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Maize is one of the most planted crops in Nigeria and it accounts for the largest share of the country's coarse grain production. Maize farming is carried out in nearly all the geographical zones in Nigeria. However, the bulk of the country's maize production is concentrated in Kaduna, Katsina, Niger, Plateau, Taraba, Kano and Oyo. These maize producing states accounts for nearly two-third (64%) of maize produced in Nigeria. Current maize yield averages 1.7 t/ha and is barely sufficient for the region's requirements due to drought, striga infestation and low N stresses. The objective of this study was to compare new stress tolerant maize hybrids and open pollinated varieties (OPVs) against the best released commercial varieties in Nigeria using farmer participatory approach and to validate on-station results. Maize varieties were simultaneously selected on-station from the different agro-ecology in Nigeria during the 2019/2020 and 2020/2021 seasons. During the season, 12 promising stress tolerant maize hybrids and OPVs among which are extra-early, early and intermediate were selected from the on-station based on their mean grain yield and stability. These selected varieties were compared with the best commercial check varieties on-farm across locations in Nigeria in a randomized complete block design. The genotype + genotype x environment comparison biplot showed hybrid AS1909-5, EWTH-14 together with other new stress tolerant hybrids and OPVs to be stable and high yielding on-station across locations compared to the commonly grown checks. This indicated that hybrid AS1909-5 and EWTH-14 possesses beneficial alleles that contributed to the observed superior performance when compared to the other hybrids. The new stress tolerant hybrids showed a yield advantage over the commercial check varieties both in the extra-early, early and the intermediate maturing categories, and the gains were bigger under stress conditions. Under farmers' fields, DT STR Syn/TZL Comp.-W, 2015 DTE STR-Y Syn, AS1909-5, AS2001-16, EWTH-14 and EEPVAH-95 were high yielding and stable across locations and recommended for release. [ABSTRACT FROM AUTHOR]

Drought tolerant maize (Zea mays L.) hybrids are crucial for the sustainability of maize production in the drought-prone areas of Sub-saharan Africa. Understanding the genetics of inheritance under drought is important in designing breeding strategies for improving grain yield and other agronomic traits under drought. Two studies were conducted to determine the the genetic variability and mode of gene action for grain yield and other traits of different maturity groups of maize inbreds for tolerance to drought and identify the promising drought-tolerant maize hybrid(s) for drought-prone regions. Eleven inbred lines of different maturity groups and endosperm-modification were crossed using diallel mating scheme to generate 55 F1 hybrids. The 55 hybrids along with one check and 11 inbreds were separately evaluated under induced drought and optimum growing conditions at Samaru and Kadawa. The experiments were laid in a 7 x 8 alpha lattice design and replicated two times using single-row plot of 4-m long. Row and hill spacing were 0.75 m and 0.4 m respectively. General combining ability (GCA) and Specific combining ability (SCA) mean squares were significant (p < 0.01) for grain yield and most other traits under drought and optimum growing conditions. SCA accounted for 79.3% and 64.2% of the total genetic variation for grain yield under drought and optimum growing conditions, indicating that non-additive gene action largely controlled the inheritance of grain yield of the hybrids. Hybrid TZEE-W-Pop STR C5 x TZEI 87 should be further tested in multiple environments for adoption by farmers in drought prone areas of Sub-saharan Africa. [ABSTRACT FROM AUTHOR]

