Abstract
Herbicides are the most commonly used means of controlling weeds. Recently, there has been growing concern over the potential impacts of global climate change, specifically, increasing temperatures and elevated carbon dioxide (CO2) concentrations, on the sensitivity of weeds to herbicides. Here, glyphosate response of both Conyza canadensis and Chenopodium album was evaluated under different environmental conditions. Reduced glyphosate sensitivity was observed in both species in response to increased temperature, elevated CO2 level, and the combination of both factors. Increased temperature had greater effect on plant survival than elevated CO2 level. In combination, high temperature and elevated CO2 level resulted in loss of apical dominance and rapid necrosis in glyphosate-treated plants. To investigate the mechanistic basis of reduced glyphosate sensitivity, translocation was examined using 14C-glyphosate. In plants that were subjected to high temperatures and elevated CO2 level, glyphosate was more rapidly translocated out of the treated leaf to shoot meristems and roots than in plants grown under control conditions. These results suggest that altered glyphosate translocation and tissue-specific sequestration may be the basis of reduced plant sensitivity. Therefore, overreliance on glyphosate for weed control under changing climatic conditions may result in more weed control failures.
Highlights
Weeds cause significant crop yield and economic losses in agriculture
Large differences in plant survival between current and projected environmental conditions were recorded for populations CA1, CA3 (C. album) and CCS (C. canadensis) in which no plants survived glyphosate treatment under LT/ACO2 but 61.1%, 69.0% and 64.0% of the plants tested, respectively, survived under high temperature and elevated CO2 (HT/ECO2) conditions (Table 1)
Based on the phosphor imaging results described above, which indicate that the largest differences in 14C-glyphosate translocation between plants grown under different environmental conditions, occur at 12, 24 and 48 hours after treatment (HAT), we investigated the absorption and quantified the distribution of 14C-glyphosate in different plant parts of C. album and C. canadensis under different environmental conditions (LT/ACO2 and HT/ECO2) at these time points
Summary
Weeds cause significant crop yield and economic losses in agriculture. The evolution of herbicide resistance is reducing the overall efficacy of chemical weed management. Negative impacts of climate change on agricultural productivity has been widely recognized, mainly in the form of potential 6–13% decreases in crop yields[7,8]. Mounting evidence suggests that changing climate conditions may reduce the sensitivity of weeds to some herbicides[2,9,10]. Glyphosate is the most commonly used herbicide in the world[11] It has a unique mode of action inhibiting 5-enolypyruvylshikimate-3-phosphate synthase (EPSPS; E.C. 2.5.1.19), a key enzyme in the biosynthesis of aromatic amino acids. Reduced glyphosate efficacy is mainly correlated with www.nature.com/scientificreports/. Glyphosate injury was found to be correlated with chlorophyll content[20,21]
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