Selectivity of herbicides in varieties of sugarcane

Abstract

Sugarcane varieties can present different responses to the herbicides and have as results phytotoxicity problems that could cause reduction in the sugarcane yield. With the objective of studying the selectivity of herbicides on the sugarcane varieties RB925345, RB925211, RB935744 and RB855036, four experiments were carried out in the random block design, one for each variety. The treatments consisted of herbicides trifloxysulfuron-sodium + ametryn (351 + 99 g a.i ha-1) + diuron + hexazinone (1097 + 27.77 g a.i ha-1), trifloxysulfuron-sodium + ametryn (1463 + 37 g a.i ha-1), diuron + hexazinone (1170 + 330 g a.i ha-1), metribuzin (4000 g a.i ha-1), imazapic (122.5 g a.i ha-1) and imazapyr (0.5 L a.i ha-1). Visual evaluations of selectivity were taken at 15, 30, 45, 60, 90 days after application (DAA), heights of the plants at 30, 90, 180 DAA, tiller height and technological analysis of soluble solids (oBrix), Pol (%) broth, Pol (%) cane, Fiber (%) and Purity (%) were made at 380 DAA. Initially all varieties presented intoxication symptoms due to herbicides. The inhibitors of ALS (imazapyr and imazapic) induced inhibition of growth, twisted leaves and purple coloration at 30 DAA. At 90 DAA the varieties did not present symptoms of phytotoxicity, being considered tolerant to the applied herbicides. Significant differences in tiller height, height of the plants, and technological quality were not observed due to treatments.