The menace of low soil nitrogen poses a significant challenge to maize production in sub-Saharan Africa, necessitating the development of high-yielding hybrids with increased nitrogen (N) tolerance. Two hundred and forty (240) maize hybrids were evaluated across eight environments at Zaria and Mokwa in Nigeria during the 2020 and 2021 growing seasons, encompassing both low- and optimum-N conditions. The primary objective of the study was to identify high-yielding, stable, and low-N-tolerant hybrids for potential adoption in Nigeria. The study results underscored the significant impact of nitrogen availability on various agronomic traits, causing a substantial 53% reduction in grain yield. Significant genetic variation was observed among hybrids for most measured traits. SMLW146 × IITA1878, SMLW147 × SAM50M and SMLW147 × IITA1878 were the highest-yielding hybrids across the test environments with a yield advantage of 48.2%, 46.6% and 43.1%, respectively over the best check. GGE biplot analysis identified Mokwa Low-N 2021 (MLN21) and Mokwa optimum-N 2021 (MOP21) as discriminating and representative environments for selecting superior hybrids. SMLW147 × SAM50M emerged as the most stable low-N tolerant hybrid with the highest yield performance. Conversely, hybrid SMLW147 × IITA1878 produced a high yield across environments but was unstable. The study concludes by recommending SMLW147 × SAM50M for cultivation across both low- and optimum-N conditions, while SMLW147 × IITA1878 is specifically recommended for cultivation in optimum-N environments. Anthesis-silking interval, plant aspect, ear aspect, and ear height were identified as the most suitable secondary traits for selecting hybrids for high grain yield under low-N conditions.

Identification of ideal testing sites for selection of superior maize (Zea mays L.) germplam is vital to the success of a maize breeding programme. Sixteen provitamin A maize genotypes were evaluated at seven locations in savanna agro-ecologies of Nigeria for 3 yr to assess the representativeness, discriminating ability, and repeatability of the testing sites and to identify ideal testing sites for selection of superior maize germplasm. Location, year, and their interaction effects were significant for grain yield and most measured traits while genotype and genotype' year interactive effects were significant for grain yield. The genotype main effects plus genotype' environment interaction (GGE) biplot analysis revealed PVA SYN-18 F2 as the highest-yielding and most stable genotype across environments. The GGE biplot identified Zaria, Saminaka, and Kaboji as the most discriminating locations. Also, the biplot identified Kaboji, Batsari, Saminaka, and Zaria as the most repeatable locations. Zaria and Saminaka, being among the most discriminating, representative and repeatable locations, were considered as the core testing sites for selection of superior maize genotypes for release and commercialization. The core testing sites identified in this study should facilitate the identification of stable and high-yielding maize germplasm adaptable to the savannas agro-ecologies of Nigeria. [ABSTRACT FROM AUTHOR]

Animal African Trypanosomosis (AAT) is a devastating protozoan disease of animals and humans caused by Trypanosoma spp resulting in a great economic loss in the livestock industries, in the sub-sahara Africa. Cardiac troponin I is released from myocytes in both reversible and irreversible myocardial injuries. This study investigated the expression of cardiac troponin I (cTn I) in dogs experimentally infected with Trypanosoma congolense. Fifteen mongrel dogs of both sexes and with average body weights of 9.3 kg were divided into three groups (A, B and C). Dogs in group A were uninfected, group B were infected but untreated, while group C were infected and treated with Diminazene aceturate at a single dose of 3.5 mg/kg intramuscularly. The serum cTn I concentrations in infected dogs were elevated on days 1, 10 and 17 post-infection (pi). Serum cTn I concentrations in dogs that were infected and treated decreased on day 5 post-treatment (day 22 pi) compared to those that were infected but not treated. Post mortem and histopathological findings in the heart of a dogs that died of the disease in the infected but not treated group revealed no visible lesions. We concluded that the elevation of cTn I in Mongrel breed of dogs can occur without structural damage to cardiac muscles. [ABSTRACT FROM AUTHOR]

