Physiological dose-response of coffee (Coffea arabica L.) plants to glyphosate depends on growth stage.

Leonardo Bianco de Carvalho1*, Pedro Luis da Costa Aguiar Alves2, Silvano Bianco2, Rafael De Prado3

Glyphosate is the main herbicide used in coffee (Coffea arabica L.) plantations in Brazil. Problems with herbicide drift commonly occur in orchard fields due to non-adequate spraying conditions. A series of experiments was carried out aiming to evaluate physiological dose-response of C. arabica plants submitted to exposure to simulated glyphosate drift in two distinct plant growth stages. Glyphosate was applied at 0, 180, 360, and 720 g acid equivalent (AE) ha-1 directly on coffee plants with 10 and 45 d after transplanting (DAT). Glyphosate doses in a range of 180-360 g AE ha-1 increased photosynthesis, transpiration and stomatal conductance since 10 DAT-plants up to 14 d after application (DAA) while, in 45 DAT-plants, an increase was observed only up to 2 DAA, but this pattern was not persistent afterwards so that no difference in gas exchange was observed at 60 DAA in both plants. Macronutrient content was not affected by glyphosate application in both plants. Plant DM accumulation was not affected by glyphosate application at 10 DAT-plants, but an increase in plant growth was observed when glyphosate was applied in a range of 360-720 g AE ha-1 in 45 DAT-plants. Coffea arabica cv. Catuaí Vermelho IAC-144 responded differentially to glyphosate drift depending on plant growth stage, regarding on photosynthesis, transpiration, stomatal conductance, and plant growth, in spite of macronutrient nutrition was not affected.

Keywords: Coffea arabica, N-(phosphonomethyl)glycine, herbicide drift, photosynthesis, plant nutrition.
1Universidade do Estado de Santa Catarina, Centro de Ciências Agroveterinárias (CAV/UDESC), Departamento de Agronomia, Avenida Luiz de Camões, 2.090, 88520-000, Lages, Brasil. *Corresponding author (lbcarvalho@cav.udesc.br).
2Universidade Estadual Paulista, Faculdade de Ciências Agrárias e Veterinárias (FCAV/UNESP), Departamento de Biologia Aplicada à Agropecuária, Via de acesso Prof. Paulo Donato Castellane, s/n, 14884-900, Jaboticabal, Brasil.
3Universidad de Córdoba, Escuela Técnica Superior de Ingeniería Agronómica y de Montes (ETSIAM/UCO), Departamento de Química Agrícola y Edafología, Carretera Madrid-Cádiz km 396, 14071, Córdoba, Spain.