Rice plant stands were counted at 14 DAS from four randomlyplaced row lengths of 1 m in each plot. The efficacy of herbicideswas evaluated at 26–27 DAS (before the spray of post-emergenceherbicides at 28 DAS) and at 42 DAS (14 days after the spray ofpost-emergence herbicides). At each sampling time, two quadratsof 40 cm × 40 cm were placed in each plot to determine the densityand biomass of weeds. At crop harvest, only weed biomass wasdetermined as weed density was difficult to evaluate. The biomasswas measured after drying the samples at 70 ◦C for 72 h. At harvest,rice panicle numbers were counted from four randomly placed rowlengths of 1 m in each plot. Grains per panicle were determinedby randomly sampling 20 panicles per plot. Rice grain yield wasdetermined from the harvested area (12 m2 in WS11 and 6 m2 inDS12). Grain yield was converted to t ha−1 at 14% moisture content.