ABSTRACT:
Herbicides are inputs with a high volume of use in agricultural production systems for weed management; however, the environmental contamination they cause is a reality. The objective of this research was to evaluate the tolerance of tree species used for the phytoremediation of herbicides in the soil, to atrazine, clomazone and 2,4-D, through the evaluation of photosynthetic indices. Thus, a randomized block design experiment was conducted with four replications, in a 4 x 5 factorial arrangement, where the first factor represented the herbicides atrazine, clomazone and 2,4-D and the control treatment without herbicide (water). The second factor consisted in the use of pre-selected tree species for the phytoremediation of soils with residues of the products [Eremanthus crotonoides DC. (candeia), - Richeria grandis Vahl (richeria), Protium heptaphyllum (Aubl) Marchand, (breu-branco) Kielmeyera latrophyton Saddi, Kew Bull, (pau-santo) Calophyllum brasiliense Cambess (guanandi)]. The herbicides were applied through dishes placed under the culture containers of the plants, when they presented eight months of development. After 15 days from the herbicide application, the visual intoxication, stomatal conductance (Gs), transpiration rate (E), CO2 concentration in the substomatal chamber (Ci), and water use efficiency (WUE) were evaluated. The herbicides affected differently the physiological characteristics of the tree species; atrazine was the most harmful product. Individuals under the effect of 2,4-D and clomazone presented lower variation for their physiological characteristics, compared to the respective control treatments. Breu-branco, despite showing low visual intoxication provided by the herbicides, was the most affected species by the products. On the other hand, candeia was the most tolerant species to the action of the herbicides.
Keywords:
photosynthesis; visual intoxication; atrazine; clomazone; 2,4-D