Influence of Sowing Date and Cultivar on Growth and Yield Performance of Wheat (Triticum Aestivum L.) in the Sahel Savanna, Nigeria

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Abdulrahman, A.B.¹ , Rabiu, R.T.¹ , Abdullahi, A.T.¹ , Samaila, A.¹ , Shittu, E.A²

¹Flour Milling Association of Nigeria (FMAN) Research Farm, Ringim, Jigawa State, Nigeria

²Department of Agronomy, Bayero University Kano, P.M.B 3011, Kano State, Nigeria

Corresponding Author Email: seabraham.agr@buk.edu.ng

DOI : https://doi.org/10.51470/AGRI.2025.4.3.39

Abstract

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1.0 INTRODUCTION

Wheat (Triticum aestivum L.) is one of the most important cereal crops globally, providing nearly 20% of the calories and protein consumed by humans and ranking second only to maize in total production, with more than 770 million tonnes harvested annually [19]. Wheat is utilised in diverse forms, including bread, pasta, noodles, biscuits, and starch, while its milling by-products, such as bran and middlings, serve as valuable livestock feed ingredients. This dual role in food and feed systems underscores wheat’s contribution to global food and nutrition security [6][19]. Its adaptability to a wide range of environments has further established the crop as a central component of agricultural systems worldwide.

Despite its global prominence, wheat production in Sub-Saharan Africa remains low. Nigeria is among the largest wheat importers on the continent, with local production meeting less than 10% of annual demand. This widening supply gap is driven by rapid population growth, urbanisation, and dietary shifts, which continue to increase demand for wheat-based foods [36][32]. Domestic wheat cultivation is concentrated in the northern states, particularly in the Sahel Savanna zone, where ecological conditions permit seasonal production. However, yields in this region remain significantly below global averages due to poor agronomic practices, limited availability of improved cultivars, and environmental stressors.

A major emerging constraint to wheat production in Nigeria’s Sahel Savanna is climate change. Rising temperatures, recurrent droughts, and increasing rainfall variability have already begun to undermine wheat productivity across semi-arid regions [38][7]. Heat stress, particularly during anthesis and grain filling stages, shortens growth duration, reduces grain weight, and limits yield potential. Projections suggest that without adaptive strategies, climate change could substantially reduce wheat yields in Sub-Saharan Africa [38]. The Sahel Savanna, characterised by high evapotranspiration and water scarcity, is especially vulnerable to these climatic risks.

Nigeria faces an urgent wheat production challenge, with domestic output falling short of national demand and heavy reliance on imports straining foreign exchange reserves. In the Sahel Savanna, where wheat cultivation is concentrated, productivity remains low due to suboptimal agronomic practices, inappropriate sowing times, and poor cultivar adaptation. Sowing too early or too late exposes wheat to terminal heat and moisture stress, while cultivars lacking adaptability to local agro-ecologies perform poorly under climatic extremes [17][31]. These challenges are further intensified by climate change, which has increased temperature extremes, rainfall irregularities, and drought frequencies in the region [38]. Optimising sowing windows and deploying climate-resilient cultivars therefore represent practical, low-cost strategies with the potential to stabilise yields and strengthen the competitiveness of wheat production in the Sahel. Without clear scientific evidence on the most suitable sowing dates and variety choices, however, Nigeria risks continued reliance on imports and growing vulnerability to food insecurity.

This study is justified by the critical need to increase wheat productivity in Nigeria through evidence-based agronomic interventions. Optimising sowing dates and selecting well-adapted, heat-tolerant cultivars represent practical, cost-effective solutions to mitigate the negative impacts of climate variability on wheat production. Previous research in similar agro-ecologies has demonstrated that appropriate adjustment of sowing time and cultivar choice significantly improves yield stability under stress conditions [14][30]. By providing context-specific recommendations, this study will not only empower farmers in the Sahel Savanna to enhance productivity and resilience but also contribute to Nigeria’s broader goal of reducing wheat import dependency and strengthening food security. The study was conceived with the aim of assessing the influence of different sowing dates on the growth performance, phenological development, yield, and yield components of selected wheat cultivars under Sahel Savanna conditions.

