Article Archive: Volume 5 Issue 1 2026

Genotypic Variation and Seed Morphological Determinants of Maize (Zea mays L.) Performance and Resistance to Bacterial Streak in a Naturally Infected Field

  • Bukola Ojo Adediran1
  • Oluwafemi Michael Adedire2
  • Olufemi Stephen Olaoye3

Introduction Maize (Zea mays L.) is one of the world’s most important cereal crops, serving as a primary source of food, feed, and industrial raw material. Maize (Zea mays) cultivation and exploration have been at their all-time high in Nigeria and indeed, all parts of the globe [2]. In many maize-growing regions, particularly in tropical and subtropical environments, productivity is constrained by a wide range of biotic stresses, among which bacterial diseases have gained increasing importance [19]. One of the emerging bacterial diseases affecting maize is Bacterial Leaf Streak (BLS), caused by Xanthomonas vasicola pv. vasculorum (Xvv) [14]. The disease is characterized by elongated, water-soaked lesions on leaves that coalesce to form streaks, leading to reduced photosynthetic area, premature senescence, and ultimately yield losses. In endemic areas, especially where climatic conditions favor disease development, bacterial streak has become a major challenge to sustainable maize production [20]. Chemical and cultural management strategies for bacterial streak are largely ineffective or uneconomical due to the limited availability of effective bactericides and the polycyclic nature of the pathogen [12]. Consequently, host-plant resistance remains the most viable and environmentally friendly approach for disease management [7]. However, the genetic basis of tolerance to bacterial streak in maize is complex, and resistance levels among available germplasm are variable [13]. Identifying and selecting genotypes that combine superior agronomic performance with tolerance to bacterial streak is therefore critical for breeding programs targeting disease-prone environments. Field evaluation of maize genotypes under natural disease pressure provides an opportunity to assess both yield performance and resistance stability under realistic agronomic conditions [9]. Such assessments help distinguish genotypes that can maintain acceptable productivity despite infection pressure, making them valuable candidates for further breeding and deployment in endemic regions [6]. Furthermore, understanding the interaction between the performance of released maize genotypes from research institutes like the Institute of Agricultural Research and Training (IAR&T) and disease intensity contributes to the development of selection indices that integrate yield potential, seed morphology, and disease tolerance [8]. The present study was therefore undertaken to evaluate the agronomic performance of eight (8) maize genotypes released by IAR&T, Ibadan, in a bacterial streak endemic field in order to identify promising genotypes and grain size that combine high yield potential with stable tolerance. Materials and Methods The experiment was conducted at the Teaching and Research Farm of Cocoa Research Institute of Nigeria (CRIN), Ibadan, Oyo State. Seeds of eight genotypes of maize used for the experiment were obtained at the seed store of IAR&T, Ibadan, Oyo State (Table 1). The experiment was carried out during the early cropping season of 2023 (May – August) on a bacterial streak endemic field [3]. Maize seeds (500 g) of each cultivar were sorted into three different sizes (big, medium, and small) [24][17]. One hundred seeds were randomly selected from each category to determine seed morphometrics through the use of a digital variety caliper (Table 2). The experiment was laid out in a randomized complete block design (RCBD), replicated three times. The experimental field was laid out in three blocks, and each block comprised three replicates. Inter-block spacing was 2.0 m, inter-row spacing was 0.75 m while intra-row spacing was 0.50 m and seeds were sown at 2 cm depth. Data were collected on five randomly selected plants to study the agronomic traits: Plant height at 95% maturity (cm), leaf area (cm2), stem girth (cm), cob length (cm), cob girth (cm), total grain weight (kg), cob weight/fruit (kg), grain yield per hectare (kg), harvest index (calculated as percentage of grain weight divided by total biomass), shelling percentage was calculated as percentage of grain weight divided by cob weight (%), 1000-seed was the average weight of 1000 seeds obtained from five shelled cobs (kg). The data collected were subjected to analysis of variance (ANOVA) using statistical analysis software [22]. Means were separated using Duncan’s multiple range test (DMRT) at 5% probability. Isolation of Xanthomonas vasicola and characterization of bacterial streak Affected portions (5 mm sections) of infected leaves were inoculated on Nutrient Agar for isolation of the streak pathogen (X. vasicola). Samples were surface-sterilised with 2% sodium hypochlorite, rinsed thrice with sterile water, drained, and inoculated on prepared agar plates [2]. Microbial strains were isolated from infected tissue samples on Nutrient Agar, and bacterial streak disease was eventually characterized in the maize genotypes as reported by Malvick et al., 2024 [15]. A modified disease severity scale (0-5) for maize streak was used Mushayi et al., 2025 [16], while percentage incidence [18] of the disease was determined as described below: Resistance and tolerance to bacterial wilt were determined according to the rating class described by Borisade et al., 2017 [5] as < 1% and ≤ 25% severity measures, respectively. Results and Discussion Performance of maize genotypes The mean performance of growth characters evaluated in the eight varieties of maize is presented in Table 3. There was no significant difference among the varieties in terms of their stem girth and seed sizes, although variety ART-98-SWI (Small) recorded the highest mean of 6.26 cm. There was no significant difference in the plant height of maize; however, plant height for small seed size was lower, considering seed size. This was in concordance with the result observed in a collection of soybean varieties [27]. Mean performance of yield and yield components evaluated in the eight (8) varieties of maize is presented in Table 4. With reference to cob length, there was no significant difference in the varieties and seed sizes. However, variety Suwan-1 (Large) recorded the longest cob length (28.20 cm) while ALT-98-SW6 (Small) recorded the least cob length (23.49 cm). For cob girth, there were significant differences among the varieties; variety ALT-98-SW6 (Large) recorded the widest average cob (17.83 cm), while the shortest cob girth was recorded for variety LNTP (Small). For 1000-seed weight, a significant difference was observed among the varieties and their seed sizes. Variety DMR-LSR-Y (Small) recorded the heaviest weight (0.38 kg). Variety LNTP (Medium) recorded the heaviest/largest total grain yield (0.23 kg). PRO-VIT-A (Medium) recorded … Read more

