Suwilanji Nanyangwe

Fall armyworm, Spodoptera frugiperda (J.E. Smith), has emerged as one of the most damaging invasive pests affecting maize production and household food security across sub-Saharan Africa since its first detection in 2016. This systematic review synthesizes empirical evidence published between 2016 and 2025 to assess the agronomic, livelihood, and food security impacts of FAW on smallholder farming systems across Eastern, Southern, Western, and Central Africa. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and the Population, Intervention, Comparison, Outcome, Time, and Setting (PICOTS) framework, 20 studies (17 empirical and 3 contextual) were identified through comprehensive searches of academic databases and institutional repositories and were included in the final synthesis after methodological screening. The evidence indicates that FAW invasion causes substantial maize yield losses ranging from approximately 20% to 50%, with the greatest reductions reported in rain-fed systems with limited access to pest management technologies. Infestation rates frequently exceeded 50%, particularly during early invasion phases. Beyond agronomic losses, several studies reported reduced household income, constrained food availability, and livelihood disruptions, including increased labor requirements, higher production costs, and reliance on short-term coping strategies. Only a small proportion of studies (n = 4) directly assessed nutrition-related indicators, but the available evidence indicates declines in dietary diversity in severely affected communities. Overall, the agronomic impacts of FAW are consistently documented across regions, whereas the socioeconomic and nutrition outcomes remain comparatively underreported, indicating a significant evidence gap. These findings highlight FAW as both an agronomic and livelihood challenge, underscoring the need for integrated pest management strategies, strengthened extension services, and coordinated policy responses to safeguard food and income security among smallholder farmers in Africa.

Genetic diversity within maize inbred populations is essential for sustaining genetic gain in breeding programmes. This study evaluated 280 maize inbred lines with two checks using an augmented block design (22 × 14). At harvest, 271 lines and two checks were analysed, with nine entries excluded due to poor survival. Using both descriptive (24) and quantitative (19) traits, significant variations were observed across many traits. Descriptive traits varied among the genotypes, as revealed by graphical analysis and correlation heatmaps. The likelihood ratio test (LRT) for lines showed significant differences for several quantitative traits with moderate–high heritability, while anthesis–silking interval, tassel length, ear position, ear aspect, bad husk cover, number of plants, and number of ears per plant exhibited low heritability. High genetic advance as a percentage of the mean was observed for grain yield, plant height, grain texture, number of plants, number of kernels, and grain weight per plant. Positive associations were observed among genotypic coefficient of variation, genetic advance, and heritability. Grain yield showed significant positive correlations with yield-related traits and morphological traits, but negative correlations with flowering traits. The first 10 principal components explained 86.17% of total variation, with flowering traits contributing most to variability in PC 1. Cluster analysis grouped genotypes into 10 clusters, with substantial genetic divergence within and between cluster groups. In conclusion, the study revealed considerable genetic diversity, supporting the selection of superior parents in breeding programmes and developing improved maize varieties to enhance productivity.

Background/Objectives: Fall armyworm (FAW) (Spodoptera frugiperda) is a major constraint to maize production in Sub-Saharan Africa, including Mozambique. This study aimed to evaluate maize genotypes for resistance to FAW under greenhouse and field conditions and to assess the association between phenotypic resistance and genomic variation based on single nucleotide polymorphisms (SNPs). Methods: A total of 20 maize genotypes from the Agricultural Research Institute of Mozambique (IIAM) and the International Maize and Wheat Improvement Center (CIMMYT) were evaluated. FAW damage was quantified using the area under the damage progress curve (AUDPC). Phenotypic data were analyzed using ANOVA and mixed models, while molecular analysis was conducted using 10,603 SNP markers located on chromosomes previously associated with FAW resistance. Results: Significant genotypic differences were observed under greenhouse conditions (F = 1.94, p = 0.012) and in the field (p = 0.021), although environmental factors reduced variation in the field. Genotypes such as CML67, CML338, and Kenya amarelo (Acc3550) exhibited consistently lower AUDPC values across environments, indicating stable resistance. However, SNP allele proportion was not significantly associated with phenotypic resistance (r = 0.34, p = 0.147), and regression and ANOVA analyses confirmed the absence of a significant relationship (p > 0.05). Conclusions: FAW resistance in maize is quantitatively inherited and not explained by general genomic variation across candidate regions. Phenotypic screening remains essential, and further studies are required to identify specific loci for effective marker-assisted selection. The identified stable genotypes represent valuable resources for breeding FAW-resistant maize adapted to Mozambique.

