Abstract
The most obvious use of uniformity trial data is to provide information on the most suitable size and shape of plot. The results of this study show that researchers should take into account the plot variability in layout of field experiments. Based on the coefficients of variation the optimum plot sizes for maize trials were estimated to be 3.75m x 3.75m (14.06m2 ) with square shape for Agricultural Research Institute (ARI), Tarnab, Peshawar, Cereal Crops Research Institute (CCRI) Pirsabak, Nowshera and Maize and Millet Research Institute (MMRI)Yousafwala, Sahiwal .This estimated plot size is smaller than the plot size of 15m2 usually used for maize yield trials in the study area. Square plots are also advisable either when the experimenter does not know the fertility pattern of the experimental area or when border effects are large. Keywords: Field variation, plot size, maize
