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

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.

Effect of glyphosate and P on the growth and nutrition of Coffea arabica cultivars and on weed control

“…This may be related to the fact that the subdoses of the herbicide were not enough to cause injury to the plants. Similar results were observed in the cultivars Catuaí/IAC-144, Acaiá/IAC 479-19 and Catucaí-Amarelo/2SL, that were also submitted to glyphosate subdoses (57.2, 115.2, 230.4 g ha −1 ) 26 , 28 .…”

Simulated Drift of Dicamba and Glyphosate on Coffee Crop

“…Ref. [13] observed severe damage to the coffee leaf blade with simulated glyphosate drift, reporting chlorosis and leaf blade narrowing. Furthermore, these studies underscored that glyphosate translocation occurs at a slower pace in plant tissues when exposed to lower doses.…”

“…The physical classification of the size and shape of the beans was performed following the methodology described in the Brazilian Legislation [35] using a sample of 100 g of processed coffee and a set of circular (18,17,16,15,14, and 13/64ths of an inch) and oblong sieves (13,12,11,10,9, and 8/64ths of an inch). Circular sieves retained flat beans, and oblong sieves separated the "moca" beans.…”

“…[12] observed the effects of reduced dicamba and 2,4-D doses in cucumber (Cucumis sativus L.) and melon (Cucumis melo L.), reporting residual product after harvesting the fruits and severe phytotoxicity-mediated changes in both cultures. Other researchers have also reported the deleterious effects of herbicides on coffee crops, such as glyphosate, 2,4-D, and others [13,14]. However, the phytotoxic effects of dicamba on coffee plants are still unelucidated.…”