Yield gains and associated changes in an early yellow bi-parental maize population following genomic selection for Striga resistance and drought tolerance.

BACKGROUND: Maize yield potential is rarely maximized in sub-Saharan Africa (SSA) due to the devastating effects of drought stress and Striga hermonthica parasitism. This study was conducted to determine the gains in grain yield and associated changes in an early-maturing yellow bi-parental maize population (TZEI 17 x TZEI 11) F3 following genomic selection (GS) for improved grain yield, Striga resistance and drought tolerance. Fifty S1 lines were extracted from each of cycles C0, C1, C2 and C3 of the population and crossed to a tester TZEI 23 to generate 200 testcrosses. The testcrosses were evaluated under drought, artificial Striga-infested and optimal (free from Striga infestation and without limitation of water and nitrogen) environments in Nigeria, 2014-2017. RESULTS: Gains in grain yield of 498 kg ha- 1 cycle- 1 (16.9% cycle- 1) and 522 kg ha- 1 cycle- 1 (12.6% cycle- 1) were obtained under Striga-infested and optimal environments, respectively. The yield gain under Striga-infested environments was associated with increased plant and ear heights as well as improvement in root lodging resistance, husk cover, ear aspect and Striga tolerance. Under optimal environments, yield gain was accompanied by increase in plant and ear heights along with improvement of husk cover and ear rot resistance. In contrast, genomic selection did not improve grain yield under drought but resulted in delayed flowering, poor pollen-silk synchrony during flowering and increased ear height. Genetic variances and heritabilities for most measured traits were not significant for the selection cycles under the research environments. Ear aspect was a major contributor to grain yield under all research environments and could serve as an indirect selection criterion for simultaneous improvement of grain yield under drought, Striga and optimal environments. CONCLUSION: This study demonstrated that genomic selection was effective for yield improvement in the bi-parental maize population under Striga-infested environments and resulted in concomitant yield gains under optimal environments. However, due to low genetic variability of most traits in the population, progress from further genomic selection could only be guaranteed if new sources of genes for Striga resistance and drought tolerance are introgressed into the population.

Genetic studies of extra-early provitamin-A maize inbred lines and their hybrids in multiple environments.

Vitamin A deficiency, drought, low soil nitrogen (low-N), and Striga hermonthica parasitism of maize (Zea mays L.) cause malnutrition and food insecurity in sub-Saharan Africa. The objectives of this study were to determine combining abilities of extra-early provitamin A (PVA) lines, classify them into heterotic groups (HGs), identify testers, and determine yield stability of hybrids under contrasting environments in two trials. In Trial 1, 190 F1 hybrids plus six checks were tested under Striga-infested, drought, and stress-free environments in Nigeria from 2015-2017. In Trial 2, 35 extra-early yellow hybrids were evaluated under low-N, Striga-infested, and stress-free environments in 2018. TZEEIOR 202 and TZEEIOR 205 had PVA concentrations of 23.98 and 22.56 µg g-1. TZEEIOR 197 × TZEEIOR 205 (20.1 µg g-1) and TZEEIOR 202 × TZEEIOR 205 (22.7 µg g-1) contained about double the PVA level of the commercial check, TZEEI 58 × TZEE-Y Pop STR C5 (11.4 µg g-1). Both general (GCA) and specific (SCA) combining ability variances were significant for most agronomic traits, although GCA was larger than SCA effects, indicating GCA effects primarily controlled the inheritance of those traits. TZEEIOR 97 and TZEEIOR 197 were identified as inbred testers. TZEEIOR 197 × TZEEIOR 205 was identified as a single-cross tester and the most stable and highest-yielding hybrid across environments. TZEEIOR 202 and TZEEIOR 205 should be invaluable resources for breeding for high PVA. Provitamin A level was independent of hybrid yield potential, indicating that selection of superior hybrids with elevated PVA levels should be feasible.

Genetic Variances and Heritabilities of Traits of an Early Yellow Maize Population after Cycles of Improvement for Striga Resistance and Drought Tolerance.

Drought and Striga are principal constraints to maize (Zea mays L.) production in sub-Saharan Africa. An early yellow maize population, TZE-Y Pop DT STR, which had undergone five cycles of selection for resistance to Striga, followed by three cycles of improvement for drought tolerance, was investigated for yield gains, changes in genetic variance, and interrelationships among traits under drought stress and optimum environments. Two hundred and forty S1 lines comprising 60 each from the base population and subsequent populations from three selection cycles improved for grain yield and drought tolerance were assessed under drought and optimal environments in Nigeria from 2010 to 2012. Genetic improvements in grain yield of 423 and 518 kg ha-1 cycle-1 were achieved under drought stress and optimal environments. Predicted improvements in selection for yield were 348 and 377 kg ha-1 cycle-1 under drought stress and optimum environments, respectively. The highest yield observed in C3 was accompanied by reduced days to silking and anthesis-silking interval, improved plant aspect and ear aspect, and increased plant height and ears per plant across research environments, as well as improved stay-green characteristic under drought. The level of genetic variability for yield and a few other traits were maintained under drought and optimal environments in the population. The presence of residual genetic variability for yield and other assayed traits in C3 indicated that progress could be made from future selection in the population depending on the ability of breeders to identify outstanding genotypes and the precision level of experimentation. Substantial improvement has been made in yield and drought tolerance in C3 of the population.

Gains in Grain Yield of Extra-Early Maize during Three Breeding Periods under Drought and Rainfed Conditions.

