Influence of Imazaquin Seed Treatment on Control of Striga gesnerioides and its Consequence on Yield and Yield Components of Selected Cowpea Genotypes

The effect of Imazaquin seed treatment on Striga control, yield, and yield components of cowpea were investigated in Nigeria, in 2010 and 2011 rainy seasons. Imazaquin at 0.00, 0.06, and 0.24 kg a.i. ha-1 was the main plot treatment; cowpea genotypes (Achishiru, IT97K-1263, IT97K-390-2, IT98K-133-1-1, TVU-1283, TVU-1542 and TVU-1908) were the subplots. The untreated control recorded the highest number of Striga m-2 which was 2.8 times higher than seed treatment with imazaquin at 0.06 kg a.i. ha-1, and 6.8 times higher than treatment at 0.24 kg a.i. ha-1. Achishiru had the most Striga infestation (4.29 m-2) in 2010 and TVU-1283 (5.61 m-2) in 2011; genotype IT97K-1263 had no Striga in 2010 and 2011. TVU-1542 and IT97K-390-2 recorded the highest grain yield in 2010 and 2011. Treating IT97K-390-2, IT98K-133-1-1 and TVU-1542 with imazaquin at 0.06 and 0.24 kg a.i. ha-1 reduced Striga parasitism in the field and increased grain yield and yield component of these genotypes. These treatment combinations are therefore recommended for Striga control. Keywords: genotypes, cowpea, imazaquin, Striga control, seed treatmen

Intensive cereal-legume–livestock systems in West African dry Savannas.

The dry savannas of West Africa are undergoing rapid transformation of agricultural practices owing to the rapid human and livestock population growth, increase in agricultural intensification and accelerated climate change which has increased the incidence and severity of diseases, pests and drought. The major constraints to agricultural production in the savanna include poor soil fertility, pests and diseases of crops and livestock, parasitic weeds such as Striga hermonthica, drought, and competition between crops and livestock for resources, Inadequate policies, weak institutional mechanisms, and poor linkages among farmers, and researchers prevent adoption of improved agricultural technologies that can combat these constraints. The risk of continuous cultivation on these poor and fragile soils is huge. Integrating crop and livestock production offers ways to increase production while protecting the environment. Over the years, research and development institutions have generated several agricultural technologies to alleviate the majority of the production constraints in the West African savannas. However, most development organizations use traditional extension methods that result in poor adoption of the improved technologies. The integration of crop and livestock production is particularly desirable in intensively farmed and densely populated areas with access to urban markets. Proper integration of these practices will diversify smallholder income and increase food security. Integrated genetic and natural resource management provides the keys improved eco-efficiency. This includes integrating pesticide use with cultural practices such as modified planting date and disease control; rotating/ intercropping cereals and legumes; use of pest resistant\tolerant cultivars to increase the effectiveness of pest control and reduce the need for pesticides; and improving soil fertility restoration/maintenance. Government and national institutions in West Africa are encouraged to scale-out these technologies to wider areas for increased benefit to farmers through the use of proven extension methods

Performance of semideterminate and indeterminate cowpeas relaycropped into maize in Northeast Nigeria

Field trials were conducted in 2005 and 2006 in Tilla (northern Guinea savanna) and Sabon-Gari (Sudan savanna) in northeast Nigeria to determine the performance of two improved cowpea varieties when relay-intercropped with early and late maize, 6 and 8 weeks after planting the maize. Grain yield, number of branches and number of pods per plant were higher for the variety IT89KD-288 than for IT97K-499-35, whether planted sole or relay-intercropped with maize. Grain yield was lower for IT97K-499-35 than for IT89KD-288 when relay-intercropped with maize irrespective of the maturity period of the companion maize crop. This may be due to the indeterminate growth habit and shade tolerance of IT89KD-288 which allowed a higher pod load than IT97K-499-35. However, relay-intercropping with early maize gave higher yield than relay-intercropping into late maize. Also relay-intercropping at 6 weeks after planting maize (WAP) gave a higher yield than relay-intercropping at 8 WAP. This therefore, suggests that introducing cowpea into short statured early maize may mean less competition for light and soil resources compared to taller late maize. Also introducing the cowpea earlier may allow the crop to make full use of soil moisture during the cropping season