2.0 MATERIALS AND METHODS

2.1 Experimental Site

The field experiment was conducted at the Flour Milling Association of Nigeria Research Farm, Ringim Local Government Area, Jigawa State, Nigeria. The site lies within the Sahel Savanna agro-ecological zone, which is characterised by a semi-arid climate with distinct wet and dry seasons. The study was carried out over two consecutive cropping seasons: 2021-2022 and 2022-2023.

2.2 Soil Characteristics

Before sowing each season, composite soil samples were collected from the experimental plots at a depth of 0-30 cm. The samples were analysed for key physical and chemical properties, including soil texture, pH, organic carbon, total nitrogen, available phosphorus, and exchangeable potassium. These analyses provided a baseline for nutrient management and interpretation of crop performance.

2.3 Treatments and Experimental Design

The experiment was arranged as a 2 × 6 factorial in a Randomised Complete Block Design (RCBD) with three replications to account for field variability. Treatments included two wheat cultivars (Norman and Borlaug) and six sowing dates (October 25, November 5, November 15, December 1, December 15, and January 1). Each treatment combination was assigned to a plot measuring 5 m × 3 m, giving a total of 36 experimental units.

2.4 Crop Management

Land Preparation and Sowing

Experimental plots were thoroughly prepared by ploughing and harrowing to create a fine, uniform seedbed, ensuring good seed-to-soil contact for optimal seedling emergence. Wheat seeds were sown using a single-row hand drill at a rate of 100 kg/ha, with uniform planting depth and spacing maintained across plots.

2.5 Fertilizer Application

Nutrient management was based on soil test results and local recommendations for irrigated wheat in the Sahel. Fertilizer was applied at a rate of 120 kg N, 40 kg P₂O₅, and 40 kg K₂O per hectare. At sowing, NPK (15:15:15) was applied as basal to supply 60 kg N, 40 kg P₂O₅, and 40 kg K₂O. The remaining 60 kg N was top-dressed at the tillering stage using urea.

2.6 Irrigation

Because of the arid environment, supplementary irrigation was essential. Furrow irrigation was used to maintain adequate soil moisture throughout the season. Irrigation scheduling was guided by tensiometer readings and crop water requirements, with particular attention to critical growth stages such as tillering, anthesis, and grain filling.

2.7 Weed Control

Weeds were managed through an integrated approach combining chemical and manual methods. Pendimethalin (1.0 kg a.i.ha^-1) was applied one day after sowing as a pre-emergence herbicide. Manual weeding was carried out 40 days after sowing to control late-emerging weeds.

2.8 Pest and Disease Management

Regular field scouting was conducted to monitor insect pests and diseases. When pest or disease incidence reached economic thresholds, appropriate control measures were promptly applied.

2.10 Harvesting

Wheat was manually harvested at physiological maturity, indicated by the yellowing of the flag leaf and peduncle, and grain hardening. Harvesting was performed uniformly across all plots to minimise variability.

2.11 Data Collection and Measurements

Throughout the experiment, data on agronomic and physiological parameters were collected following standard procedures. Phenological data included plant establishment, days to 50% heading, days to 50% flowering, and plant height. Yield components recorded were the number of spikes per square meter, number of grains per spike, spike length, and grain yield (kg/ha).

2.12 Statistical Analysis

All data were subjected to Analysis of Variance (ANOVA) using GenStat (17th edition). Where significant differences were detected (P < 0.05), treatment means were separated using the Student-Newman-Keuls (SNK) test.

3.0 RESULTS AND DISCUSSION

3.1 Soil characteristics

The soils at the experimental site across both seasons (2021/2022 and 2022/2023) were dominated by sand particles (61-63%), followed by silt (24-26%) and clay (13-14%). This classifies them as loamy sand, a texture typical of Sahelian soils (Table 1). Loamy sand soils are generally well-drained but have low water and nutrient retention, making them vulnerable to drought stress and nutrient leaching, which directly affects wheat productivity [9]. The pH in water (6.47-6.67) suggests slightly acidic soils, which are generally suitable for wheat growth. However, the much lower pH in CaCl₂ (4.15-4.22) indicates a tendency toward acidity in the soil’s exchange complex, which could reduce nutrient availability, especially phosphorus and micronutrients [34] (Schut and Giller, 2020).

