Fluorescence of chlorophyll a in pineapple plants submitted to herbicide applications ανά Corrêa, Juliano Miari, Ferreira, Evander Alves, Pereira, Gustavo Antônio Mendes, Piratoba, Alba Rocio Aguilar, Santos, José Barbosa dos, Oliveira, Carlos Henrique de, Silva, Cícero Teixeira