Weed Community Shift and Crop Tolerance in No-Tillage Rice under Sequential Application of Glyphosate and Cyhalofop-butyl plus Ethoxysulfuron

The reliance on chemical weed control in No-Tillage (NT) rice systems often leads to ecological changes in weed community composition and raises concerns regarding crop safety. This research aimed to evaluate the dynamics of weed community shift (SDR) and assess crop tolerance following the sequential application of glyphosate (pre-plant) and a mixture of cyhalofop-butyl + ethoxysulfuron (post-emergence). The experiment was conducted from May to October 2025 at the Experimental Farm of Universitas Padjadjaran, using a Split-Plot Design with three replications. The results indicated a significant weed composition shift from a community dominated by broadleaves (Limnocharis flava and Salvinia molesta) before application to a grass-dominated community (Echinochloa crus-galli and Leptochloa chinensis) at 3 weeks after application (WAA). Regarding crop tolerance, transient phytotoxicity symptoms in the form of leaf chlorosis were observed at 1 WAA, particularly in the highest dose treatment (1.75 L/ha). However, the rice plants demonstrated a rapid physiological recovery mechanism, with symptoms disappearing completely by 3 WAA. This recovery was confirmed by the vegetative growth response, where the number of vegetative tillers showed no significant inhibition compared to the manual weeding control during the active tillering phase. These findings suggest that sequential application of these herbicides effectively manages the weed spectrum shift and remains agronomically safe due to the crop's high resilience.