Varieties representing both currently commercial GR corn events, GA21 and NK603, were used in phytotron and field studies. All glyphosate treatments were applied at 1.12 kg ai ha−1 at various growth stages. Regardless of hybrid, pollen viability was reduced in phytotron and field studies with glyphosate treatments applied at the V6 stage or later. Scanning electron microscopy of pollen from affected treatments showed distinct morphological alterations correlating with reduced pollen viability as determined by Alexander stain. Transmission electron microscopy showed pollen anatomy alterations including large vacuoles and lower starch accumulation with these same glyphosate treatments. Although pollen viability and pollen production were reduced in glyphosate treatments after V6, no effect on kernel set or yield was found among any of the reciprocal crosses in the phytotron or field studies. There were also no yield differences among any of the hand self-pollinated (nontreated male × nontreated female, etc.) crosses. Using enzyme-linked immunosorbent assay to examine CP4-5-enolpyruvlshikimate-3-phosphate synthase expression in DKC 64-10RR (NK603) at anthesis, we found the highest expression in pollen with progressively less in brace roots, ear leaf, anthers, roots, ovaries, silks, stem, flag leaf, and husk.

Biomonitoring of Genotoxic Effect of Glyphosate and Pendimethalin in <i>Vigna mungo</i> Populations

“…Similar observations have been reported by Jabee et al (2008) and Kaymak and Gokalp (2005) in Allium cepa, Pline et al (2003) in cotton, and by Thomas et al (2004) in corn. Variation in size of pollen was also observed.…”

O milho RR2 e o glyphosate: Uma revisão

“…Segundo Thomas et al (2004), a aplicação de glyphosate em milho RR2, em estádios superiores ao estádio V6, pode afetar a reprodução individual de plantas, pois afeta a quantidade e a qualidade de pólen produzido, assim como está relacionada a alterações no tamanho dos vacúolos. Este efeito, porém, não foi suficiente neste estudo para prejudicar a polinização e consequentemente a produtividade da cultura.…”

Physiological Effects of Late Season Glyphosate Applications on Peanut (Arachis hypogaea) Seed Development and Germination

“…Glyphosate applied to glyphosate resistant corn after the V6 stage of growth reduced pollen viability, although did not affect corn yield, which was attributed to the cross pollination ability of this crop (Thomas et al, 2004). Glyphosate applied during the reproductive stage of plant development is translocated and accumulated in metabolic sinks, such as reproductive tissues (Pline-Srnic, 2005).…”