This study aimed to evaluate the deposition of drops using two nozzle types over Eichhornia crassipes leaves. The first trial was arranged in a factorial design 2x4x7, as follows: 2 nozzle types (TX12 and XR11002VS), 4 vertical angles (0º, 30º, 60º and 90º) and 7 horizontal angles (0º, 15º, 30º, 45º, 60º, 75º and 90º). The laminar leaf was set up parallel to the jet spraying movement direction at a vertical angle of 90º, and perpendicular to the soil plane at a horizontal angle of 90º. Solutions of dyes FD&C Blue no. 1 at 1,000 ppm and FD&C Yellow no. 5 at 3.500 ppm were used as spraying tracers for flat fan and cone nozzles, respectively. The second trial was set up as a factorial design 2x2x3, being 2 nozzle types (TX12 and XR11002VS), 2 spray solution conditions (with and without Aterbane BR at 0.5% v/v) and 4 horizontal angles (0º, 45º and 90º). The vertical angle of 90º was assigned as pattern to all the treatments. Solutions of dyes FD&C Blue no. 1 at 1,000 ppm and FD&C Yellow no. 5 at 3.500 ppm were used as spraying tracers with or without surfactant, respectively. The results obtained from the first trial showed that the spray solution deposits observed on the whole leaf and on the foliar adaxial face of the laminar leaves of water hyacinth decreased as the vertical angle became higher, regardless of the nozzle type used. The lowest spray solution deposits were always related to the vertical angle of 90º, regardless of the horizontal angle adopted. No spray solution deposit was detected on the abaxial face of water hyacinth leaf at the combinations of the factors studied. In the second trial the same spray solution deposit was observed to decrease the whole leaf and adaxial faces as the vertical angle increased. Both nozzle types provided null and void deposits on the abaxial face when the surfactant was not used. However, the surfactant addition to the spray solution provided significant increases on the abaxial face of water hyacinth leaves.
drop deposition; water hyacinth; foliar architecture; surfactant; spraying technology
