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

Location: Natural Products Utilization Research

Title: Growth, morphological, metabolic, and photosynthetic responses of clones of eucalyptus to glyphosate

item CERVEIRA, WILSON - Sao Paulo State University (UNESP)
item SANTOS DA COSTA, YANNA - Sao Paulo State University (UNESP)
item CARBONARI, CAIO ANTONIO - Sao Paulo State University (UNESP)
item Vacant, Vacant
item AGUIAR ALVES, PEDRO LUIS - Sao Paulo State University (UNESP)
item BIANCO DE CARVALHO, LEONARDO - Sao Paulo State University (UNESP)

Submitted to: Forest Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2020
Publication Date: 5/17/2020
Citation: Cerveira, W.R., Santos Da Costa, Y.K., Carbonari, C., Duke, S.O., Aguiar Alves, P., Bianco De Carvalho, L. 2020. Growth, morphological, metabolic, and photosynthetic responses of clones of eucalyptus to glyphosate. Forest Ecology and Management.

Interpretive Summary: Drift of low levels of glyphosate spray drift to eucalyptus seedlings can cause unacceptable herbicidal damage. Seedlings from two different eucalyptus clones were tested for sensitivity to glyphosate. The GG100 clones plants were more tolerant to glyphosate than plants from the I144 clones. The difference in tolerance was related to differences in effects on photosynthesis parameters.

Technical Abstract: We hypothesized that eucalyptus has clone-dependent responses to glyphosate, and such differential responses might be associated with morphological, metabolic and/or photosynthetic changes. Experiments were carried out under controlled conditions of temperature, photoperiod and nutrition, focusing on evaluating the response of Eucalyptus x urograndis clones (GG100 and I144) to increasing doses of glyphosate (0 to 1,440 g ha-1 acid equivalent – AE) and to test whether a differential plant response would be associated to alterations in leaf morphology, plant and herbicide metabolism and photosynthesis. There was a significant reduction of plant height, stem diameter, number of leaves, leaf area and shoot dry mass caused by low doses of glyphosate (=180 g AE ha-1, while a strong plant growth reduction (~60%) was caused by glyphosate field doses (=720 g AE ha-1), in both clones. The GG100 clone was more susceptible to glyphosate field doses, while the I144 clone was more susceptible to glyphosate low doses. The stomatal index increased by 31% and the nervure thickness was reduced by 17% at 30 days after application of glyphosate at 180 g AE ha-1 (DAA) in the GG100 clone. Traces of glyphosate (<28 µg mg-1 of dry mass) were found in leaf tissues of both clones at 1 DAA. Shikimic acid accumulated earlier (after 1 DAA) and in greater amounts (90%) in the I144 clone. Aminomethylphosphonic acid (AMPA) was not detected in either treated clone. The CO2 assimilation rate, transpiration rate and stomatal conductance were reduced earlier (after 1 DAA) and more intensely (65%) in the I144 clone. The clone-dependent response is associated with changes in plant metabolism related to herbicide site of action and gas exchange.