Background/Objective: Maize (Zea mays L.) is a globally important cereal crop widely cultivated for food, feed, fodder, biofuel production, and various industrial applications. Maize landraces represent a valuable source of genetic diversity that supports adaptationand resilience across diverse agroecological environments. However, evidence on phenotypic diversity based on agro-morphological traits in these landraces remains fragmented across regions and varying analytical approaches. This review synthesized global evidence on phenotypic variation, heritability patterns, experimental designs, statistical methods, and the extent of integration between phenotypic and molecular data. Methods: A systematic literature search was conducted in GoogleScholar, ScienceDirect, PubMed and AGRIS for studies published between 2000 and 2025 evaluating phenotypic diversity in maize landraces. The review followed PRISMA 2020 guidelines, and f50 studies from 30 countries met the eligibility criteria. Results: Substantial and structured phenotypic diversity was consistently reported across studies, with flowering time, plant architecture, and ear and kernel traits emerging as major contributors to landrace differentiation. Traits with moderate to high heritability were mainly morphological and phenological, suggesting relative genetic control and potential suitability for phenotypic selection. In contrast, grain yield showed greater environmental sensitivity and variable heritability, reflecting complex inheritance and genotype × environment interactions. Although molecular markers were incorporated in a some studies, integrative analyses linking phenotypic and genetic data remained limited. Conclusions: Phenotypic evaluation remains a reliable approach for characterizing maize landrace diversity. However, standardized methodologies, greater integration with molecular data and cross-environment validation are needed to strengthen inference and utilization in breeding and conservation. The review also provides recommendations for improving agro-morphological assessment in maize landraces.

Background/Objectives: Downy mildew, caused by Peronosclerospora and Sclerophthora species, is a major constraint to maize production in tropical and subtropical regions, with yield losses of 30–100%. This systematic review synthesised evidence on methods used to screen maize for downy mildew resistance and assessed their effectiveness, reliability, and associated markers. Methods: PubMed, Google Scholar, ScienceDirect, and CAB Abstracts were searched (last searched 22 October 2025) for English-language studies (1990–2025) evaluating phenotypic or molecular screening methods. Risk of bias was assessed using the RoB 2 framework. Narrative synthesis was conducted following a protocol registered on the Open Science Framework. Results: Twelve studies met the inclusion criteria, predominantly from India and Cambodia. Spreader row systems (seven studies) and conidial spray inoculation (six studies) were the most common field methods, while the glasshouse sandwich technique generated the highest disease pressure. Cross-method correlations were strong (r = 0.92–0.99), and heritability estimates ranged from 0.50 to 0.97. QTL mapping identified resistance loci on chromosomes 2, 3, and 6, with chromosome 6 stable across multiple pathogen species. Evidence certainty was moderate for method effectiveness and low for molecular markers. Conclusions: Established phenotypic screening methods reliably discriminate resistant germplasm; however, standardised protocols, broader geographic validation, and independent molecular marker confirmation are needed.

Background/Objectives: Combining ability (CA) analysis is a key tool in maize breeding for developing superior hybrids by evaluating parental genetic potential through general combining ability (GCA) and specific combining ability (SCA). Despite its widespread use, knowledge of how CA techniques help overcome major constraints to maize production in sub-Saharan Africa (SSA) is limited. This review summarizes recent applications of CA analysis in addressing maize breeding challenges across SSA. Methods: A systematic literature search was conducted using ScienceDirect, Springer, and Google Scholar for studies published between 2020 and September 2025. Search terms included maize, combining ability, and SSA. The review followed PRISMA guidelines, and 94 studies met the eligibility criteria and were included in the analysis. Results: Most studies were conducted in Nigeria (42%), Ethiopia (16%), and Ghana (14%), indicating regional concentration of maize hybridization research within SSA. Yield improvement was the dominant breeding objective across the region. Inbred lines with high GCA were predominantly used as parental materials compared with open-pollinated varieties. The line × tester mating design was the most frequently applied, followed by other mating designs. Across 580 environments, GCA contributed 80%, SCA 19%, and combined GCA/SCA 1% to hybrid performance. The predominance of GCA across traits and environments underscores high additive gene effects, largely due to the high homozygosity of inbred line parents. Conclusions: It has been observed in this systematic review that combining ability analysis remains essential for enhancing maize productivity and resilience in SSA by enabling identification of superior parents, efficient mating designs, and development of widely adapted hybrids.