Photosynthetic activity of coffee after application of glyphosate subdoses

Abstract

Farmers use non-selective herbicides, such as glyphosate, in directed applications to control weeds in coffee crops. Despite the precautions used during the application of herbicides, there are usually reports of poisoning in plantation areas. Moreover, it is fundamental to understand the effects of glyphosate on photosynthetic processes. The present study aimed to evaluate the characteristics associated with the photosynthetic activity in coffee cultivars subjected to doses of glyphosate. The experiment was conducted in a greenhouse using three varieties of coffee (Coffea arabica), including Acaiá (MG-6851), Catucaí Amarelo (2 SL) and Topázio (MG-1190), and three subdoses of glyphosate (0.0, 115.2 and 460.8 g ha -1 ) in a 3 x 3 factorial scheme. Herbicide application led to reduced internal carbon, ratio between internal and environmental carbon, carbon consumption and photosynthetic rate at 15 days after application (DAA) in the fourth leaf. In the same leaf at 45 DAA, the carbon consumption of the cultivars was even less. Despite low carbon concentrations, no difference in consumption and photosynthetic rate was observed in the last leaf. Glyphosate caused metabolic damage with transitory effects on the photosynthetic rate; the Acaiá cultivar was the most tolerant. These transitory effects may result in irreversible and prolonged damage to crop growth.Atividade fotossintética do cafeeiro após aplicação de subdoses de glyphosate RESUMO. Para o controle de plantas daninhas em lavouras cafeeiras, os produtores utilizam herbicidas não-seletivos, como o glyphosate, empregado em aplicações dirigidas. Apesar de todos os cuidados com a aplicação, são constatados casos de intoxicação em plantas, sendo de fundamental importância o conhecimento dos efeitos sobre os processos fotossintéticos. Objetivou-se com este trabalho avaliar as características associadas à atividade fotossintética entre cultivares de cafeeiro submetidos a doses de glyphosate. O experimento foi conduzido em casa de vegetação utilizando-se três cultivares de cafeeiro (Coffea arabica): Acaiá (MG-6851), Catucaí Amarelo (2 SL) e Topázio (MG-1190) e, três subdoses do glyphosate (0,0; 115,2 e 460,8 g ha -1 ), em esquema fatorial 3 x 3. Em função da aplicação do herbicida observou-se redução de carbono interno, razão carbono interno e do ambiente, consumo de carbono e taxa fotossintética, aos 15 DAA na quarta folha. Na mesma folha aos 45 DAA, constatou-se menor consumo de carbono pelos cultivares. Na última folha apesar de inferiores concentrações de carbono, não obteve-se diferença no consumo e taxa fotossintética. O glyphosate resulta em danos metabólicos com efeitos transitórios sobre a atividade fotossintética, sendo o cultivar Acaiá o mais tolerante. Este efeito transitório pode resultar em danos prolongados e irreversíveis no crescimento da cultura.Palavras-chave: herbicida, EPSPs, Coffea arabica, taxa fotossintética, deriva. 110Carvalho et al.

Mitigation of glyphosate side effects on non-target plants: use of different agrochemicals as protectants in common bean plants

“…Leaf area of coffee plants was also reduced (CARVALHO et al, 2013), and flag leaves of rice plants showed slow and stunted growth, emerging as a shortened organ (DAVIS et al, 2011). Taken together, these results indicate that reduction of leaf area is a fast and common effect caused by glyphosate.…”

“…The loss of biomass also can be related to increase of stomatal resistance, reduction of chlorophyll content and decrease of photosynthetic activity in leaves, which impairs the production of photosynthates (BRECKE;DUKE, 1980;TAIZ;ZEIGER, 2010;ZOBIOLE et al, 2010;CARVALHO et al, 2013). This herbicide also restricts nutrient absorption (CAKMAK et al, 2009), so there are a probability that mitigation of side effects can be due, even partially, to replacement of nutrients found in amino acid-based product, since some nutrients take part in stomatal aperture, chlorophyll molecules, and photosynthetic mechanisms (TAIZ;ZEIGER, 2010).…”

<b>Water use efficiency by coffee arabica after glyphosate application

“…Any change caused by abiotic stress can be demonstrated as stomatal sensitivity in many cultivars of C. arabica and C. robusta (DAMATTA; RAMALHO, 2006). Such conditions stimulate stomatal closure and increase stomatal resistance, such as mechanisms of defense against dehydration, thus the plant reduces the loss of water by transpiration (LARCHER, 2004).…”

MORPHOLOGICAL AND PHYSIOLOGICAL CHANGES ON Schizolobium parahyba VAR. Amazonicum (HUBER EX DUCKE) BARNEBY PLANTS INTOXICATED BY GLYPHOSATE

“…Carvalho et al (2013) observed a decrease on the photosynthesis rate of coffee 15 days after the application of 60.8 g . ha -1 of glyphosate.…”