Climate Change Modulates Glyphosate Efficacy and Species-Specific Stress Responses in Key Weed and Crop Species

Zahra Bitarafan

Abstract

Increases in atmospheric CO₂ and global temperatures are altering crop–weed dynamics, with implications for herbicide efficacy and future weed management. To simulate anticipated Nordic future climates, we performed controlled herbicide dose–response experiments on one crop species, oilseed rape (Brassica napus, C₃), and two weed species, wild oat (Avena fatua, C₃) and barnyard grass (Echinochloa crus-galli, C₄), under ambient (ca. 400 ppm CO₂, 18/12 °C day/night) and elevated (ca. 800 ppm CO₂, 20.5/14.5 °C day/night) conditions. Glyphosate efficacy was quantified across a range of application rates, and plant responses were evaluated through biomass reduction and transcriptomic profiling. We found that effective dose thresholds (ED₅₀ and ED₉₀) for the grass species did not significantly shift under future conditions; however, B. napus exhibited enhanced growth reduction at lower glyphosate doses under elevated CO₂ and temperature, indicating species-specific alterations in herbicide sensitivity. Transcriptome analyses revealed species-specific response patterns to glyphosate treatments and environmental conditions, indicating that future climate scenarios may differentially modulate regulatory networks governing growth, stress tolerance, and herbicide responses. These findings highlight the need to consider climate–induced physiological and molecular changes when projecting weed control strategies and herbicide dose recommendations in northern agronomic systems. This work contributes to understanding how elevated CO₂ and warming may reshape efficacy of widely used herbicides and species interactions in future cropping environments.

Authors

1. Zahra Bitarafan (presenting) [1]
2. Melissa Hamner Mageroy [1]
3. Rafael de Andrade Moral [2]
4. Najmeh Salehan [3]
5. Kristian Schmidt Nielsen [3]
6. Christian Andreasen [1,3]

Affiliations

[1] Norwegian Institute of Bioeconomy Research (NIBIO), Division of Biotechnology and Plant Health, Ås, Norway
[2] Maynooth University, Department of Mathematics and Statistics, Maynooth, Ireland
[3] University of Copenhagen, Department of Plant and Environmental Sciences, Taastrup, Denmark

Email (presenting author): zahra.bitarafan@nibio.no

Keywords

Carbon dioxide levels; Climate change; Elevated CO2; Elevated temperatures; Herbicide efficacy; Plant stress tolerance

Funding

This work was a part of the project “Weeds vs. Crops: the winner of climate change” financed by the Norwegian Institute of Bioeconomy Research (NIBIO) base funds from the Research Council of Norway (Contract number 342631/L10).

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