Glyphosate-Based Herbicides Alter the Reproductive Morphology of Rosa acicularis (Prickly Rose).

Alexandra R Golt,Lisa J Wood

doi:10.3389/fpls.2021.698202

Alexandra R Golt, Lisa J Wood

Open Access

https://doi.org/10.3389/fpls.2021.698202

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Abstract

Glyphosate is a broad-spectrum herbicide that is widely used in many different commercial formulations. Glyphosate-based herbicides (GBH) are used in forestry operations to reduce populations of plants that compete with merchantable conifers. Past research has found that low-dose GBH applications caused male sterility in agriculturally relevant plants, sparking a need to determine the potential impacts of forestry-related GBH applications on understory plants. We investigated the effects of GBH on the reproductive morphology of Rosa acicularis, a highly prevalent understory shrub within British Columbia, Canada, growing on three operational forestry cutblocks treated with 1.782 kg a.i./ha of glyphosate, in the Omineca Region, and also in a controlled experiment. We analyzed floral and pollen morphology from treated plants and compared these with untreated plants in both scenarios. Pollen viability of treated plants was reduced by an average of 66%, and >30% of anthers were non-dehiscent compared to controls across our three field sites and experimental plants. We also found alterations in pollen and petal morphology in flowers from treated sites and glyphosate residues present in floral tissues 2 years after GBH applications. It is important to fully understand how long GBH-induced change will impact forest vegetation, to preserve natural forest biodiversity and reduce anthropogenic influences on boreal forest ecosystems.

Highlights

AND BACKGROUNDGlyphosate, or N-(phosphonomethyl) glycine (C3H8NO5P), is the active ingredient of many prevalent, broad-spectrum herbicides used to reduce populations of unwanted, competitive plant species in forestry, agricultural, industrial, and domestic applications (Blackburn and Boutin, 2003; Health Canada, 2017)
We investigated the effects of glyphosate-based herbicides (GBH) on the reproductive morphology of Rosa acicularis, a highly prevalent understory shrub within British Columbia, Canada, growing on three operational forestry cutblocks treated with 1.782 kg a.i./ha of glyphosate, in the Omineca Region, and in a controlled experiment
The majority of herbicides used in British Columbia (BC) within the past 30 years have been glyphosate-based herbicides (GBH)

Summary

Introduction

AND BACKGROUNDGlyphosate, or N-(phosphonomethyl) glycine (C3H8NO5P), is the active ingredient of many prevalent, broad-spectrum herbicides used to reduce populations of unwanted, competitive plant species in forestry, agricultural, industrial, and domestic applications (Blackburn and Boutin, 2003; Health Canada, 2017). A large proportion of GBH treatments occurring in BC are applied aerially (Govindarajulu, 2008; Wood, 2019). This application technique is usually prescribed in harvested forest cutblocks that have been planted with coniferous trees, such as lodgepole pine (Pinus contorta) and Engelmannwhite spruce (Picea glauca x engelmannii), but where deciduous trees have grown quickly. Aerial applications of GBH are used to remove this deciduous competition, but result in unintended (off-target) treatment of plants growing beneath and beside these deciduous trees; these plants often survive because they have only received a partial application. Glyphosate residues in plant tissues are reported to vary in persistence depending on species and plant tissue type (Feng and Thompson, 1990; Wood, 2019; Botten et al, 2021; Sesin et al, 2021)

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