PERFORMANCE OF COWPEA GROWN AS AN INTERCROP WITH MAIZE OF DIFFERENT POPULATIONS

Cereal-cowpea intercrops have a record of low yields in the West African savannah. Two potential ways to improve the yield of cowpea ( Vigna unguiculata Walp), when grown with maize ( Zea mays L.), is by manipulating the plant population of maize and using adapted cowpea cultivars. A field trial was conducted at Samaru in northern Guinea savannah of Nigeria, to determine the performance of semi-determinate and indeterminate cowpeas grown under maize populations of 0, 17,777, 26,666, and 53,333 plants ha-1. The radiation transmitted into cowpea was reduced by 50, 30 and 15% for a maize population of 53,333, 26,666 and 17,777 plants ha-1 respectively, compared with 0 plants ha-1. Maize population of 0 to 26,666 plants ha-1 favoured better cowpea performance compared with 53,333 plants ha-1 because at these lower plant populations, maize plants had lower leaf area indices which allowed maize canopy to transmit more light into the understorey cowpea. The negative effects of shade were more pronounced in the semi-determinate cowpea than in the indeterminate. Therefore, in high maize populations, indeterminate spreading cowpeas should be grown; while semi-determinate cowpeas should be planted in low to moderate maize populations because of their intolerance to severe shade.La culture des c\ue9r\ue9ales en association avec le ni\ue9b\ue9 a souvent \ue9t\ue9 associ\ue9e \ue0 un faible rendement dans les savanes Ouest-Africaines. Il existe deux fa\ue7ons probables d\u2019am\ue9liorer le rendement du ni\ue9b\ue9 ( Vigna unguiculata Walp) cultiv\ue9 en association avec le ma\uefs ( Zea mays L.) ; la manipulation de la densit\ue9 populationnelle du ma\uefs et l\u2019utilisation des vari\ue9t\ue9s de ni\ue9b\ue9 adapt\ue9es. Un essai en plein champ a \ue9t\ue9 r\ue9alis\ue9 \ue0 Samaru dans la partie nord de la savane de Guin\ue9e au Nigeria, afin de d\ue9terminer la performance de ni\ue9b\ue9s semi-d\ue9termin\ue9 et ind\ue9termin\ue9 cultiv\ue9s en association avec diff\ue9rentes densit\ue9s de ma\uefs (0, 17,777, 26,666, and 53,333 plants ha-1). Compar\ue9 \ue0 un champ sem\ue9 seulement au ni\ue9b\ue9, la radiation solaire transmise au ni\ue9b\ue9 \ue9tait r\ue9duite de 50, 30 et 15% respectivement pour des densit\ue9s de ma\uefs de 53,333, 26,666 and 17,777 plants ha-1. Une densit\ue9 de ma\uefs allant de 0 \ue0 26,666 plants ha-1 favorisait mieux la performance du ni\ue9b\ue9 qu\u2019une densit\ue9 de 53,333 plants de ma\uefs par ha. Ceci parce qu\u2019\ue0 cette faible densit\ue9, les plants de ma\uefs avaient une faible surface foliaire et pouvaient ainsi transmettre un rayonnement solaire suffisant au ni\ue9b\ue9. L\u2019effet n\ue9gatif de l\u2019ombre caus\ue9 par la couverture foliaire du ma\uefs \ue9tait plus prononc\ue9 sur le ni\ue9b\ue9 semi-d\ue9termin\ue9 que sur le ni\ue9b\ue9 ind\ue9termin\ue9. Il apparait alors, que le ni\ue9b\ue9 ind\ue9termin\ue9 devrait \ueatre cultiv\ue9 en association avec une forte densit\ue9 de ma\uefs, tandis que le ni\ue9b\ue9 semi-d\ue9termin\ue9 devrait \ueatre cultiv\ue9 en association avec une densit\ue9 de ma\uefs faible ou mod\ue9r\ue9

Science-based decision support for formulating crop fertilizer recommendations in sub-Saharan Africa