Soil organic carbon (8.70-9.51 g kg^-1) was relatively low, reflecting limited organic matter content. This aligns with the widespread issue of declining soil organic matter in Sahelian agroecosystems due to continuous cultivation and limited organic inputs [27]. Low organic carbon is directly linked to reduced soil fertility, poor structure, and low microbial activity.

Similarly, total nitrogen (1.10-1.15 g kg^-1) and available phosphorus (5.94-6.08 mg g^-1) were very low, confirming that the soils are nitrogen- and phosphorus-deficient. These deficiencies are well-documented as the major yield-limiting factors for cereals, including wheat, in semi-arid regions [11]. Exchangeable bases showed moderate calcium (2.76-3.61 c mol kg^-1) and magnesium (1.06-1.13 c mol kg^-1) but low potassium (0.10-0.11 c mol kg^-1). The cation exchange capacity (CEC) of 5.50-5.90 c mol kg^-1 was also low, reflecting weak nutrient-holding capacity typical of coarse-textured soils [9].

Table 2 shows establishment percentage, Days to 50% flowering, Days to 50% heading and Days to maturity of wheat as influenced by sowing date, variety and season during 2022/2023 dry season. Results shows that sowing date significantly influenced establishment percentage, flowering, and heading, but not maturity. The highest establishment percentage was recorded with wheat sown on December 1st (153.4%), while the lowest was with January 1st sowing (126.2%). This indicates that delaying sowing into January exposes wheat to suboptimal germination conditions, likely due to higher soil temperatures and reduced moisture availability [18]. Similar findings have been reported in the Sahel and semi-arid regions, where delayed planting reduces stand establishment and subsequent yield potential [29].

For phenological traits, wheat sown on December 15th recorded the longest duration to flowering (68.92 days), while January 1st sowing flowered significantly earlier (62.75 days). This reduction in duration under late sowing reflects the heat stress-induced acceleration of phenological development, as crops adjust to complete their life cycle before terminal drought and high temperatures [21]. Heading followed a similar pattern, with significantly shorter durations in late sowing (57.25 days in January) compared to early November sowings (61-62 days).

Days to maturity were not significantly (P > 0.05) affected by sowing date, suggesting that while flowering and heading respond strongly to thermal regimes, final crop duration may be buffered by varietal adaptation and management practices. However, the trend showed slightly longer maturity in October sowing (114.5 days) compared to January sowing (110.1 days), consistent with the thermal time accumulation theory [16].

Variety had a significant (P <0.001) effect on all phenological traits. Norman exhibited longer duration to 50% flowering (71.92 days), 50% heading (65.56 days), and maturity (119.67 days) compared to Borlaug (61.64, 54.92, and 104.42 days, respectively). These results suggest that Norman is a late-maturing genotype with a longer growth cycle, whereas Borlaug is early-maturing and thus better suited for environments prone to late-season heat stress. Longer phenological phases in Norman could allow for greater biomass accumulation, but under Sahelian heat stress, this may expose the crop to terminal drought, thereby reducing yield stability [12]. Interestingly, establishment percentage did not differ significantly between varieties, implying that genotypic differences were more expressed in growth duration than in emergence vigor. This aligns with the findings of [10] [35], who reported that wheat varietal responses in West Africa are mainly driven by thermal and photoperiod sensitivity.

There were no significant (P > 0.05) differences between seasons for flowering, heading, or maturity, although establishment percentage tended to be higher in 2023 (151.3%) than in 2022 (129.7%). The higher establishment in 2023 may reflect more favorable early-season soil moisture conditions. Seasonal variations in Sahelian climates are common, often influencing wheat establishment and yield stability [38].

Means followed by the same letter(s) in the column within a treatment group are not significantly different at 5% level of probability using SNK.

The interaction between sowing date and variety on days to 50% flowering was significant and shown in Table 3. Results revealed that Norman significantly (P <0.01) took more days to reach 50% flowering, particularly when sown from 5th November to 15th December, compared other interaction combinations. This indicates that Norman has a longer growth duration and stronger sensitivity to photoperiod and temperature, whereas Borlaug flowered earlier across all sowing windows, reflecting its shorter life cycle. The three-way interaction of SD × V × Y on days to 50% flowering (Table 3) further showed that seasonal variability slightly influenced flowering time, with crops in 2023 generally requiring more days to flower than in 2022. Such variation is linked to differences in temperature and rainfall distribution, which are known to regulate wheat phenology in semi-arid environments [12][38].

