COMPARISON OF TANDEM AND INDEX SELECTION IN THE MODIFIED PEDIGREE METHOD OF BREEDING SELF-POLLINATED SPECIES

Abstract

Two-stage tandem selection and index selection were simulated for the modified pedigree method of breeding self-pollinated crops. We assumed that two traits were negatively correlated due to repulsion linkages, and considered correlations ranging from 0.00 to −0.95 corresponding to linkage intensities of 0.50 to 0.05. Each trait was controlled by five different loci with equal genetic effects. Three levels of environmental variability were assumed. Economic values were set at 0.5, 1.0 and 1.5 for one trait and 1.0 for the other.Index selection was superior to tandem selection for all combinations of parameters simulated. The efficiency of tandem selection was increased substantially by selecting the most valuable trait first. The efficiency of index selection can be increased by more frequent estimation of selection index coefficients.We did not consider positively correlated traits.