Abstract
Many coffee growers apply glyphosate in directed applications, but some phytotoxicity has been noted. It is believed some herbicides can exert a direct or indirect negative effect on photosynthesis by reducing the metabolic rate in a way that can affect the water use efficiency. The objective of this study was to investigate the variables related to water use among coffee cultivars subjected to the application of glyphosate and the effects of each dose. The experiment was conducted in a greenhouse using three varieties of coffee ( Coffea arabica ), Acaia (MG-6851), Catucai Amarelo (2SL) and Topazio (MG-1190), and three doses of glyphosate (0.0, 115.2 and 460.8 g acid equivalent ha -1 ), in a factorial 3 x 3 design. At 15 days after application, a reduction in stomatal conductance was observed, and smaller transpiration rate and water use efficiency were found in the fourth leaf at 15 days after application. There was a decrease in the transpiration rate at 45 DAA, with the Acaia cultivar showing reductions with 115.2 g ha -1 . There was transitory reduction in water use efficiency with glyphosate application, but can affect the growth and production. The Acaia cultivar showed the highest tolerance to glyphosate because the water use efficiency after herbicide application.
Highlights
The occurrence of weeds in coffee plantations can result in competition for such resources as water, nutrients and light, requiring that decisions be made regarding control of the weeds
For economic and environmental reasons, the control method utilized by many coffee growers is the use of glyphosate in direct applications to guarantee crop selectivity
The measurements for the fourth leaf at 15 days after the application (DAA) of glyphosate demonstrated that there was a difference among the cultivars in relation to the means for the stomatal conductance and transpiration rate (E)
Summary
The occurrence of weeds in coffee plantations can result in competition for such resources as water, nutrients and light, requiring that decisions be made regarding control of the weeds. For economic and environmental reasons, the control method utilized by many coffee growers is the use of glyphosate in direct applications to guarantee crop selectivity. Due to the dispersion of the droplets to non-target plants, a phenomenon known as drift, intoxication in coffee. Agronomy plants was noted after the direct application of glyphosate to weeds (RODRIGUES et al, 2003). In addition to visual symptoms of intoxication, it has been reported that there may be damage to the growth and nutrient uptake of the coffee plants (FRANÇA et al, 2010a and b).
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