Open Access Article; Published online: 31 Jan 2020In sub-Saharan Africa, there is considerable spatial and temporal variability in relations between nutrient application and crop yield, due to varying inherent soil nutrients supply, soil moisture, crop management and germplasm. This variability affects fertilizer use efficiency and crop productivity. Therefore, development of decision systems that support formulation and delivery of site-specific fertilizer recommendations is important for increased crop yield and environmental protection. Nutrient Expert (NE) is a computer-based decision support system, which enables extension advisers to generate field- or area-specific fertilizer recommendations based on yield response to fertilizer and nutrient use efficiency. We calibrated NE for major maize agroecological zones in Nigeria, Ethiopia and Tanzania, with data generated from 735 on-farm nutrient omission trials conducted between 2015 and 2017. Between 2016 and 2018, 368 NE performance trials were conducted across the three countries in which recommendations generated with NE were evaluated relative to soil-test based recommendations, the current blanket fertilizer recommendations and a control with no fertilizer applied. Although maize yield response to fertilizer differed with geographic location; on average, maize yield response to nitrogen (N), phosphorus (P) and potassium (K) were respectively 2.4, 1.6 and 0.2 t ha−1 in Nigeria, 2.3, 0.9 and 0.2 t ha−1 in Ethiopia, and 1.5, 0.8 and 0.2 t ha−1 in Tanzania. Secondary and micronutrients increased maize yield only in specific areas in each country. Agronomic use efficiencies of N were 18, 22 and 13 kg grain kg−1 N, on average, in Nigeria, Ethiopia and Tanzania, respectively. In Nigeria, NE recommended lower amounts of P by 9 and 11 kg ha−1 and K by 24 and 38 kg ha−1 than soil-test based and regional fertilizer recommendations, respectively. Yet maize yield (4 t ha−1) was similar among the three methods. Agronomic use efficiencies of P and K (300 and 250 kg kg−1, respectively) were higher with NE than with the blanket recommendation (150 and 70 kg kg−1). In Ethiopia, NE and soil-test based respectively recommended lower amounts of P by 8 and 19 kg ha−1 than the blanket recommendations, but maize yield (6 t ha−1) was similar among the three methods. Overall, fertilizer recommendations generated with NE maintained high maize yield, but at a lower fertilizer input cost than conventional methods. NE was effective as a simple and cost-effective decision support tool for fine-tuning fertilizer recommendations to farm-specific conditions and offers an alternative to soil testing, which is hardly available to most smallholder farmers

Assessing the use of a drought‑tolerant variety as adaptation strategy for maize production under climate change in the savannas of Nigeria

Open Access Journal; Published online: 26 Apr 2021The Decision Support System for Agricultural Technology Transfer (DSSAT) was used to quantify the impact of climate change on maize yield and the potential benefits of the use of drought-tolerant maize variety over non-drought tolerant variety in savanna ecological zones of Nigeria. Projections of maize yields were estimated for three locations representing different agro-climatic zones and soil conditions, in the mid-century (2040–2069) and end-century (2070–2099) under representative concentration pathways scenarios (RCP 4.5 and 8.5) against the baseline period (1980–2009). Relative to the baseline period, the ensemble Global Circulation Models (GCMs) predicted significant increase in minimum and maximum temperatures and seasonal rainfall across the sites. In the mid-century, ensemble GCMs predicted temperatures increase between 1.7–2.4 °C for RCP4.5 and 2.2–2.9 °C for RCP8.5. By end-century, the temperature increases between 2.2–3.0 °C under RCP4.5 and 3.9–5.0 °C under RCP8.5. Predicted seasonal rainfall increase between 1.2–7% for RCP4.5 and 0.03–10.6% for RCP8.5 in the mid-century. By end of century, rainfall is expected to increase between 2–6.7% for RCP4.5 and 3.3–20.1% for RCP8.5. The DSSAT model predictions indicated a negative impact on maize yield in all the selected sites, but the degree of the impact varies with variety and location. In the mid-century, the results showed that the yield of the non–drought tolerant maize variety, SAMMAZ-16 will decline by 13–19% under RCP4.5 and 19–28% under RCP8.5. The projection by end-century indicates a decline in yield by 18–26% under RCP4.5 and 38–47% under RCP8.5. The yield of the drought-tolerant variety is projected to decline by 9–18% for RCP4.5 and 14–25% for RCP8.5 in the mid-century and 13–23% under RCP4.5 and 32–43% under RCP8.5 by the end-century. The higher temperatures by both emission scenarios (RCP 4.5 and 8.5) were primarily shown to cause more yield losses for non-drought-tolerant variety than that of the drought-tolerant variety. There will be 1–6% less reduction in yield when drought-tolerant variety is used. However, the higher yield reductions in the range of − 13 to − 43% predicted for the drought-tolerant variety by the end of the century across the study areas highlighted the need to modify the maize breeding scheme to combine both tolerances to drought and heat stresses in the agro-ecological zones of northern Nigeria