Seletividade de sais de glyphosate aplicados em diferentes horários em milho RR

Abstract

Currently there are several formulations of glyphosate present in the market, with emphasis on salts of isopropylamine, di-ammonium, potassium salt and ammonium salt, and it is necessary to investigate the efficiency of these different salts and the effects caused in the corn crop. The objective of this work was to evaluate the different formulations applied at different times of the day, on the morphophysiological characteristics of corn. For this, the different salts (isopropylamine, di-ammonium, potassium salt and ammonium salt) were applied in the commercial doses recommended by the manufacturers at different times of the day (9, 12, 15, 18) in the corn crop, when was with four fully expanded leaves (V4). The phytotoxicity evaluations were performed 7 and 14 days after application of the treatments. The other evaluated variables were measured 30 days after sowing of the crop, with 8 fully expanded leaves (V8), being: plant height, stem diameter, chlorophyll, internal carbon concentration, 6 photosynthetic rate, stomatal conductance, leaf transpiration, efficiency water use, carboxylation efficiency, leaf area and plant dry mass. In view of the obtained results, it is observed that the salts when applied at the recommended dose, at different times of the day, do not cause phytotoxicity to maize. The potassium salt presented better results in most of the variables evaluated, different from the isopropylamine salt where it was shown with low results in almost all evaluations.