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Testing and identification of high-yielding and stable hybrids adapted to contrasting environments is crucial for sustainable maize (Zea mays L.) production in sub-Saharan Africa. The objectives of this study were to (i) assess the yield response of 150 single-cross hybrids under low soil nitrogen (low-N), Striga-infested and optimal growing environments, and (ii) identify the most suitable environments for the selection of superior and stable hybrids. The 150 hybrids were derived from 30 inbred parents via North Carolina design II mating scheme. They were tested, together with six checks, in a 13 × 12 alpha lattice design with two replications across 10 test environments in 2016 and 2017. Genotype by environment interaction was significant for yield, with high repeatability (0.70) across the test environments. Test environments KWDS-LN-16 and KWDS-OPT-16 were found to be the ideal test environments for selecting superior hybrids. About 62% of the hybrids were stable across environments. Hybrids TZEI 3A × TZdEI 192, TZdEI 216 × TZEI 3A and TZEI 379 × TZdEI 272 were identified as high yielding and most stable across environments. These outstanding hybrids with tolerance to both Striga and low-N should be further tested extensively on-farm for potential release in Ghana and other West African countries.

Maize is a major staple food in sub-Saharan Africa. However, due to the threats posed by biotic and abiotic constraints to its production, it is a prerequisite to conserve germplasm with diverse genetic background and to seek for favourable genotypes with such background for improvement of superior genotypes. This study assessed the diversity of 70 white maize populations developed at CSIR-Savanna Agricultural Research Institute with resistance/tolerance to drought and low soil nitrogen (Low-N) using 31 SSR markers. A total of 288 alleles were detected among the germplasm used with a range of 4 to 17 alleles per locus and an average allele number of 9.60 alleles per locus. Polymorphic Information Content values for the SSR markers ranged from 0.32 to 0.85 with a mean value of 0.68. The average heterozygosity obtained from the markers was 0.54 and gene diversity ranged from 0.35 to 0.87 with a mean gene diversity value of 0.71 indicating a high level of polymorphism among the populations. Clustering based on Jaccard's similarity coefficient and an Unweighted Pair Group Method with Arithmetic Mean (UPGMA) revealed 5 clusters for the 70 populations. Evanno method for population structure clustering further revealed two sub-populations. Sub-population 1 was more genetically diverse with an Fst value of 0.18 than sub-population 2 which recorded an Fst value of 0.013. These results indicated that the SSR used were very polymorphic for diversity studies. Also, the studied maize populations are diverse and heterozygous, making them ideal source populations for extraction of drought and low-N tolerant inbred lines. Keywords: Drought, Polymorphic, Diversity, Microsatellite, Heterozygosity

Plant breeders’ knowledge of precise traits preferred by variety users would accelerate varietal turnover and widen adoption of newly developed maize varieties in Ghana. The objective of this research was to provide empirical evidence of trait preferences of farmers and other actors in the maize value chain in northern Ghana, based on which research strategies for maize improvement could be formulated. Participatory rural appraisal was conducted in 2016 to determine key traits preferred by maize value chain actors across the three regions in northern Ghana. A total of 279 maize value chain actors were interviewed. Different scoring and ranking techniques were used to assess the maize traits preferred by the different actors. Participatory variety selection trials were also conducted in the Tolon, West Gonja, Binduri, and Sissala East districts in northern Ghana from 2014 to 2016. The mother-baby trial approach was used to evaluate eight hybrids with 3000 farmers. Data on yield and agronomic performance of the hybrids and farmer’s selection criteria were collected. Data analyses were performed using GenStat Edition 16 and SPSS Edition 20 statistical packages. The participatory rural appraisal method identified farmers, input dealers, traders, and processors as the primary maize value chain actors in the study areas. Trait preferences of the different actors overlapped and revolved around grain quality including nutritional value, and stress tolerance and grain yield. Results of the participatory variety selection study revealed that across districts, farmers preferred high-yielding varieties with multiple cobs per plant, white grain endosperm color, and bigger and fully filled cobs. For the first time, our holistic assessment of the trait preferences of key actors of the maize value chain in northern Ghana revealed a comprehensive list of traits, which could be used by breeders to develop varieties that may be preferred by all value chain actors in northern Ghana. Supplementary Information The online version contains supplementary material available at 10.1007/s13593-021-00708-w.

