Table 1 Implementation of key breeding tools/processes to improve genetic gains in CIMMYT’s tropical maize breeding pipelines.
From: Genetic trends in CIMMYT’s tropical maize breeding pipelines
Eastern Africa | Southern Africa | South Asia | Latin America | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
EA-PP1 | EA-PP2 | EA-PP3 | SA-PP1 | SA-PP2 | SAWLDT | SAHDT | SADT | LatAmTL | LatAmTM | |
Product profiles refined and aligned across CIMMYT, NARS and SMEs | 2019 | 2019 | 2019 | 2019 | 2019 | 2019 | 2019 | 2019 | 2019 | 2019 |
Implementation of sparse phenotyping | 2021 | 2021 | 2022 | 2021 | 2022 | 2022 | 2021 | 2022 | – | – |
Use of selection index at early stages of breeding for selecting parents for recycling | 2021 | 2021 | 2022 | 2022 | 2022 | 2022 | 2022 | 2022 | 2021 | 2021 |
Current breeding cycle time (in years) | 4 (recycling parents after Stage 2 testing) | 4 (recycling parents after Stage 2 testing) | 5 (recycling parents after Stage 3 testing) | 4 (recycling parents after Stage 2 testing) | 4 (recycling parents after Stage 2 testing) | 5 years (recycling parents after Stage 3 testing) | 4.5 years (recycling parents after Stage 2 testing) | 5 years (recycling parents after Stage 3 testing) | 4 (recycling parents after Stage 2 testing) | 4 (recycling parents after Stage 2 testing) |
Level of integration of DH technology in breeding pipelines | 80% | 70% | 30% | 60% | 60% | 50% | 80% | 10% | 50% | 50% |
Rapid generation advancement through three-season nurseries per year | 2021: 2.5 seasons/year; From 2022: 3 seasons/year (after the seed dryer installation) | 2021: 2.5 seasons/year; From 2022: 3 seasons/year (after the seed dryer installation) | 2021: 2 seasons/year | 2021: 2.5 seasons/year; From 2022: 3 seasons/year (after the seed dryer installation) | 2021: 2.5 seasons/year; From 2022: 3 seasons/year (after the seed dryer installation) | 2021: 2 seasons/year | 2021: 2 seasons/year | 2021: 2 seasons/year | 2.5 seasons/year | 2.5 season/year |
Marker-assisted forward breeding | MSV; MLN | MSV; MLN | MLN | MSV | MSV | Initiated for TLB in 2021 | Not implemented | Initiated for TLB in 2021 | TSC | PVA; MSV |
Genomic prediction (Test half-Predict half) | Since 2017 (all Stage 1 genotyped with mid-density markers); selection of individuals for the next stage of testing based on GEBVs and GBLUPs | Since 2017 (all Stage 1 genotyped with mid-density markers); selection of individuals for the next stage of testing based on GEBVs and GBLUPs | All Stage 1 genotyped with mid-density markers in 2021, and GEBVs estimated for selection of lines for the next stage of testing | All Stage 1 genotyped with mid-density markers in 2021, and GEBVs estimated for selection of lines for the next stage of testing | Not started | Not started | Being implemented since 2019 | Not started | From 2015 to 2020, (all Stage 1 genotyped with mid to high-density markers); selection of individuals for the next stage of testing based on GEBVs and GBLUPs) | Proof-of-Concept (2019) |
Rapid cycle genomic selection (RCGS) | Being implemented | Being initiated in 2022 | Not started | Being initiated in 2022 | Being initiated in 2022 | Implemented for two multi parent populations during 2010–2013 | Implemented for six multi-parent populations during 2014–2017 | Implemented 2 cycles for six populations during 2010–2013 | Tested from 2010 to 2015; Being initiated in 2022 | Being initiated in 2022 |
Molecular markers-based QA/QC in CGIAR, NARS & selected SMEs | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
Implementing high-throughput field-based phenotyping | Being initiated in 2022 (PH, EH) | Being initiated in 2022 (PH, EH) | Being initiated in 2022 (PH, EH) | Being implemented (PH, EH) | Being implemented (PH, EH) | Implemented till Dec, 2021 (PH, AD) | Implemented till Dec, 2021 (PH, AD) | Not started | UAVs tested for drought stress | UAVs tested for drought stress |
Joint CGIAR-NARS annual stage-gate advancement meetings | Yes | Yes | Yes | Yes | Yes | To be implemented | To be implemented | To be implemented | Yes | Yes |
