Abstract
Fertilizer-based biofortification is a strategy for combating worldwide malnutrition of zinc (Zn), iron (Fe) and selenium (Se). Field experiments were conducted to investigate the effects of foliar treatments on concentrations of Zn, Fe, Se, N and bioavailability of Zn and Fe in grains of three maize cultivars grown at three locations. We compared the efficacy of ZnO nanoparticles (ZnO-NPs), Zn complexed chitosan nanoparticles (Zn-CNPs), conventional ZnSO 4 and a cocktail solution (containing Zn, Fe and Se). All treatments were foliar-applied at rate of 452 mg Zn L –1 , plus urea. Applying ten-fold less Zn (at rate of 45.2 mg Zn L –1 ) plus urea in the form of ZnO-NPs, Zn-CNPs, or ZnSO 4 resulted in no increase, or a negligible increase, in grain Zn concentration compared with deionized water. By contrast, among the different Zn sources plus urea applied by foliar sprays, conventional ZnSO 4 was the most efficient in improving grain Zn concentration. Furthermore, foliar application of a cocktail solution effectively improved grain concentrations of Zn, Fe, Se and N simultaneously, without a grain yield trade-off. For example, the average grain concentrations were simultaneously increased from 13.8 to 22.1 mg kg –1 for Zn, from 17.2 to 22.1 mg kg –1 for Fe, from 21.4 to 413.5 ug kg –1 for Se and from 13.8 to 14.7 g kg –1 for N by foliar application of a cocktail solution. Because grain yield was significantly negatively correlated with grain nutrient concentrations, the magnitude of increase in grain concentrations of Zn and Fe was most pronounced in the maize cultivar with the lowest grain yield (Zhengdan958 grown in Linyi). Foliar application of a cocktail solution also significantly decreased the phytic acid (PA) concentration, ratios of PA/Fe and PA/Zn in grains, indicating an increased bioavailability of Fe and Zn for human health. In conclusion, we found that a foliar application of a cocktail solution including Zn, Fe, Se and N was most effective for biofortification, but that the grains with the lowest yield contained the greatest concentration of these elements. This finding highlights the need to breed maize varieties that are capable of achieving both high grain yield and high grain nutritional quality to address food security and human health challenges.
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Claims 13
Claim · model-written summary
Low rate ZnO nanoparticles gave no or negligible grain Zn increase over water.
- Treatment
- ZnO-NPse0
- Outcome
- grain Zn concentratione0
- Direction
- no increasee0
- Qualifier
- 45.2 mg Zn L –1e0
- Comparator
- deionized watere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“Applying ten-fold less Zn (at rate of 45.2 mg Zn L –1 ) plus urea in the form of ZnO-NPs, Zn-CNPs, or ZnSO 4 resulted in no increase, or a negligible increase, in grain Zn concentration compared with deionized water.”
Claim · model-written summary
Low rate Zn chitosan nanoparticles gave no or negligible grain Zn increase over water.
- Treatment
- Zn-CNPse0
- Outcome
- grain Zn concentratione0
- Direction
- no increasee0
- Qualifier
- 45.2 mg Zn L –1e0
- Comparator
- deionized watere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“Applying ten-fold less Zn (at rate of 45.2 mg Zn L –1 ) plus urea in the form of ZnO-NPs, Zn-CNPs, or ZnSO 4 resulted in no increase, or a negligible increase, in grain Zn concentration compared with deionized water.”
Claim · model-written summary
Low rate zinc sulfate gave no or negligible grain Zn increase over water.
- Treatment
- ZnSO 4e0
- Outcome
- grain Zn concentratione0
- Direction
- no increasee0
- Qualifier
- 45.2 mg Zn L –1e0
- Comparator
- deionized watere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“Applying ten-fold less Zn (at rate of 45.2 mg Zn L –1 ) plus urea in the form of ZnO-NPs, Zn-CNPs, or ZnSO 4 resulted in no increase, or a negligible increase, in grain Zn concentration compared with deionized water.”
Claim · model-written summary
Conventional zinc sulfate most efficiently raised grain Zn among foliar Zn sources.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“conventional ZnSO 4 was the most efficient in improving grain Zn concentration.”