Maize is a food security crop cultivated in the African savannas that are vulnerable to the occurrence of drought stress and Striga hermonthica infestation. The co-occurrence of these stresses can severely damage crop growth and productivity of maize. Until recently, maize breeding in International Institute of Tropical Agriculture (IITA) has focused on the development of either drought tolerant or S. hermonthica resistant germplasm using independent screening protocols. The present study was therefore conducted to examine the extent to which maize hybrids simultaneously expressing resistance to S. hermonthica and tolerance to drought (DTSTR) could be developed through sequential selection of parental lines using the two screening protocols. Regional trials involving 77 DTSTR and 22 commercial benchmark hybrids (STR and non-DTSTR) were then conducted under Striga-infested and non-infested conditions, managed drought stress and fully irrigated conditions as well as in multiple rainfed environments for 5 years. The observed yield reductions of 61% under managed drought stress and 23% under Striga-infestation created desirable stress levels leading to the detection of significant differences in grain yield among hybrids at individual stress and non-stress conditions. On average, the DTSTR hybrids out-yielded the STR and non-DTSTR commercial hybrids by 13–19% under managed drought stress and fully irrigated conditions and by −4 to 70% under Striga-infested and non-infested conditions. Among the DTSTR hybrids included in the regional trials, 33 were high yielders with better adaptability across environments under all stressful and non-stressful testing conditions. Twenty-four of the 33 DTSTR hybrids also yielded well across diverse rainfed environments. The genetic correlations of grain yield under managed drought stress with yield under Striga-infestation and multiple rainfed environments were 0.51 and 0.57, respectively. Also, a genetic correlation between yields under Striga-infestation with that recorded in multiple rainfed environments was 0.58. These results suggest that the sequential selection scheme offers an opportunity to accumulate desirable stress-related traits in parents contributing to superior agronomic performance in hybrids across stressful and diverse rainfed field environments that are commonly encountered in the tropical savannas of Africa.

Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), was first detected in Africa in 2016. Efforts at controlling it have been challenged by the many unknowns about this invasive insect. The population dynamics of FAW moths and the damage caused by the larvae were studied in maize fields over two successive seasons in northern Ghana. Pheromone traps were deployed in sole maize fields located in Northern (NR), Upper East (UER) and Upper West (UWR) regions to assess male moth population over time. Data on damage to maize by the larvae as well as climatic variables were also recorded. A total of 2601 FAW moths were captured over the two seasons from the three regions. In general, catches increased steadily from time of emergence (i.e., 12.2 ± 1.4 and 14.4 ± 2.6 moths in July 2017 and 2018, respectively) and peaked when the plants were growing into the reproductive stage (i.e., 13.9 ± 2.2 and 56.0 ± 14.9 moths in August 2017 and 2018, respectively); afterwards catches declined significantly. There were no significant differences between regions in both years for mean their moth catches. Damage to maize was significantly higher in 2017 (4.8 ± 0.4) than in 2018 (2.4 ± 0.3) (P = 0.005). This variable correlated positively with FAW larval abundance. Rainfall was the only climatic variable that influenced moth abundance significantly and positively in all three regions in both years; except for 2018 in UER. Thus, management of FAW in northern Ghana and locations with similar agro-ecologies must be from emergence to the tasselling stage, as well as periods of increased precipitation.

Maize (Zea mays L.), an important staple crop in West and Central Africa (WCA), has enormous potential to reduce food insecurity in this sub - region. r esearch 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 lat - est era of improvement, were identified as the highest yielding and most stable cultivars and should be promoted to contribute to food secu

Maize is one of the most important food crops in Ghana even though its production has not reached self sufficiency levels. Drought and striga infestation are among the most important production constraints of maize in Ghana. Promising high yielding, drought and striga tolerant maize varieties are being evaluated by CSIR and IITA in participatory on-farm trials and demonstrations. These varieties however need to meet farmers’ varietal preferences in order for them to adopt. This study therefore sought to assess farmers’ preference for the different drought tolerant maize varieties, and determine factors that influence their choices. Kendall’s coefficient of concordance was used to test the level of agreement between farmers on their preferences. The ordered logistic regression was used to estimate the determinants of farmer’s preference using cross-sectional observations from 120 maize farmers in the Transitional and Savannah zones of Ghana. Results indicate that maize varieties that are early maturing (2.38) and drought tolerant (2.45) were most preferred by farmers. Area under maize cultivation, fertilizer usage and family size are the factors that were found to influence farmers’ preference for improved maize varieties. These factors should therefore be considered in varietal promotion. Key words: Drought tolerant, farmers’ preferences, determinant, savannah and transition zones of Ghana, ordered logit.