The Effect of Field Blocking on Gain from Selection

Abstract

An important choice in the evaluation of genetic material is the environmental design for testing genetic entries. Three incomplete block designs are compared in this paper in terms of expected gain from selection, and the relationship between this criterion and the criteria of mean-square error and average error variance is pointed out. Use is made of an empirical index of soil heterogeneity to characterize the environmental variability. In general, the proper weighting of block information resulted in increased gain from selection over that obtained without blocking in all of the designs. The inclusion of check plots did not appear to be a desirable alternative. The effect of genotype by environment interactions on these results and some of the limitations of the methods used are discussed.