Maize (Zea mays L.), an important staple crop in West and Central Africa (WCA), has enormous potential to reduce food insecurity in this subregion. Research covering three periods or eras of breeding has been conducted to develop cultivars resistant/tolerant to three maize stress factors: Striga parasitism, drought, and low soil nitrogen. A study was conducted under optimal or natural growing environments at 35 locations in WCA for 2 yr to determine genetic improvement in grain yield of the maize cultivars developed during the three breeding periods: 1988–2000 (period 1), 2001–2006 (period 2), and 2007–2010 (period 3). The average rate of increase in grain yield under optimum growing conditions was 40 kg ha−1 yr−1 with a genetic gain of 1.3% yr−1, which was slightly higher than the gain of 30 kg ha−1 yr−1, an annual genetic gain of 1.2% across 16 stress environments. It was concluded that substantial improvement in the yield potential of early maize under relatively nonstress environmental conditions has been made in this subregion by breeding for stress tolerance during the past three decades. The varieties EV DT‐W 2008 STR, 2009 DTE‐Y STR Syn, and TZE‐W DT C2 STR, all from the latest era of improvement, were identified as the highest yielding and most stable cultivars and should be promoted to contribute to food security in this subregion.

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Identification of outstanding maize (Zea mays L.) hybrids for target environments is complicated by genotype × environment interactions. Thirty‐two early‐maturity maize hybrids were evaluated at eight locations in Nigeria and six locations in Ghana for 2 yr to (i) identify high‐yielding, stable hybrids across locations and/or hybrids specifically adapted to different locations, and (ii) identify ideal test sites for selection of superior hybrids in the two countries. Genotype, country, year, location (country), and their interactive effects were significant (P < 0·01) for grain yield, days to anthesis and silking, anthesis‐silking interval, plant and ear aspects, and ears per plant. Mean grain yield of the hybrids ranged from 3177 kg ha−1 for EWH‐5 to 4596 kg ha−1 for EWH‐29. The genotype main effects plus genotype × environment interaction (GGE) biplot analysis revealed that EWH‐29, EWH‐8, and EWH‐30 did not differ significantly in grain yield and were the most stable hybrids in both countries, whereas EWH‐26 and EWH‐32 were the most stable hybrids only in Ghana. The GGE biplot analysis identified Samaru, Kafin Soli, and Minjibir in Nigeria and Nyankpala, Damongo, and Fumesua in Ghana as the most discriminating locations. Minjibir (Nigeria) and Nyankpala (Ghana), being most discriminating and representative locations, were considered the ideal testing sites for the respective countries. The type of cultivars evaluated determined the most suitable locations for multilocation testing within Ghana and Nigeria. Whereas hybrids EWH‐29, EWH‐8, and EWH‐30 should be suitable for production in Nigeria, EWH‐26 and EWH‐32 should be promoted for production in Ghana.