Fluorescence of chlorophyll a in pineapple plants submitted to herbicide applications od 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