The objective of this study was to evaluate the competitive ability of the rice cultivar BRS Pelota with biotypes resistant or susceptible to the herbicide Quinclorac. The experiment was conducted under greenhouse conditions in a completely randomized design with four replications, with the treatments arranged in a 2 x 6 factorial. The experimental units consisted of plastic pots containing 10 dm³ of soil, with pH and nutrient level being previously corrected. The treatments consisted of a competition between a rice plant, BRS Pelota cultivar, with populations (0, 1, 2, 3, 4 or 5 plants per pot) of the barnyardgrass biotypes resistant (ECH-13) or susceptible (ECH -12) to the herbicide Quinclorac. The evaluations were performed at 40 DAE,including shoot dry weight (MSPA), growth rate (TC), specific leaf area (SLA), leaf mass ratio (LWR), leaf area ratio (LAR) and leaf area index (LAI). The interference in the development of the BRS Pelota rice cultivar was proportionally higher with population increase of both barnyardgrass biotypes. The biotypes showed, in general, similar competitive ability.
Echinochloa spp.; Oryza sativa; interference; relative indices
