Estimation of Optimum Field Plot Size and Shape in Paddy Yield Trial

This paper is to estimate the optimum plot size with the shape for field research experiments on paddy yield trial considering the effect of plot size on variability in yield of crop as well as studying the coefficients of variation of different plot sizes and shapes of plots. The maximum curvature technique and comparable variance methods were exercised to estimate optimum plot size and shape using yield data of the 12m x 24 m (288 basic units) recorded separately from each basic unit of 1m x 1 m. Soil productivity contour map described graphically the productivity level of the experimental site. The index of soil heterogeneity (b = 0.12) indicated a degree of low similarity among the experimental plots. The results from comparable variance method were inappropriate for the estimation of the optimum plot size, where as maximum curvature technique revealed significant results. Under this method, the curve of the coefficients of variation decreased rapidly up to 18 basic units with each unit increase in the plot size. Based on the maximum curvature method the optimum plot size for paddy yield trial was estimated to be 6m x 3 m with rectangle shape for Rice Research Institute, Kala Shah Kaku, Lahore. This estimated plot size is larger than the plot size of 3mx5m generally used for paddy yield in the study area. The study results indicated that the coefficients of variation (35.24, 23.80, 21.50, 19.49 and 17.86 percent) declines with an increase in the plot size(1m , 2m , 3m , 4m , 6m ) respectively and this decrease 2 2 2 2 2 is maximum with the square shape plot of size (6mx6m) basic units. As a result, square shape seems better for large plot sizes in the study area.