Weedy rice belongs to the same species as grown rice, and because it has similar morphophysiological characteristics, its control is difficult, bringing negative effects to the crop. Thus, the work aimed to evaluate the allelopathic potential of the main paddy rice cultivars sowing in Santa Catarina on weedy rice. In the laboratory, with treatments organized in a 4 x 5 factorial scheme, the aqueous extract of four paddy rice cultivars (SCSBRS Tio Taka, SCS 116 Satoru, SCS 121 CL and SCS 122 Miura) was evaluated in five concentrations (0, 25, 50, 75 and 100%). In a greenhouse, with treatments in a 4 x 2 factorial scheme, the straw allelopathy capacity of the same rice cultivars in two quantities (0.0 and 3.0 t ha-1) was evaluated to suppress germination and weedy rice initial growth. All experiments were carried out in a completely randomized design. In the first assay, the aqueous extract of the paddy rice cultivars used in the state of Santa Catarina did not have an allelopathic effect on weedy rice. In the second assay, it was found that the presence of rice straw reduced the density of weedy rice plants. However, the presence of straw on the soil favored the initial growth of the weed, significantly increasing the plant height, number of leaves per plant and shoot dry biomass.
Effect of Cropping Season on Yielding Ability of Indica Paddy Rice Cultivars Grown in Southwest Warm Region in Japan