El tiempo de interferencia de arroz rojo sobre el rendimiento de las variedades Cimarrón y FONAIAP1

red rice (rr), an important weed in venezuelan rice farms, increases production costs because its presence is difficult to control with grass herbicides used in rice production. the objective of this research was to determine the effect of the duration of interference of brown awn red rice on yield and yield components of cimarrón and fonaiap 1 varieties. tow trials were established during the dry seasons of years 2000 and 2001 in municipio anzoátegui, cojedes state, venezuela. experimental design was a random block with a split plot arrangement and 3 repetitions, where main plots were cultivars and sub plots duration of interference (0, 15, 30, 45, 60 y 130 days after emergence, dae). cultivars were sowed at 130 plants m-2 and rr at 77 plants m-2. variables evaluated were: yield and its components (number de panicles m-2, grains per panicle, % sterility and weight of 1.000 grains). a variance analysis and duncan？s multiple range test for 5% were performed. results showed an overall negative effect of rr on yield and yield components. for cimarrón, reductions in yield multiple of 31 and 27 % were observed; in number panicle m-2 of 37 and 26%; and in number grains per panicle of 22 and 47%; for fonaiap 1 of 27 and 36%; of 39 and 55; and of 51 and 26% respectivily, during years 2000 and 2001. the total relative yield (try) of varieties was in the order of 0,36 and 0,41 for cimarrón and 0,46 and 0,37 for fonaiap 1, corresponding to years 2000 and 2001, respectively, indicating the establishment of an antagonistic relationship between cultivars and red rice.