Aiming to determine the minimum number of repetitions necessary to reach preestablished levels of precision, an experiment was carried out under field conditions. Corn crop was maintained in the presence or absence of weeds up to 0, 10, 20, 30, 40, 50, 60 and 120 days after emergence. The experiment was conducted from December, 1997 to May, 1998, corresponding to the summer crop, on the Experimental Farm "Marcelo Mesquita Serva" at the University of Marília - UNIMAR, Marília, São Paulo - Brazil. The precision of combined replicates, evaluated by the least significant difference, continuously increased with addition of new repetitions. However, small reductions small reductions were observed after six repetitions. Average values of medium square of the residue, coefficient of variation and F of the treatments were not influenced by increase in the number of replications.
experimental design; methodology; Zea mays
