| Most of Brazilian cotton is produced in regions where annual rainfall exceeds 1,500mm, hence plant growth regulators (PGR) may be washed from the leaves before being absorbed. The objective of this research was to evaluate mepiquat chloride and chlormequat chloride washing from cotton leaves by rains occurring at different moments post spraying. The experiment was conducted in a greenhouse. Both PGR were sprayed to cotton at pin-head square at 15g ha-1 a.i. with and without a silicon-based adjuvant, and simulated rains were applied at 0, 0.75, 1.5, 3.0, 6.0, 12.0 and 24 hours after spraying, plus a control without rainfall. Addition of silicon adjuvant increased PGR uptake. Rainfall occurring up to 24 hours after spraying resulted in some PGR loss from... |