Climate Change Adaptation through Soil and Nutrient Management for Sustainable Crop Production in Bangladesh: A Review

  • Md. Jahangir Kabir1
  • Khalid Syfullah2

Introduction: Climate change poses a substantial threat to global agricultural systems, with developing countries experiencing disproportionate impacts due to their high dependence on climate-sensitive livelihoods and limited adaptive capacity [1,2]. Bangladesh is recognized as one of the most climate-vulnerable countries in the world, where agriculture plays a central role in food security, employment, and rural livelihoods[1]. Increasing temperatures, erratic rainfall patterns, frequent floods, prolonged droughts, and accelerating salinity intrusion are already disrupting crop production systems across the country [2]. These climate-induced stresses are projected to intensify in the coming decades, posing serious challenges to sustaining crop productivity and national food security[1]. Soil health and nutrient availability constitute the foundation of sustainable crop production, yet they are highly sensitive to climate variability and extreme events [3, 4]. Rising temperatures accelerate organic matter decomposition, alter nutrient mineralization rates, and increase nitrogen losses through volatilization and leaching [5, 3]. Changes in precipitation regimes influence soil moisture dynamics, erosion processes, and nutrient transport, while floods and waterlogging modify redox conditions, affecting the availability of nitrogen, phosphorus, sulfur, and micronutrients [6]. In coastal regions of Bangladesh, sea-level rise and saline water intrusion further exacerbate soil degradation by increasing salinity and sodicity, leading to nutrient imbalance and reduced crop growth [7,8]. Consequently, climate change is not only a direct stressor on crops but also an indirect driver of declining soil fertility and nutrient use efficiency [9]. Bangladesh agriculture is predominantly characterized by intensive cropping systems, particularly rice-based rotations, which place continuous pressure on soil resources [10]. Decades of high-input fertilizer use, often imbalanced and inefficient, combined with limited organic matter recycling, have resulted in declining soil organic carbon and emerging micronutrient deficiencies in many agroecological zones [11]. Under changing climatic conditions, these existing soil fertility constraints are becoming more pronounced, increasing the vulnerability of cropping systems to yield instability. Therefore, enhancing soil resilience and optimizing nutrient management are increasingly viewed as central pillars of climate change adaptation in agriculture [12,3]. Soil and nutrient management practices offer significant potential to buffer climate risks while supporting sustainable intensification [12,13]. Integrated soil fertility management, balanced and site-specific nutrient application, organic amendments, conservation agriculture, and climate-smart nutrient strategies can improve soil structure, water-holding capacity, nutrient retention, and crop nutrient uptake under variable climate conditions [14,9]. These practices not only enhance crop productivity and yield stability but also generate co-benefits such as soil carbon sequestration, reduced greenhouse gas emissions, and improved resource-use efficiency [15]. In the context of Bangladesh, where land availability is limited and production pressure is high, climate-adaptive soil and nutrient management approaches are particularly critical. Despite a growing body of research on climate change impacts and agricultural adaptation in Bangladesh, existing studies are often fragmented, focusing on individual crops, nutrients, or stress factors. A comprehensive synthesis that explicitly links climate change, soil processes, nutrient dynamics, and adaptation strategies for sustainable crop production remains limited [9]. Moreover, the integration of biophysical evidence with socio-economic