Estimation of Optimum Plot Size and Shape from a Uniformity Trial for Field Experiment with Sunflower (Helianthus annuus) Crop in Soil of Hisar

A study of uniformity trial for assessing the nature and magnitude of soil variability and to determine the optimum size and shape of plots was conducted on 66A507 Pioneer hybrid of Sunflower crop at Research Farm of CCS Haryana Agricultural University, Hisar, Haryana during the February 2014 to June 2014, on a field of size 35 m × 40 m which after eliminating border effects reduced to 32 m × 36 m. The total area (1152 m2) divided into 1152 basic units, each have size 1 m × 1 m and yield data of all the basic units was recorded separately for further investigations. The coefficient of variation of yield of individual harvested units was observed to be as high as 13.92 per cent indicating high degree of soil heterogeneity. The coefficient of variation decreased with increase in plot size in both the directions i.e. when plots were elongated in N-S direction or elongated in E-W direction and the decrease was near about same for both the directions but was more when plots were elongated in N-S direction (96.48 per cent decrease). The long-narrow plots elongated in N-S direction were found to be more useful than the compact and square plots. It was observed that the smallest plot has the maximum efficiency and the optimum plot size was estimated to be 2 m2.