Respostas fisiológicas das plantas de citros ao glyphosate

Abstract

Currently, weed control for citrus is more costly, as it is a perennial crop where weeds coexist at the same time and space, thus reducing control options. Also, there are reports of the excessive and inappropriate use of glyphosate by Brazilian citrus growers, which the producers themselves justify due to the current low level of control. Moreover, there is much speculation about the biochemical and physiological consequences of the interaction between citrus and glyphosate, and the existing works are incipient and inconclusive. This study aimed to evaluate the glyphosate implications, elucidating from disturbances in the shikimic acid metabolic route to the identification of the main routes of intoxication between this herbicide and citrus plants. Glyphosate by different routes (leaf, soil, and weeds) was evaluated on two soil types and different doses of glyphosate in Pêra orange tree seedlings. The experimental design was randomized blocks in a triple factorial scheme (2 soil types x 3 glyphosate application sites x 4 doses), three replications, with repeated evaluations over time. As the main results, glyphosate on citrus plants had the worst results for crop development and plant physiology, such as shikimic acid accumulation. At the same time, the application directed at weeds produced the best results since, with the control of these, there was better development of citrus plants, and the application directed at the soil presented insignificant results, regardless of the type of soil. Thus, it is concluded that there are significant differences between the glyphosate application sites and the herbicide doses used.