Abstract
Low grain yield and recurrent drought remain major constraints to maize production in Sub-Saharan Africa (SSA), underscoring the urgent need for hybrids with improved resilience. The use of ex-PVP (expired Plant Variety Protection) temperate maize lines is important to improve yield potential and genetic diversity in tropical adapted lines. In this study, 15 temperate introgressed lines and 6 tropical lines were crossed with eight single cross testers to generate 168 testcross hybrids. All genotypes were evaluated in 8 sites, with 6 well-watered (WW) and 2 drought-stressed (DS) conditions in Kenya. Analysis showed significant genotypic and site effects for grain yield (GY) and other agronomic traits, with strong genotype × environment interactions under drought. General combining ability (GCA) and specific combining ability (SCA) were important, with additive variance dominating under both WW and DS. Temperate introgression (TI) improved yield performance in most tropical backgrounds, with hybrids from TI outperforming tropical hybrids by 1.20-2.04 t/ha under optimal conditions and yielding similarly under drought stress (TI, 1.88 t/ha; tropical, 1.89 t/ha). Hybrids showed up to 74% reduction in GY, 22% lower PH, 18% lower EH, and a 72% increase in ASI under DS compared to WW. Lines L2, L10, L16 and testers T1, T2, T3, T4, T7 showed consistently positive GCA for GY and shorter anthesis-silking interval, suggesting they can be used in breeding programs to develop high yielding drought tolerant hybrids suitable for sub-Saharan Africa. These findings emphasize the value of ex-PVP lines as source to enhance yield in tropical adapted germplasm. Both additive and non-additive gene action are important, combining pedigree methods with genomic selection for additive effects along with strategic heterosis use can accelerate the development of high-yielding, climate-resilient maize hybrids for stress-prone regions of SSA.
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Claims 14
Claim · model-written summary
Maize grain yield and agronomic traits had significant genotypic and site effects.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Analysis showed significant genotypic and site effects for grain yield (GY) and other agronomic traits”
t0“maize”
Claim · model-written summary
Genotype by environment interactions were strong under drought.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“strong genotype × environment interactions under drought”
t0“maize”
Claim · model-written summary
Additive variance dominated combining ability under well-watered and drought conditions.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“General combining ability (GCA) and specific combining ability (SCA) were important, with additive variance dominating under both WW and DS.”
t0“maize”
Claim · model-written summary
Temperate introgression improved yield in most tropical backgrounds.
- Treatment
- Temperate introgression (TI)e0
- Outcome
- yield performancee0
- Direction
- improvede0
- Qualifier
- in most tropical backgroundse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Temperate introgression (TI) improved yield performance in most tropical backgrounds”
t0“maize”
Claim · model-written summary
Temperate introgressed hybrids yielded 1.20-2.04 t/ha more than tropical hybrids under optimal conditions.
- Treatment
- hybrids from TIe0
- Outcome
- outperforming tropical hybridse0
- Direction
- outperforminge0
- Value
- 1.20-2.04 t/hae0
- Qualifier
- under optimal conditionse0
- Comparator
- tropical hybridse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“hybrids from TI outperforming tropical hybrids by 1.20-2.04 t/ha under optimal conditions”
t0“maize”
Claim · model-written summary
Temperate introgressed and tropical hybrids yielded similarly under drought, at 1.88 and 1.89 t/ha respectively.
- Treatment
- TIe0
- Outcome
- yieldinge0
- Direction
- similarlye0
- Value
- 1.88 t/hae0
- Qualifier
- tropical, 1.89 t/hae0
- Comparator
- tropicale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“yielding similarly under drought stress (TI, 1.88 t/ha; tropical, 1.89 t/ha)”
t0“maize”
Claim · model-written summary
Drought reduced hybrid grain yield by up to 74% relative to well-watered conditions.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Hybrids showed up to 74% reduction in GY, 22% lower PH, 18% lower EH, and a 72% increase in ASI under DS compared to WW.”
t0“maize”
Claim · model-written summary
Drought lowered hybrid plant height by 22%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Hybrids showed up to 74% reduction in GY, 22% lower PH, 18% lower EH, and a 72% increase in ASI under DS compared to WW.”
t0“maize”
Claim · model-written summary
Drought lowered hybrid ear height by 18%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Hybrids showed up to 74% reduction in GY, 22% lower PH, 18% lower EH, and a 72% increase in ASI under DS compared to WW.”
t0“maize”
Claim · model-written summary
Drought increased anthesis-silking interval by 72%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Hybrids showed up to 74% reduction in GY, 22% lower PH, 18% lower EH, and a 72% increase in ASI under DS compared to WW.”
t0“maize”
Claim · model-written summary
Lines L2, L10 and L16 showed consistently positive general combining ability for yield and shorter anthesis-silking interval.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lines L2, L10, L16 and testers T1, T2, T3, T4, T7 showed consistently positive GCA for GY and shorter anthesis-silking interval”
t0“maize”
Claim · model-written summary
Testers T1, T2, T3, T4 and T7 showed consistently positive general combining ability for yield and shorter anthesis-silking interval.
- Material
- testers T1, T2, T3, T4, T7e0
- Outcome
- positive GCA for GY and shorter anthesis-silking intervale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lines L2, L10, L16 and testers T1, T2, T3, T4, T7 showed consistently positive GCA for GY and shorter anthesis-silking interval”
t0“maize”
Claim · model-written summary
The authors suggest the selected lines and testers for breeding high-yielding drought-tolerant hybrids.
- Outcome
- used in breeding programs to develop high yielding drought tolerant hybridse0
- Setting
- sub-Saharan Africae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suggesting they can be used in breeding programs to develop high yielding drought tolerant hybrids suitable for sub-Saharan Africa”
t0“maize”
Claim · model-written summary
The authors propose combining pedigree methods, genomic selection and heterosis use to accelerate resilient maize hybrid development.
- Outcome
- combining pedigree methods with genomic selection for additive effects along with strategic heterosis usee0
- Setting
- stress-prone regions of SSAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“combining pedigree methods with genomic selection for additive effects along with strategic heterosis use can accelerate the development of high-yielding, climate-resilient maize hybrids for stress-prone regions of SSA”
t0“maize”
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See all 5 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.