A COMPARISON BETWEEN SINGLE SEED DESCENT AND EARLY CROSS SELECTION IN WHEAT BREEDING .2. THE EVALUATIVE GENERATIONS

Two selection procedures in wheat breeding were compared on the basis of their ability to supply high yielding inbred lines. The first procedure consists of an early selection between crosses in the F3 generation, based on cross performance. In the second procedure selection is postponed until the F6, which is derived by single seed descent. The two procedures are evaluated in a two year test, using pseudo-lines of spring wheat. These pseudo-lines consist of mixtures of varieties and enable an estimation of the true genetic parameters. In this way the accuracy of the predictions can be examined. The first year of this comparison comprised the actual selection process and in the second year an F6 and F7 generation were mimicked, based on the selected lines of the F3 and F6 respectively, and evaluated in a large yield test. This paper gives the final results after the second year. From the first year it was found that the F3 cross predictions were very inaccurate, whereas selection in the SSD-F6 appeared to perform well. This resulted in a higher yielding set of lines evolving from the SSD-F6. Despite a pronounced genotype-year interaction this difference in yield level was also found between the F7 and the F6 lines, derived from the selected crosses in the F3. We conclude that the early selection procedure is not advantageous compared to the fast SSD procedure.