Drought is a key maize (Zea mays L.) production constraint in sub-Saharan Africa. Fourteen, fifteen, and twenty-five extra-early maturing maize cultivars, with varying Striga resistance and drought and low soil N tolerance, were developed from 1995 to 2000 (Period 1), 2001 to 2006 (Period 2), and 2007 to 2012 (Period 3), respectively. The objectives of this study were to examine yield gains in the cultivars and to investigate inter-trait relationships and yield stability under six drought and 17 rainfed conditions in West Africa from 2013 to 2016. Annual rate of yield increase across cultivars was 0.034 (3.28%) and 0.068 Mg ha-1 (2.25%), whereas yield gains per period were 0.17 and 0.38 Mg ha-1 under drought and rainfed environments, respectively. Yield gains under drought and rainfed environments were related to prolonged flowering period, increased plant and ear heights, improved stalk lodging, and ear and plant aspects, whereas delayed leaf senescence and increased number of ears per plant accompanied yield improvement under drought only. Ear aspect and number of ears per plant were primary contributors to yield and could be used as selection criteria for yield enhancement under drought and rainfed conditions. High-yielding and stable cultivars across all environments based on additive main effects and multiplicative interaction (AMMI) biplot included '2004 TZEE-Y Pop STR C4' and 'TZEE-W Pop STR BC2 C0' of Period 2 and '2009 TZEE-W STR', 'TZEE-Y STR 106', 'TZEE-W STR 107', and 'TZEE-W DT C0 STR C5' of Period 3. These cultivars could be commercialized to improve food self-sufficiency in sub-Saharan Africa.

Typhoid fever associated with severe hepatitis.

While typhoid is quite common in our environment, presentation in association with severe hepatitis and hepatic encephalopathy is uncommon. The case of a 14 year old male with typhoid who presented with jaundice and severe hepatitis with encephalopathy is presented. The first symptoms occurred one week before presentation. The clinical features and laboratory investigations confirmed typhoid fever. The associated severe hepatitis could have been related to a direct liver involvement by Salmonella typhi, drug toxicity or hepatitis B infection from previous indiscriminate parenteral drugs. The specific cause of the hepatitis could not be confirmed. The patient is presented to illustrate a rare association and possible complication of typhoid fever, inappropriate self and other medication in the place of proper hospital presentation and assessment and the diagnostic difficulties confronting many centres in the developing environment.

A review of the management of perforated duodenal ulcers at a tertiary hospital in south western Nigeria.

BACKGROUND: Gastro-duodenal perforations are common and may complicate peptic ulcer disease. Management is often by surgical closure. OBJECTIVE: To determine the patterns of presentation and mode of management of duodenal ulcer perforations. METHODS: Retrospective review of patients with duodenal ulcer perforations seen at the Obafemi Awolowo University Teaching Hospital between June 2001 and July 2011. Patients' records were reviewed for demography, duration of disease, probable risk factors, type of surgery and complications. Data obtained was analyzed using SPSS 15.0. RESULT: Forty- five patients were reviewed. There were 37 males (82.2%). Mean age was 39.7years (range 15-78years). There were 10 (22.6%) students and 8(17.8%) farmers. NSAIDs abuse (11), previous peptic ulcer disease (2), and no prior dyspeptic symptoms (20) constituted 24.4%, 4.4% and 44.4% respectively of cases. Seven (16%) patients presented less than 24 hours of onset of illness. Forty one perforations (91.1%) involved the first part of duodenum. Twenty two (49%) patients had Graham's omental patch. We had one (2.2%) failed repair and six (13.3%) mortalities. CONCLUSION: Late presentation of duodenal ulcer perforation is common with high mortality. Pragmatic surgical intervention with Graham's omentopexy with broad spectrum antibiotics is still commonly practiced.

Pentalogy of cantrell: a report of three cases.

Pentalogy of Cantrell is a rare upper midline syndrome that may present in association with anomalies outside the torso. The pentad - the supraumbilical body wall defect, sternal defect, deficiency of the anterior diaphragm, defect of the diaphragmatic pericardium, and the intracardiac anomalies - was first described by Cantrell et al., in 1958. The defect is said to be more common in males, and survival is dependent on the cardiac malformations and on the degree of completeness of the syndrome. We report three cases of Cantrell's pentalogy managed in our unit. Two of the patients were females and one a male. All were seen at peripheral health centers before being referred to us. Age at presentation for the girls was 18 hours and 36 hours, respectively, the boy presented at the age of six weeks. All of their parents were unschooled manual workers. All patients presented with a defect in the supraumbilical body wall, bifid sternum, and a visible cardiac impulse. We were unable to do echocardiography to rule out intracardiac anomalies in the three patients. The thin membranous covering of the epigastrium in the female patients was managed conservatively. Both female patients were discharged against medical advice as requested by their parents, due to financial constraints. The male patient was lost to follow up after two clinic visits. A multidisciplinary approach to the management of this syndrome is recommended.

Experience with transverse preputial island flap for repair of hypospadias in Ile-Ife, Nigeria.

OBJECTIVE: To review our experience with the use of transverse preputial island flap in the repair of hypospadias in the paediatric surgical unit of our University Teaching Hospital, Nigeria. PATIENTS AND METHODS: We reviewed the cases of hypospadias managed by transverse preputial island flap repair over a ten year period (1996 and 2006) in the paediatric surgical unit of our institution. Data was retrieved from the case notes and analysed. RESULTS: Fifty-one patients had hypospadias repair during the period, 22 of whom were by transverse preputial island flap repair. Hypospadisas were in penile shaft in 16 (72.7%), penoscrotal in 5 (22.7%) and perineal in 1 (4.55%). All the patients had intact prepuce at presentation and chordee was present in 18 (81.8%). The commonest complication was urethrocutaneous fistula in five patients, which closed spontaneously in three leaving 2 patients (9.1%) with persistent urethrocutaneous fistular. CONCLUSION: Transverse preputial island flap urethroplasty remains a viable option in the management of hypospadias especially when the meatal opening is proximal, with associated chordee limiting the options in the repair.