Heritability and expression of Fe and Zn and their bioavailability in South African maize under low N stress conditions

TIron (Fe) deficiency affects 4-5 billion people in the
world while zinc (Zn) deficiency affects 49% of the
world population, especially in low-income countries.
Therefore, the objective of the present study was to assess
heritability and expression of Fe and Zn and their
bioavailability in maize under abiotic stress and optimal
conditions. Maize germplasm provided by the GCI-ARC
Potchefstroom was screened for Fe and Zn content and
nine parents (three males and six females) were selected
for low, medium and high Fe and Zn concentration.
These parents were grown at Makhathini Research Station
and crossed in a line × tester (6 × 3) design, and 18
hybrids were generated. These hybrids along with parents
were planted in Potchefstroom, Vaalharts and Cedara under
optimum and low N conditions using an alpha lattice
design with three replications. Combined analysis of
variance revealed that genotype and location significantly
affected the expression of Zn under low N conditions and
expression of Fe under optimal conditions. Genotype by
location interaction was significant for phytic acid contents
under both abiotic stress and optimum conditions.
The range of Fe, Zn and phytic acid contents under low
N conditions was 11.25-19.25 mg/kg; 12.88 -24.39 mg/
kg; 4.49 -6.74 µmol/ml, and under optimum conditions
11.87-16.77 mg/kg; 17.02-21.63 mg/kg; and 4.29 -5.78
µmol/ml, respectively. SMH1 maize hybrid had high
Fe (18.38 mg/kg) and Zn (15.73 mg/kg) and low phytic
acid (4.82 µmol/ml), indicating high bioavailability in
humans, under low N conditions. SMH18 maize hybrid
had high Fe (15.63 mg/kg), Zn (20.38 mg/kg) and low
phytic acid (4.29 µmol/ml) under optimum conditions.
The heritability of Fe and Zn under low N conditions was
47% and 21% and under optimal conditions it was 52%
and 44%, respectively, indicating that low N conditions
significantly reduced heritability of zinc.

Author(s): Sajjad Akhtar, M.T. Labuschagne, K. Mashingaidze, G. Osthoff

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