Development of Extra-Early Provitamin A Quality Protein Maize Inbreds with Resistance/Tolerance to <i>Striga hermonthica</i> and Soil Nitrogen Stress
2021
Solomon A. Oyekale | Baffour Badu-Apraku | Victor O. Adetimirin | Nnanna Unachukwu | Melaku Gedil
A hemiparasitic plant, <i>Striga hermonthica</i> (Del.) Benth and soil nitrogen stress are the key constraints to maize (<i>Zea mays</i> L.) productivity in sub-Saharan Africa, where commonly cultivated maize is the normal endosperm type that is deficient in provitamin A, tryptophan and lysine (PVATL). Seventy-six extra-early maize inbreds with provitamin A, tryptophan, and lysine qualities (TZEEIORQ) were developed to address these constraints, and four checks were assessed under <i>Striga</i>, low and high nitrogen conditions at three locations in Nigeria. The inbreds were further genotyped with two beta-carotene hydroxylase 1 (crtRB1) markers, and their seeds were quantified for provitamin A content. Significant (<i>p</i> < 0.01) genetic variations were observed for grain yield and other agronomic attributes of the inbreds under varying environmental conditions. Levels of PVATL for the inbreds ranged from 2.21–10.95 µg g<sup>−1</sup>, 0.04–0.08%, and 0.19–0.39%, respectively. Beta-carotene marker, crtRB1-3′TE, was polymorphic and grouped the inbreds into two. The marker was effective in identifying inbreds with moderate provitamin A content. Inbreds TZEEIORQ 5, TZEEIORQ 52, and TZEEIORQ 55 exhibited resistance to <i>Striga</i>, tolerance to nitrogen stress with moderate levels of PVATL and could be invaluable sources of favorable alleles for breeding nutritionally improved maize varieties with resistance/tolerance to <i>Striga</i> and soil nitrogen stress.
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