TOLERÂNCIA DE DUAS ESPÉCIES DE JATOBÁ (Hymenaea courbaril L. e Hymenaea stigonocarpa Mart. ex Hayne) AO GLIFOSATO

Abstract

The objective of this work was to evaluate the herbicide glyphosate effect on Hymenaea courbaril L. seedlings. A randomized block design was used and 5 repetitions were used with an experimental unit composed of one jatobá plant in 5L pot. Treatments were: 0 (control); 9.6; 240; 480; 960 g a.ha-1 of glyphosate. Evaluations were performed 24 hours and 60 days after application. Gas exchange, respiration, photosynthesis, visual, anatomical and histochemical evaluations were carried out, where leaves from the middle third were collected, in addition to the growth in relation to the two dates. Visual and anatomical evaluations did not change, regardless of dose and action time, whereas histochemical analysis show an accumulation of starch grains in the mesophyll, adaxial epidermis and abaxial epidermis, which become more accentuated with increased concentration. The analysis of growth and developments showed that the seedlings showed an increase in the stem diameter, a decrease in the leaves number and a quadratic behavior in relation to the increase in height. There was an increase in the photosynthetic rate, in the electron transport rate, in the effective quantum yield of photosystem II and in the effective quantum yield of photosystem II, 24 hours after the glyphosate application The second physiological evaluation, 60 days after application, showed that the photosynthetic rate has a tendency to fall and that the transpiratory rate showed a quadratic behavior. Such results show that the cuticle probably had a protective effect for the plant, and the little absorbed may have had a hormonal effect, favoring the plants. With these studies we can conclude that the species Hymenaea courbaril is able to survive after contact with the glyphosate herbicide, showing no visual and / or anatomical damage, showing positive increases in growth and physiological characteristics.