Abstract
The use of herbicides is a usual practice in E. camaldulensis nurseries and plantations. The most widely used herbicide is glyphosate, whose drift damages this plant leaves. Although the mechanism of action of glyphosate is well known, it is not clear which alterations lead to the death of plants. The aim of this work was to assess the physiological and anatomical responses of leaves of E. camaldulensis seedlings to glyphosate application. Tests were performed on one-year-old seedlings sprayed with 0, 65 and 130 g a.e. ha-1 glyphosate. Ten days after the application, we measured gas exchange and fluorescence emission of chlorophyll a. We also quantify the concentrations of chlorophyll a, shikimate, carbohydrates, K+ and Mg2+, and the anatomical parameters of epidermis and mesophyll. Data was contrasted using Fisher’s test (p<0.05). We concluded that glyphosate alters the physiology of E. camaldulensis, inhibiting photosynthesis, changing the metabolism of carbohydrates and the ionic homeostasis. Tissue disorganization, heavily marked at the level of mesophyll, indicates definite alterations.
Highlights
Weed management is one of the most relevant forestry practices in eucalyptus nurseries and plantations
The 65 g a.e. ha-1 and 130 g a.e. ha-1 doses decreased in 33 % and 71 % the net photosynthesis when compared with the control, respectively
The decrease in the net photosynthesis was partly caused by the stomatal closure because both gas exchange variables had the same response to the glyphosate application
Summary
Weed management is one of the most relevant forestry practices in eucalyptus nurseries and plantations. It is performed with mechanical or chemical methods, or the combination of both (Cerveira Junior et al 2020). The recurrent use of herbicides in forest plantation management can be harmful for the crop itself (De Carvalho et al 2018). Glyphosate (N-phosphonomethyl glycine) is among the most widely used herbicides (Gomes et al 2019) because it controls a broad spectrum of weeds.
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