Leaf Morphoanatomy and Biochemical Variation on Coffee Cultivars Under Drift Simulation of Glyphosate

L.A.C Reis,N.A.V.D Pinto,A.C França,F.P Carvalho,D.M.T Francino,A.F Freitas

doi:10.1590/s0100-83582018360100149

L.A.C Reis, N.A.V.D Pinto + Show 4 more

Open Access

https://doi.org/10.1590/s0100-83582018360100149

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Abstract

ABSTRACT: The most widely used herbicide in coffee crop is glyphosate, it inhibits the biosynthesis of secondary metabolites, responsible for structures and substances of plant defense. This work aimed to evaluate the morphoanatomy, total phenols, flavonoids and caffeine in leaves of Arabica coffee submitted to different sub-doses of glyphosate. The treatments were combinations of three coffee cultivars (MGS Travessia, Oeiras MG 6851 and Catuaí IAC 144) and five sub-doses of glyphosate (0.0, 57.6, 115.2, 230.4 and 460.8 g a.e. ha-1). The total thickness of the leaf blade, thickness of adaxial and abaxial epidermis, palisade and spongy parenchyma, in addition to the total phenol, total flavonoids and caffeine were evaluated 30 days after spraying. Catuaí showed a reduction in the total leaf thickness, while the others cultivars had an increase. The thickness of adaxial and abaxial epidermis and palisade parenchyma was reduced, and the spongy parenchyma increased with increasing doses of glyphosate, regardless of the cultivars. There was an increase on the total phenols up to 115.2 g ha-1 glyphosate, and above this dose, the concentrations of phenols were reduced. The Travessia and Oeiras cultivars obtained a reduction of flavonoids up to 115.2 g ha-1; and above this dose, the concentration of flavonoids increased. The Catuaí cultivar showed an opposing behavior of the concentration of flavonoids. Oeiras and Catuaí showed a decrease of caffeine up to 115.2 g ha-1 and an increase at higher doses. Travessia showed an increase of caffeine in sub-doses above 115.2 g ha-1. The three cultivars showed a higher concentration of phenols in the palisade parenchyma after the application of glyphosate drift. Glyphosate reduces the thickness of the adaxial and abaxial epidermis and palisade parenchyma, and increases the thickness of spongy parenchyma. Doses of glyphosate above 230.4 g ha-1 result in the reduction of total phenols. The concentration of flavonoids and caffeine has varying effects with glyphosate application.

Highlights

IntroductionThe interference imposed by weeds is an ongoing issue for the management of the crop
On coffee culture, the interference imposed by weeds is an ongoing issue for the management of the crop
The intoxication symptom shown by the plants treated with glyphosate was the narrowing and chlorosis of recently expanded leaves from the seventh day after the application on (DAA), and these were the most evident effects on plants treated with doses above 230.4 g ha-1, regardless of the cultivar (Figure 1)

Summary

Introduction

The interference imposed by weeds is an ongoing issue for the management of the crop. The competition of these plants with coffee may create irreparable damages, mainly during the initial growth phase of the culture, when it has a lower competitive ability, and its growth and nutrition may be affected by weeds (Fialho et al, 2012). The low soil covering promoted by the Young plant favors enough light incidence for the germination, growth and reproduction of weeds (Silva et al, 2008), enabling a high occurrence and intensity of the competition. The control is necessary in order to minimize the negative effects on the growth and production of coffee. Glyphosate is among the most used herbicides for this purpose (Mesquita et al, 2012)

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