Journal of Agricultural Studies ISSN 2166-0379 2020, Vol. 8, No. 1 http://jas.macrothink.org 287 Phytotoxic Activity of Guapira graciliflora (Nyctaginaceae) on Weeds Allana Silva Rodrigues Dept. of Biological Science, Regional University of Cariri, Brazil E-mail: allanarodrigues048@gmail.com José Weverton Almeida Bezerra (Corresponding author) Dept. of Botany, Federal University of Pernambuco, Av. Prof. Moraes Rego s/n, Cidade Universitária, Recife, PE 50.670-901, Brazil E-mail: weverton.almeida@urca.br Viviane Bezerra da Silva Dept. of Biological Science, Regional University of Cariri, Brazil E-mail: viviane123silvab@gmail.com Adrielle Rodrigues Costa Dept. of Biological Science, Regional University of Cariri, Brazil E-mail: adrielle.arc@hotmail.com Felicidade Caroline Rodrigues Dept. of Botany, Federal University of Pernambuco, Av. Prof. Moraes Rego s/n, Cidade Universitária, Recife, PE 50.670-901, Brazil E-mail: rodriguescaroline26@gmail.com Karina Vieiralves Linhares Dept. of Biological Science, Regional University of Cariri, Brazil E-mail: karina_linhares@yahoo.com