and institutional considerations relevant to the adoption of improved soil and nutrient management practices has not been adequately addressed in previous reviews [16]. This review aims to critically synthesize existing knowledge on climate change adaptation through soil and nutrient management in Bangladesh agriculture. Specifically, it examines (i) climate-induced changes in soil properties and nutrient dynamics, (ii) soil and nutrient management strategies that enhance crop resilience and sustainability under climate stress, and (iii) key research gaps, policy implications, and future directions for strengthening climate-resilient crop production systems [1]. By consolidating current evidence, this review seeks to inform researchers, policymakers, and practitioners on pathways to sustainable agricultural adaptation in Bangladesh under a changing climate. 2. Climate Change Trends and Impacts on Bangladesh Agriculture 2.1 Observed and Projected Climate Trends in Bangladesh Bangladesh has experienced clear and consistent signals of climate change over recent decades, characterized by rising temperatures, altered rainfall patterns, and an increased frequency of extreme weather events [1,2]. Observational records indicate a gradual increase in both mean annual and seasonal temperatures, with more pronounced warming during the pre-monsoon and post-monsoon periods [17]. This warming trend has important implications for crop phenology, evapotranspiration demand, and soil biological activity [3]. Concurrently, rainfall patterns have become increasingly erratic, marked by intense short-duration rainfall events interspersed with prolonged dry spells, rather than uniform seasonal distribution [17,1]. Climate projections suggest that these trends will intensify in the future. Model-based scenarios indicate further increases in temperature, heightened rainfall variability, and greater incidence of extreme events such as floods, droughts, and heatwaves [1,2]. Sea-level rise is projected to exacerbate saline water intrusion in coastal and deltaic regions, while upstream hydrological changes are likely to influence river flooding dynamics in floodplain areas [8]. Together, these changes are expected to increase climate uncertainty for agricultural systems, placing additional stress on soils and nutrient cycling processes that underpin crop production [9]. 2.2 Impacts of Climate Variability on Soil Properties and Nutrient Dynamics Climate variability directly influences soil physical, chemical, and biological properties, thereby altering nutrient availability and use efficiency in agricultural systems [3,4]. Rising temperatures accelerate soil organic matter decomposition, leading to declines in soil organic carbon stocks, which are critical for nutrient retention, aggregation, and moisture regulation [5]. Enhanced decomposition rates can initially increase nutrient mineralization but often result in long-term nutrient depletion and reduced soil resilience under intensive cropping systems [9]. Altered rainfall regimes further affect nutrient dynamics by influencing soil moisture status, erosion, and leaching losses [18]. Intense rainfall events increase surface runoff and soil erosion, leading to the loss of nutrient-rich topsoil and associated macro- and micronutrients [19,20]. Conversely, prolonged dry periods restrict nutrient diffusion and microbial activity, limiting nutrient uptake by crops [21]. Flooding and waterlogging, common in low-lying areas of Bangladesh, create anaerobic soil conditions that modify redox-sensitive nutrient transformations, particularly nitrogen and sulfur, resulting in gaseous losses and reduced fertilizer efficiency [6]. In coastal regions, salinity intrusion driven by sea-level rise and storm surges disrupts soil nutrient balance by increasing sodium concentrations, reducing calcium and potassium availability, and impairing root nutrient uptake [7,8]. Climate-induced changes in soil … Read more