Maize is a strategic food crop in sub-Saharan Africa. However, most maize growing tropical savannas particularly in West and Central African experience the occurrence of frequent droughts and Striga infestation, resulting in 30–100% yield losses. This production zones need maize cultivars that combine tolerance to the two stresses. IITA in collaboration with national partners has thus employed a sequential selection scheme to incorporate both drought tolerance and Striga resistance in topical maize hybrids using reliable screening protocols. The main objective of the present study was therefore to use grain yield and other agronomic traits recorded in regional collaborative hybrid trials conducted for 8 years under manged stressful and non-stressful conditions and across rainfed field environments to estimate genetic gains in grain yields using mixed model analyses. The results showed significant (p < 0.05) annual yield gains of 11.89 kg ha−1 under manged drought stress (MDS) and 86.60 kg ha−1 under Striga infestation (STRIN) with concomitant yield increases of 62.65 kg ha−1 under full irrigation (WW), 102.44 kg ha−1 under Striga non-infested (STRNO) conditions and 53.11 kg ha−1 across rainfed field environments. Grain yield displayed significant but not strong genetic correlation of 0.41 ± 0.07 between MDS and STRIN, indicating that gene expression was not consistent across the two stress conditions. Furthermore, grain yield recorded in MET had significant moderate genetic correlations of 0.58 ± 0.06 and 0.44 ± 0.07It with MDS and STRIN, respectively. These results emphasize the need to screen inbred linens under both stress conditions to further enhance the rate of genetic gain in grain yield in hybrids for areas where the two stresses co-occur. Nonetheless, this study demonstrated that the sequential selection scheme has been successful in generating hybrids with dependable yields that can reduce chronic food deficits in rural communities experiencing simultaneous presence of drought and S. hermonthica infestation in their production fields.

Drought is a major constraint to maize production in West and Central Africa (WCA). Assessment of genetic gain from S1 recurrent selection under drought is crucial for the development of drought tolerance breeding strategies. In an early white population, 60 S1 families each derived from the base population and three cycles of selection were evaluated under drought and well-watered conditions at two locations in Nigeria for 2 years to determine genetic variability, gains from selection and predict response to selection for grain yield and other traits. Genetic variances generally decreased for yield and other traits in advanced cycles under drought and well-watered conditions except yield and ear height under well-watered conditions. Similarly, heritabilities for yield and other traits decreased in advanced cycles under drought but increased in advanced cycles under well-watered conditions. Realized gain for yield was 0·291 t/ha, corresponding to 30·5% per cycle under drought and 0·352 kg/ha with a corresponding gain of 16·7% per cycle under well-watered conditions. Predicted gain based on C3 was 0·282 and 0·583 t/ha under drought and well-watered conditions. Low genetic variances, heritabilities and predicted gain for yield and other traits suggested a need to introgress drought tolerance genes into the population. [ABSTRACT FROM PUBLISHER]

Breeding for resistance to Striga hermonthica Del. (Benth) and tolerance to drought has been a major strategy to improve maize (Zea mays L.) production and productivity in West and Central Africa during the last three decades. The three decades consisted of three breeding periods or eras based on the germplasm and methodologies used; that is, 1988–2000, 2001–06 and 2007–11. A total of 50 early maturing cultivars, combining Striga resistance with drought tolerance were developed, including 15, 16 and 19 cultivars for the three periods, respectively. Although the cultivars were not selected intentionally for low-nitrogen (N) tolerance, it was hypothesized that tolerance to low-N had been significantly improved while selecting for drought tolerance and Striga resistance. This hypothesis was tested by evaluating the 50 cultivars in 2010 and 2011 in Nigeria at Mokwa and Ile-Ife under both low-N (30 kg N/ha) and high-N (90 kg N/ha) levels. Under low-N conditions, grain yield improved from 2280 kg/ha during the first period to 2610 kg/ha during the third period, an increase of 165 kg/ha per period with r2 of 0·99. Under high-N, yield increased from 3200 to 3650 kg/ha, an increase of 225 kg/ha and r2 of 0·93. Relative gain per period was 30 kg/ha for the two N rates with r2 values of 0·99 and 0·94 respectively. Grain yield performance of the 50 cultivars under low-N conditions adequately predicted their performance under high-N. Selection for Striga resistance and drought tolerance in early maturing maize populations enhanced low-N tolerance in the maize cultivars derived from the populations. The improvement was higher in later than earlier breeding periods. [ABSTRACT FROM PUBLISHER]