Three cycles of recurrent selection in four Spanish landraces of maize

Abstract

Abstract Landraces of maize have a variability not found in the elite hybrids due to the bottleneck during selection. There is a renewed interest for using that variability, incorporating alleles for specific traits or widen the general variability of elite germplasm. In Europe, there is also an interest in the direct use of local landraces by farmer’s associations seeking for an agriculture that preserves crops diversity. Prebreeding programs are aimed to reduce the yield gap among landraces and improved materials. This paper shows the initial results of a prebreeding program consisting of three cycles of S₁ recurrent selection for grain yield in four local landraces from Northwestern Spain. All the populations had consistent yield gain in the first cycle of selection. However, the response in later cycles was different among the populations: one population had a continuous increase of 21% per cycle while two had reduced yield in the last cycles. Our results highlight the need to include secondary traits to avoid unintentional indirect effects. We conclude that, in prebreeding programs, it could be worthy to use large effective numbers to prevent inbreeding depression, particularly when the objective is the direct use of improved landraces. Another conclusion is that recurrent selection does not seem to be as efficient on European germplasm as it is on Corn Belt varieties. Finally, to obtain valuable new germplasm requires a sustained, long-term effort.