Norman’s prolonged flowering under optimal sowing windows (mid-November to December) may enhance biomass accumulation and yield potential but increases its exposure to terminal heat and water stress if sowing is delayed. In contrast, Borlaug’s early flowering makes it more suitable for flexible sowing, particularly under early or late planting, supporting yield stability under Sahelian climate variability [18][16].

   Means followed by the same letter are not significantly different at 5% level of probability using SNK.

Means followed by the same letter(s) are not significantly different at 5% level of probability using SNK.

3.2 Plant height (cm)

Table 4 indicates that plant height was significantly (P < 0.001) influenced by sowing date and variety, but not by season. The tallest plants were recorded on 15th November, while 25th October and 1st January sowings produced the shortest. This suggests that mid-November planting provided optimum temperature and photoperiod conditions for vegetative growth. Norman consistently recorded taller plants than Borlaug, reflecting varietal differences in growth habit. These results agree with [8], who observed that optimum sowing windows enhance wheat stature, while delayed planting reduces growth due to terminal heat stress.

3.3 Number of spikes m^-2

The number of spikes per unit area differed significantly (P < 0.001) across sowing dates and varieties. 15th November planting produced the highest spike population, while both early (25th October) and late (1st January) sowings resulted in fewer spikes (Table 4). This reduction is likely due to suboptimal tillering temperatures and shortened vegetative phases in late sowing. Borlaug outperformed Norman in spike density, suggesting its superior tillering ability. These findings are consistent with [16], who reported that tiller survival and spike density are key yield determinants under optimal sowing windows.

3.4 Spike length (cm)

Spike length was also maximized under 15th November sowing, with reduced values under both early and late plantings (Table 4). The favorable thermal regime during this period likely prolonged assimilate partitioning to reproductive structures, increasing spike elongation. Norman exhibited longer spikes than Borlaug, reflecting inherent genetic potential. Similar findings were reported by [5] and corroborated by [3], were late sowing accelerated senescence, reducing spike development.

Number of seeds per spike

Sowing on 15th November significantly increased grain number per spike, while early and very late planting (25th October and 1st January) reduced this parameter (Table 3). Heat stress during anthesis in late planting likely impaired fertilization and kernel set. Interestingly, there was no significant varietal or seasonal effect, suggesting that spike fertility was more responsive to environmental conditions than genotype. Comparable outcomes were observed by [25] and further supported by [22], who noted that reproductive success in wheat is most sensitive to sowing date around flowering.

3.5 1000-grain weight (g)

Grain weight showed clear sowing date and variety effects. The 5th November sowing produced the heaviest grains, while 1st January planting had the lowest. The reduction in late sowing is attributable to the shortened grain-filling duration under elevated temperatures, reducing assimilate accumulation per kernel. Borlaug recorded slightly higher grain weight than Norman, highlighting genetic differences in assimilate translocation. These results align with [25] and confirm the more recent findings of [23], who emphasized the role of extended grain-filling period in achieving higher test weights.

3.6 Grain yield (kg ha^-1)

The combined influence of growth and yield attributes culminated in maximum yield under 15th November sowing (12,013 kg ha⁻¹), followed by 5th November and 15th December. Early planting (25th October) and very late sowing (1st January) significantly reduced yield, mainly due to reduced spike density, kernel number, and grain weight. Borlaug significantly outyielded Norman, despite Norman’s taller plants and longer spikes, suggesting Borlaug’s advantage lies in higher spike density and heavier grains. These findings are consistent with [24] and reinforced by recent studies [13] [20], which confirm that yield gains under optimal sowing dates are linked to cumulative improvements in growth duration, assimilate partitioning, and grain-filling efficiency.

