Utilization of uniformity trials to estimate the optimum plot size and shape and the number of replications in wheat yield trials [electronic resource].

Includes references.

In the present work, two uniformity trials were carried out during the first and the second winter seasons of 2011/2012 and 2012/2013 in the Experimental farm Demo, Faculty of Agriculture, Fayoum University. The main objectives were to estimate the optimum plot size, plot shape and number of replicates for wheat yield traits using the variety Sakha 93 as plant material. The cultivated area of each field trial was divided into 12 strips; each of which consisted of 100 rows, 0.2 m width and 3.0 m long. Two statistical methods including soil variability index and maximum curvature were used to estimate the optimum plot size and shape using the yield data of 1200 basic units (each of 0.6 m2). The data were subjected to two procedures of statistical analysis to estimate the optimum plot size, when the cost of conducting the experiment is not taken into consideration and to evaluate the effect of changing the plot shape on the variability. The first statistical method was that of maximum curvature which is based on the exponential relationship between plot size and the coefficient of variability. The second method was that developed by smith's method (1938). Bartlett's test for homogeneity of variances, as outlined by Steel and Torrie (1980), was used ~ to study the effect of changing plot shape. The obtained results could be summarized as follows: Increasing the plot size decreased the variance per basic unit and the coefficient of variability. However, the reduction was not in proportion with the increase in plot size.

Summary in Arabic.

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