Claim · model-written summary
Foliar cocktail increased grain Zn concentration from 13.8 to 22.1 mg kg –1.
- Treatment
- foliar application of a cocktail solutione0
- Outcome
- grain concentrationse0
- Direction
- increasede0
- Value
- 22.1 mg kg –1e0
- Qualifier
- Zne0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“the average grain concentrations were simultaneously increased from 13.8 to 22.1 mg kg –1 for Zn, from 17.2 to 22.1 mg kg –1 for Fe, from 21.4 to 413.5 ug kg –1 for Se and from 13.8 to 14.7 g kg –1 for N by foliar application of a cocktail solution.”
Claim · model-written summary
Foliar cocktail increased grain Fe concentration from 17.2 to 22.1 mg kg –1.
- Treatment
- foliar application of a cocktail solutione0
- Outcome
- grain concentrationse0
- Direction
- increasede0
- Value
- 22.1 mg kg –1e0
- Qualifier
- Fee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“the average grain concentrations were simultaneously increased from 13.8 to 22.1 mg kg –1 for Zn, from 17.2 to 22.1 mg kg –1 for Fe, from 21.4 to 413.5 ug kg –1 for Se and from 13.8 to 14.7 g kg –1 for N by foliar application of a cocktail solution.”
Claim · model-written summary
Foliar cocktail increased grain Se concentration from 21.4 to 413.5 ug kg –1.
- Treatment
- foliar application of a cocktail solutione0
- Outcome
- grain concentrationse0
- Direction
- increasede0
- Value
- 413.5 ug kg –1e0
- Qualifier
- See0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“the average grain concentrations were simultaneously increased from 13.8 to 22.1 mg kg –1 for Zn, from 17.2 to 22.1 mg kg –1 for Fe, from 21.4 to 413.5 ug kg –1 for Se and from 13.8 to 14.7 g kg –1 for N by foliar application of a cocktail solution.”
Claim · model-written summary
Foliar cocktail increased grain N concentration from 13.8 to 14.7 g kg –1.
- Treatment
- foliar application of a cocktail solutione0
- Outcome
- grain concentrationse0
- Direction
- increasede0
- Value
- 14.7 g kg –1e0
- Qualifier
- Ne0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“the average grain concentrations were simultaneously increased from 13.8 to 22.1 mg kg –1 for Zn, from 17.2 to 22.1 mg kg –1 for Fe, from 21.4 to 413.5 ug kg –1 for Se and from 13.8 to 14.7 g kg –1 for N by foliar application of a cocktail solution.”
Claim · model-written summary
Foliar cocktail caused no grain yield trade-off.
- Treatment
- foliar application of a cocktail solutione0
- Outcome
- grain yielde0
- Direction
- without a grain yield trade-offe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“foliar application of a cocktail solution effectively improved grain concentrations of Zn, Fe, Se and N simultaneously, without a grain yield trade-off.”
Claim · model-written summary
Grain yield was significantly negatively correlated with grain nutrient concentrations.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“grain yield was significantly negatively correlated with grain nutrient concentrations”
Claim · model-written summary
Grain Zn and Fe increases were greatest in low yielding Zhengdan958 grown in Linyi.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“the magnitude of increase in grain concentrations of Zn and Fe was most pronounced in the maize cultivar with the lowest grain yield (Zhengdan958 grown in Linyi)”
Claim · model-written summary
Foliar cocktail significantly decreased grain phytic acid and its Fe and Zn ratios.
- Treatment
- Foliar application of a cocktail solutione0
- Outcome
- phytic acid (PA) concentration, ratios of PA/Fe and PA/Zn in grainse0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“Foliar application of a cocktail solution also significantly decreased the phytic acid (PA) concentration, ratios of PA/Fe and PA/Zn in grains”
Claim · model-written summary
The authors call for maize varieties combining high yield and grain nutritional quality.
- Outcome
- breed maize varieties that are capable of achieving both high grain yield and high grain nutritional qualitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
t0“maize cultivars”
e0“need to breed maize varieties that are capable of achieving both high grain yield and high grain nutritional quality”
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