Photosynthetic activity of coffee after application of glyphosate subdoses/Atividade fotossintetica do cafeeiro apos aplicacao de subdoses de glyphosate

• Published in: Acta scientiarum. Agronomy 2013-01, Vol.35 (1), p.109
• Main Authors: de Carvalho, Felipe Paolinelli, Franca, Andre Cabral, Lemos, Vinicius Teixeira, Ferreira, Evander Alves, dos Santos, Jose Barbosa, da Silva, Antonio Alberto
• Format: Article
• Language: Spanish
• ISSN: 1679-9275
• DOI: 10.4025/actasciagron.v35i1.15440

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 Acaia (MG-6851), Catucai Amarelo (2 SL) and Topazio (MG-1190), and three subdoses of glyphosate (0.0, 115.2 and 460.8 g [ha.sup.-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 Acaia cultivar was the most tolerant. These transitory effects may result in irreversible and prolonged damage to crop growth. Keywords: herbicide, EPSPs, Coffea arabica, photosynthetic rate, drift. Para o controle de plantas daninhas em lavouras cafeeiras, os produtores utilizam herbicidas nao-seletivos, como o glyphosate, empregado em aplicacoes dirigidas. Apesar de todos os cuidados com a aplicacao, sao constatados casos de intoxicacao em plantas, sendo de fundamental importancia o conhecimento dos efeitos sobre os processos fotossinteticos. Objetivou-se com este trabalho avaliar as caracteristicas associadas a atividade fotossintetica entre cultivares de cafeeiro submetidos a doses de glyphosate. O experimento foi conduzido em casa de vegetacao utilizando-se tres cultivares de cafeeiro (Coffea arabica): Acaia (MG-6851), Catucai Amarelo (2 SL) e Topazio (MG-1190) e, tres subdoses do glyphosate (0,0; 115,2 e 460,8 g [ha.sup.-1]), em esquema fatorial 3 x 3. Em funcao da aplicacao do herbicida observou-se reducao de carbono interno, razao carbono interno e do ambiente, consumo de carbono e taxa fotossintetica, aos 15 DAA na quarta folha. Na mesma folha aos 45 DAA, constatou-se menor consumo de carbono pelos cultivares. Na ul