Evaluation of early maturing provitamin a maize hybrids for yield and agronomic performance under different environments in Zimbabwe

Abstract

Maize (Zea mays L) is the major staple food in sub-Saharan Africa, including Zimbabwe but is nutritionally deficient in provitamin A which has led to high levels of vitamin A deficiency (VAD) in Zimbabwe. Provitamin A (PVA) biofortified maize with high carotenoid content was developed to curb vitamin A deficiency (VAD) but adoption has been constrained by perceptions that biofortified hybrids yield less than conventional maize. This research evaluated grain yield and agronomic performance of twenty-one newly developed early maturing CIMMYT provitamin A maize hybrids alongside four checks (ZS242, ZS244, ZS500 and CZH1815A) to identify superior genotypes for further testing and release. Trials were conducted at three research stations in Zimbabwe (Harare, Gwebi and Rattray Arnold). They comprised of seven environments representing optimum management, low nitrogen stress and combined Grey Leaf Spot (GLS) and Exserohilum turcicum (ET) disease inoculated environment. The results showed that genotype, environment and genotype x environment (G X E) interaction effects were highly significant for grain yield and several traits. Under optimum conditions, the top hybrids DSH24135 (7.81 t/ha), DSH24137 (7.79 t/ha) and DSH24139 (7.45 t/ha) were above commercial check, ZS500 (7.28 t/ha). Low-nitrogen stress reduced mean grain yield by approximately 57%, with DSH24147 (4.29 t/ha) and DSH24132 (3.79 t/ha) showing the greatest nitrogen-stress tolerance. Under disease pressure DSH24142 (4.96 t/ha) and DSH24137 (4.86 t/ha) combined high yield with low disease severity. GGE biplot analysis identified DSH24133 and DSH24139 as the most stable, high-yielding genotypes across two distinct mega-environments. DSH24135, DSH24137 and DSH24139 are recommended for advancement to further multi-location trials