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Research Project: New Weed Management Tools from Natural Product-Based Discoveries

Location: Natural Products Utilization Research

Title: Low doses of glyphosate enhance growth, CO2 assimilation, stomatal conductance and transpiration in sugarcane and eucalyptus

Author
item Nascentes, Renan - Sao Paulo State University (UNESP)
item Carbonari, Caio - Sao Paulo State University (UNESP)
item Simoes, Plinio - Sao Paulo State University (UNESP)
item Brunelli, Marcela - Sao Paulo State University (UNESP)
item Velini, Edivaldo - Sao Paulo State University (UNESP)
item Duke, Stephen

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2017
Publication Date: 5/9/2017
Publication URL: http://handle.nal.usda.gov/10113/5801815
Citation: Nascentes, R.F., Carbonari, C., Simoes, P.S., Brunelli, M.C., Velini, E.D., Duke, S.O. 2017. Low doses of glyphosate enhance growth, CO2 assimilation, stomatal conductance and transpiration in sugarcane and eucalyptus. Pest Management Science. doi:10.1002/ps.4606.
DOI: https://doi.org/10.1002/ps.4606

Interpretive Summary: Sublethal doses of herbicides can enhance plant growth and stimulate other processes, an effect known as hormesis. The magnitude of hormesis is dependent on the plant species, the herbicide and its dose, plant development stage, and environmental parameters. Glyphosate hormesis is well established, but relatively little is known of the mechanism of this phenomenon. The objective of this study was to determine if low doses of glyphosate that cause growth stimulation in sugarcane and eucalyptus concomitantly stimulate CO2 assimilation. Glyphosate applied at low doses increased the dry weight of sugarcane and eucalyptus plants in all experiments. Concomitantly, CO2 assimilation, stomatal conductance, and transpiration were increased by glyphosate doses similar to those that caused growth increases, indicating that low glyphosate doses enhance photosynthesis of plants.

Technical Abstract: Sublethal doses of herbicides can enhance plant growth and stimulate other process, an effect known as hormesis. The magnitude of hormesis is dependent on the plant species, the herbicide and its dose, plant development stage, and environmental parameters. Glyphosate hormesis is well established, but relatively little is known of the mechanism of this phenomenon. The objective of this study was to determine if low doses of glyphosate that cause growth stimulation in sugarcane and eucalyptus concomitantly stimulate CO2 assimilation. Shoot dry weight in both species increased at both 40 and 60 days after application of 6.2 to 20.2 g a.e. ha-1 glyphosate. The level of enhanced shoot dry weight was 11 to 37%, depending on the time after treatment and the species. Concomitantly, CO2 assimilation, stomatal conductance, and transpiration were increased by glyphosate doses similar to those that caused growth increases. Glyphosate applied at low doses increased the dry weight of sugarcane and eucalyptus plants in all experiments. This hormetic effect was related to low dose effects on CO2 assimilation rate, stomatal conductance and transpiration rate, indicating that low glyphosate doses enhance photosynthesis of plants.