Abstract
Abstract Landraces of maize ( Zea mays L.) have a variability not found in the elite hybrids due to the bottleneck during selection. There is a renewed interest in using that variability, incorporating alleles for specific traits, or widening 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 agriculture that preserves crop diversity. Pre-breeding programs are aimed to reduce the yield gap among landraces and improved materials. In the Misión Biológica de Galicia we have carried out three cycles of a S 1 recurrent selection program for yield on four local landraces from Northwestern Spain with the objective of obtaining improved populations that might be cultivated by farmers and that could be used as sources of superior inbred lines. One hundred plants were selfed in each landrace and the S 1 families were evaluated in a 10 × 10 simple lattice. The 20 S 1 families with the highest grain yields were randomly intercrossed to form the selected population of each landrace. After three cycles of selection, each population and its cycles of selection were evaluated in three locations for two years. All the populations had a consistent yield gain in the first cycle of selection. However, the response in later cycles differed among the populations: one population had a continuous increase of 21% per cycle while two populations had a reduced yield in the last cycles. Our results highlight the need to include secondary traits to avoid unintentional indirect effects. We conclude that, in pre-breeding 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, obtaining valuable new germplasm requires a sustained, long-term effort.
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Claims 7
Claim · model-written summary
All four maize populations had a consistent yield gain in the first cycle of selection.
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e1“All the populations had a consistent yield gain in the first cycle of selection”
Claim · model-written summary
One maize population had a continuous yield increase of 21% per cycle of selection.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e1“one population had a continuous increase of 21% per cycle”
Claim · model-written summary
Two maize populations had reduced yield in the last cycles of selection.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e1“two populations had a reduced yield in the last cycles”
Claim · model-written summary
Recurrent selection does not seem to be as efficient on European germplasm as on Corn Belt varieties.
Verbatim
e1“recurrent selection does not seem to be as efficient on European germplasm as it is on Corn Belt varieties”
Claim · model-written summary
In pre-breeding programs it could be worthwhile to use large effective numbers to prevent inbreeding depression, particularly for direct use of improved landraces.
- Outcome
- prevent inbreeding depressione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e1“in pre-breeding programs, it could be worthy to use large effective numbers to prevent inbreeding depression”
Claim · model-written summary
The results highlight the need to include secondary traits to avoid unintentional indirect effects.
- Outcome
- unintentional indirect effectse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e1“Our results highlight the need to include secondary traits to avoid unintentional indirect effects”
Claim · model-written summary
Obtaining valuable new germplasm requires a sustained, long-term effort.
- Outcome
- obtaining valuable new germplasme1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e1“obtaining valuable new germplasm requires a sustained, long-term effort”