Abstract
Abstract Background Increasing zinc (Zn) concentrations in maize grains could contribute to alleviating widespread human Zn deficiency in sub-Saharan Africa (SSA). However, trade-offs between grain Zn concentrations and maize yields have been observed. Scope Using data from researcher-managed, on-farm and on-station field trials in Kenya, Zambia and Zimbabwe, we aimed (i) to confirm whether this trade-off is found in current farming systems in SSA and (ii) to explore whether genotypic and management options, relevant for the African context, can increase both yields and grain Zn concentrations across several environments. Results An overall negative, but weak relation between maize yields and grain Zn concentrations was found. High yields and high grain Zn concentrations did not co-occur. The negative relation between grain Zn concentrations and yields cannot be bypassed by selecting one of the commercially available varieties used in this study. Nitrogen application increased yields, but had contrasting effects on grain Zn concentrations depending on variety and site. Grain Zn concentrations were positively related with soil organic carbon and P and K availability. Conclusions Attaining grain Zn concentrations above the HarvestPlus target of 38 mg kg −1 , considered adequate for reducing human Zn deficiency, with current commercially available maize varieties and presented management options, is not possible without compromising yield levels. Increasing soil organic matter content and balanced application of N, P and K fertilisers could increase grain Zn concentrations. These practices likely will also increase yields and could be a viable option to bypass the trade-off between maize yields and grain Zn concentrations.
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Claims 8
Claim · model-written summary
An overall negative but weak relation was found between maize yields and grain Zn concentrations.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“An overall negative, but weak relation between maize yields and grain Zn concentrations was found”
Claim · model-written summary
High maize yields and high grain Zn concentrations did not co-occur.
- Outcome
- High yields and high grain Zn concentrations did not co-occure1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize yields”
e1“High yields and high grain Zn concentrations did not co-occur”
Claim · model-written summary
The negative relation between grain Zn and yield cannot be bypassed by selecting one of the commercially available varieties used in the study.
- Outcome
- negative relation between grain Zn concentrations and yieldse1
- Qualifier
- cannot be bypassed by selecting one of the commercially available varietiese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize yields”
e1“The negative relation between grain Zn concentrations and yields cannot be bypassed by selecting one of the commercially available varieties”
Claim · model-written summary
Nitrogen application increased maize yields.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize yields”
e1“Nitrogen application increased yields”
Claim · model-written summary
Nitrogen application had contrasting effects on grain Zn concentrations depending on variety and site.
- Treatment
- Nitrogen applicatione1
- Outcome
- grain Zn concentrationse1
- Direction
- contrasting effectse1
- Qualifier
- depending on variety and sitee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize yields”
e1“Nitrogen application increased yields, but had contrasting effects on grain Zn concentrations depending on variety and site”
Claim · model-written summary
Grain Zn concentrations were positively related with soil organic carbon and P and K availability.
- Compound
- soil organic carbon and P and K availabilitye1
- Outcome
- Grain Zn concentrationse1
- Direction
- increaseinferrede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize yields”
e1“Grain Zn concentrations were positively related with soil organic carbon and P and K availability”
Claim · model-written summary
Attaining grain Zn above the HarvestPlus target of 38 mg/kg with current commercial maize varieties and presented management options is not possible without compromising yield.
- Outcome
- Attaining grain Zn concentrations above the HarvestPlus targete1
- Value
- 38 mg kg −1e1
- Qualifier
- not possible without compromising yield levelse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Attaining grain Zn concentrations above the HarvestPlus target of 38 mg kg −1 , considered adequate for reducing human Zn deficiency, with current commercially available maize varieties and presented management options, is not possible without compromising yield levels”
Claim · model-written summary
Increasing soil organic matter and balanced application of N, P and K fertilisers could increase grain Zn concentrations in maize.
- Outcome
- increase grain Zn concentrationse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize yields”
e1“Increasing soil organic matter content and balanced application of N, P and K fertilisers could increase grain Zn concentrations”
The same questions in other papers
nitrogen · yield · Zea mays (maize)Positive and negative results
1,905 papers in the same direction as this paper · 234 in the opposite direction · 45 reporting no difference from an alternative
- no effect
- positive
- negative
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