Seletividade de herbicidas aplicados na cultura do centeio para o controle de plantas daninhas

Abstract

The rye culture has great importance for human and animal nutrition, however, interference caused by weeds is one of the factors that most contribute to losses in productivity and grain quality. Therefore, the objective of this study was to evaluate the selectivity of herbicides applied for the control of weed infestations in the BRS Progresso rye cultivar. The experiments were replicated and conducted in June 2021 and the other in June 2022, using randomized blocks with four repetitions. The treatments tested in both experiments were as follows: doses of terbutilazina (500, 1000, and 1500 g ha-1 ), haloxifop-p-methyl (270 g ha-1 ), fluazifop-p-butil (187.5 g ha-1 ), iodosulfuron (5 g ha-1 ), fluroxypyr+triclopyr (461.2+1335 g ha1 ), clodinafop-propargil (96 g ha-1 ), quizalofop-p-ethyl (100 g ha-1 ), pinoxaden (40 g ha-1 ), sethoxydim (230 g ha-1 ), clethodim (108 g ha-1 ), and carfentrazone-ethyl (120 g ha-1 ), along with two control treatments, one hand-weeded and another infested. The variables analyzed were phytotoxicity (%) at 7, 14, 21, and 28 days after treatment application, internal CO2 concentration (µmol mol-1 ), transpiration rate (mol H2O m-2 s -1 ), stomatal conductance (mol m1 s -1 ), photosynthetic rate (µmol m-2 s -1 ), water use efficiency (mol CO2 mol H2O -1 ), and carboxylation efficiency (mol CO2 m-2 s -1 ). The herbicides terbutilazina (500 g ha-1 ), iodosulfuron-methyl, clodinafop-propargil, pinoxaden, and carfentrazone-ethyl demonstrated the highest selectivity for the BRS Progresso rye cultivar. The herbicides that caused the greatest phytotoxicity to rye were haloxifop-p-methyl, fluazifop-p-butil, and quizalofop-pethyl. Therefore the use terbutilazina (1000 g ha-1 ) showed the best performance in relation to the physiological variables of the BRS Progresso rye cultivar. The application of terbutilazina (1500 g ha-1 ) and carfentrazone-ethyl resulted the highest grain yield for the rye cultivar BRS Progresso.