Means followed by the same letter(s) in the column within a treatment group are not significantly different at 5% level of probability using SNK

Interaction Effects

The interaction between sowing date and variety on spike density and grain yield (Table 5) revealed that Borlaug sown on 15th November recorded the highest number of spikes/m² and yield, while very early (25th October) and very late sowing (1st January) in both varieties significantly reduced spike density. This could be attributed to favorable climatic conditions in November, which enhanced tillering and spike formation, consistent with the reports of [26]. On the other hand, 15^th November sowing in 2020 significantly yielded more spike density compared with rest of the interaction combination. The superior performance in mid-November sowing aligns with the findings of [1], who noted that optimal sowing dates ensure maximum utilization of radiation and moderate temperatures during critical growth stages.

Table 6 presents significant interaction of sowing dates and variety and SD x Year on 1000 grain weight, where Borlaug sown on 15th November produced the heaviest grains, closely followed by Norman on the same date, while the lowest grain weight was recorded in Norman sown on 1st January. This indicates that optimum sowing time, particularly mid-November, favored grain filling, while late sowing exposed plants to terminal heat stress, reducing assimilate translocation to grains. Similar findings were reported by [39] [28], who observed that mid-November sowing produced heavier grains compared to late planting.

On the other hand, sowing on and 15^th November x 2020 significantly had the heaviest 1000 seeds compared with rest of the interaction combination which indicates that optimum sowing time provided favorable temperature and radiation during the grain-filling period, which directly influenced assimilate partitioning into seeds. Grain weight is highly sensitive to the duration of grain filling, which depends on both genotype and environmental conditions at critical stages of development. According to [33], timely sowing aligns anthesis and grain filling with favorable thermal regimes, ensuring efficient photosynthate translocation. Similarly, [22] reported that mid-November sowing maximized kernel weight by avoiding terminal heat stress common in late sowings and cold stress in early sowings.

The superiority of the 2020 season further underscores the influence of seasonal variation. Adequate rainfall distribution and moderate temperatures in 2020 may have extended the grain-filling duration, leading to heavier kernels. This agrees with [37], who highlighted that seasonal weather variations significantly affect 1000-grain weight through their impact on source-sink dynamics. Furthermore, [2] observed that wheat sown in optimal windows achieves not only higher yields but also improved grain quality parameters such as test weight and 1000-grain weight.

The sowing date × year interaction (Table 7) further confirmed that 15th November 2023 produced the highest spike density and grain yield, while 25th October and 1st January sowing in both years gave the lowest yields. The superior performance in mid-November sowing aligns with the findings of [24] and [2], who noted that optimal sowing dates ensure maximum utilization of radiation and moderate temperatures during critical growth stages.

Figure 2 present a significant sowing date × variety × year interaction on grain yield, where Borlaug sown on 15th November 2023 achieved the highest yield, followed by Borlaug on 5th November and 15th December 2023. Norman consistently produced lower yields, indicating varietal differences in adaptability. Late sowing significantly reduced yields due to fewer spikes/m², lighter grains, and shorter grain-filling periods, corroborating the reports of [4].

The variety × year interaction on number of spike (Table 8) showed that Borlaug produced more spikes/m² than Norman, especially in 2023 in comparison with other interaction combination, suggesting better adaptability and tillering potential. This agrees with [33] who highlighted that timely sowing enhances productive tiller formation, which strongly correlates with yield.

The sowing date × variety × year interaction on spikes/m² (Figure 3) revealed that Borlaug sown on 5th and 15th November 2023 recorded the highest spike density, while Norman sown on 1st January recorded the lowest. This further emphasizes the critical role of mid-November sowing in achieving maximum yield potential, as confirmed by [15]. These findings underscore the importance of timely sowing in synchronizing crop growth with favorable microclimatic conditions, thereby sustaining wheat productivity in challenging environments.

Conclusion and Recommendation

Sowing date and varietal choice profoundly influence wheat yield performance. Mid-November sowing, especially with Borlaug, maximized yield components and grain productivity, whereas late sowing beyond December severely reduced yields. Therefore, timely sowing between 5^th-15th November using high-yielding varieties such as Borlaug is strongly recommended to sustain wheat productivity under semi-arid environments. Future studies should integrate climate-smart practices and genotype evaluation to further enhance resilience and productivity under shifting climatic patterns.

Competing Interests

Authors have declared that no competing interests exist.

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