Journal of Agricultural Science; Vol. 10, No. 9; 2018 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education 423 Phytotoxicity of Herbicides in Seedlings of Sweet Passion Fruit Uirá do Amaral 1 , Luiz Leonardo Ferreira 2 , Kelly Martins de Souza 2 , Emerson Pereira Vieira 2 & Michelle Nunes Barcelos 3 1 Federal Institute of Education Science and Technology of Triângulo Mineiro, Minas Gerais, Brazil 2 University Center Miners, Mineiros, Goiás, Brazil 3 Federal University Uberlândia, Minas Gerais, Brazil Correspondence: Uirá do Amaral, Federal Institute of Education Science and Technology of Triângulo Mineiro, Minas Gerais, Brazil. Tel: 55-34-992-636-600. E-mail: uira@iftm.edu.br Received: May 30, 2018 Accepted: June 29, 2018 Online Published: August 15, 2018 doi:10.5539/jas.v10n9p423 URL: https://doi.org/10.5539/jas.v10n9p423 Abstract The culture of sweet passion fruit has been increasingly studied and exploited commercially in Brazil, with emphasis on the State of São Paulo. This is due to the high value achieved in the market of fresh fruit and be considered a food with functional properties beneficial to human health. However, the cultivation on a large scale finds some obstacles, as the control of weeds with the use of herbicides. In this sense, the objective of this work was to evaluate the phytotoxicity of seven herbicides with different mechanisms of action in seedlings of sweet passion fruit. Different variables were assessed: initial plant height (IPH) and final plant height (FPH); initial number of sheets (INS) and end number of sheets (ENS); intoxication of plants (INTO); fresh leaf mass (FLM) and dry leaf mass (DLM); fresh stem mass (FSM); dry steam mass (DSM); fresh root mass (FRM) and dry root mass (DRM) and total dry mass (TDM). Chlorimuron-ethyl (ALS inhibitor), glyphosate (EPSP synthase inhibitor), paraquat (photosystem I inhibitor) and atrazine (photosystem II inhibitor) have the higher effect on the variables analyzed, and they caused some kind of intoxication in the plants of sweet passion fruit. Conversely, haloxyfop-p-methyl (ACCase inhibitor) and fomesafen (protox inhibitor) showed a lesser effect on the sweet passion fruit plants. Keywords: Passifloraceae, herbicides, phytotoxicity, fruticulture 1. Introduction The passion fruit is an important culture in the scenario of Brazilian fruticulture and currently major source generating of foreign exchange for the Country. Its fruits have excellent buds features and dietary qualities (Freitas et al., 2011), being the largest part of the fruits produced in Brazil are coming species Passiflora edulis var. flavicarpa. On the other hand, the sweet passion fruit (Passiflora alata Curtis) is native specie to South America, especially at Brazil, whose cultivation has expanded depending on the price achieved in the market (Bernacci et al., 2003). The species P. edulis represents 95% of the area cultivated in the country, used both in the processing and consumption of fresh fruits, followed by sweet passion fruit P. alata for fresh fruits consumption (Faleiro et al., 2011). Weed control is one of the capital requirements to provide suitable growth and establishment of passion fruit. The interference caused by weeds in orchards of passion fruit is critical in the early months after planting, since in this stage plants are smaller. Improper weed management can lead to reduced productivity and quality of passion fruit, as weeds compete against the crop for nutrients and water (Sousa et al., 2002). Although the fruit of the sweet passion fruit has a great market potential, there are still several questions about plant nutrition, pest and disease control, post-harvest and weed management. Regarding the weed control by means of herbicides, there is still not product registration at the Ministry of Agriculture, Livestock and Supply (MAPA). In an attempt to investigate the phytotoxic effects of herbicides applied in post-transplanting of seedlings of yellow passion fruit. Paiva et al. (2015) observed that of the 21 herbicides tested, at least four have caused reductions in height gain. These authors also observed that only the herbicides oxadiazon, fenoxaprop-ethyl, tembotrione, chlorimuron-ethyl and not harm growth and isoxaflutole not intoxicated the seedlings, being the