The objectives of this work were to compare mathematical models and identify, among morphologic variables, the one better adjusted to rice grain yield losses by interference of EEA 406 cultivar, simulating red rice. Four experiments were carried out, one in the field and the others in a greenhouse. Rice cultivars BRS-38 Ligeirinho, IRGA 417, and BR-IRGA 409, were studied in the field in row widths of 15 and 25 cm, and populations (ten levels) of concurrent cultivar. In greenhouse, tests in monocultures were carried out in a replacement series model. Data analysis were accomplished with application of linear and non linear regression models. The best adjustment of rice grain yield losses data was attained using the model with two parameters. Leaf area and soil coverage estimated better grain yield loss than dry weight of the simulating cultivar. The models show that reduction of crop row width increases the competitive ability of rice cultivars in relation to the concurrent genotypes.
Oryza sativa; rice cultivars; row width
