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Striga hermonthica (Del.) Benth infestation is one of the major constraints to maize production in the Nigeria savannas. The application of nitrogen fertilizer to Striga-resistant hybrids may reduce Striga infection and increase grain yields. The objective of this study was to assess the performance of six maize hybrids at low (30 kg ha−1) and high (120 kg ha−1) nitrogen application under natural infestation with Striga in northern Nigeria in 2014 and 2015. The two nitrogen rates and the six hybrids were arranged in a split-plot design with three replications. The nitrogen treatment was assigned to the main plot while the maize hybrids were assigned to the subplot. Data were collected on number of emerged Striga plants, Striga damage score, total dry matter and grain yield. Results showed that the application of nitrogen at 120 kg ha−1 reduced the number of Striga plants by 58% compared to application at 30 kg N ha−1 in Kafin Madaki and by 48% in Tudun Wada. Nitrogen application at 120 kg N ha−1 also reduced Striga damage rating by 22% in Kafin Madaki and by 33% in Tudun Wada. Both the commercial hybrid (OBASUPER 1) and the susceptible hybrid (8338-1) exhibited higher Striga damage ratings compared to the new hybrids at both locations. Grain yield was 86 and 98% higher in Kafin Madaki and Tudun Wada, respectively, when N was applied at 120 kg N ha−1 than at 30 kg N ha−1. The hybrids M1124-3 and M1227-14 produced grain yields that were significantly higher than those of the other hybrids in all locations. Our results showed that the application of 120 kg N ha−1 to Striga-resistant maize hybrids will reduce Striga infection and increase grain yield.

Increasing delays in the onset of the rainy season and extended dry spells in the Nigerian savannas are complicating the determination of optimal planting dates for rain-fed crops, which increases risks for farmers. This study evaluated the impact of planting dates on soybean [Glycine max (L.) Merr.] performance to identify optimal planting dates for different soybean varieties in two agroecological zones (AEZs) of Nigeria. The study involved six planting dates (15 June, 22 June, 29 June, 6 July, 13 July, and 20 July) and three soybean varieties (TGX-1835-10E, TGX-1951-3F, TGX-1904-6F). Results showed significant differences in growth and yield parameters based on location, variety, and planting date. In the Sudan savanna (SS), AEZ at BUK-Kano, optimal yields (>1500 kg ha−1) were achieved when planting TGX-1835-10E and TGX-1951-3F from 15 to 29 June and TGX-1904-6F on 15 June. Planting beyond 29 June reduces yields by 12–55% for TGX-1835-10E and 27–63% for TGX-1951-3F. For TGX-1904-6F, planting after 15 June reduces yields by 27–90%. In the Northern Guinea savanna (NGS) AEZ at Zaria, optimal yields (>1500 kg ha−1) were obtained when planting TGX-1835-10E and TGX-1951-3F from 15 June to 6 July, and TGX-1904-6F between 15 to 29 June. Delaying planting beyond these dates significantly reduced yields by 18–31% for TGX-1835-10E and 12–20% for TGX-1951-3F and 10–41% for TGX-1904-6F. [ABSTRACT FROM AUTHOR]

Snake gourd botanically known as Trichosantes cucumerina locally called tomato agwo. T.cucumerina is considered a neglected and underutilised crop. Detailed characterisation of this crop is not known in Nigeria and other African countries. This study was done to access fourteen accessions of T. cucumerina from Nigeria using Internal Transcribed Spacer (ITS). The fourteen accessions from different ecological regions were sequenced with ITS1 and ITS4 by direct PCR products. The results obtained were at minimum (570) and maximum (580) base pairs. The query coverage ranging from 99.4 % to 100 % affirms positive amplification and sequencing of snake gourd ecotypes using ITS1 and ITS4. The phylogenetic tree of the characterization group T. cucumerina was divided into three clusters. The phylogenetic tree of the characterization grouped T.cucumerina into three clusters. The genetic distances between the samples revealed that Ukwa, NACGRAB, Ikwuano, Oshogbo, Ikom, and Rumibekwe were closely related. Benin, Nasarawa, Oye-Ekiti, Ilorin, and NHST-0583 shared no genetic relationship as revealed by their genetic distances. The genetic distance ranged from 0.217 - 2.010. T. cucumerina landraces studied in Nigeria thirteen were T. cucumerina var anguina. The NHST -0583 from the seed center was the only T.cucumerina var cucumerina in Nigeria. This was blasted on the National Center for Biotechnology Information (NCBI) website. The sequenced blast in the NCBI data website was to be similar to accession numbers GU059528.1 and GQ240883.1 respectively. These have given scientists critical knowledge regarding T. cucumerina molecular breeding in Nigeria [ABSTRACT FROM AUTHOR]

Fusarium wilt caused by Fusarium oxysporum f. sp tracheiphilum (Fot) is a soil-borne fungal disease of significant constraint to cowpea production in West Africa. The disease infection can cause up to 100% yield loss in highly infested fields. The most effective control strategy is the use of resistant varieties. Sixty cowpea germplasm collections were screened for resistance to F. oxysporum. The result revealed that only two (TVu 134 and TVu 410) of the germplasm showed a high level of resistance when subjected to artificial epiphytotic and innovative seedling root dip screening methods using three inoculum concentration levels. These two cultivars can be used directly by farmers or as potential donors for developing resistant cultivars against F. oxysporum. The study also identified useful polymorphic SSR markers associated with resistant and susceptible parents, which will significantly enhance the breeding programs in developing varieties' resistance to the disease. [ABSTRACT FROM AUTHOR]

Cowpea is a multifaceted crop; however, considerable challenges affect the production of this crop despite its comparatively better adaptation to harsh environments. Most smallholder farmers in West Africa cultivate this crop in intercropping systems where its low plant population does not allow the full expression of the cultivars' yield potential. This is because most varieties currently grown in intercrop have been developed in and for monocropping, although some breeding programs recently have focused on intercrop systems. This study, therefore, aimed to evaluate the performance of some newly developed cowpea breeding lines for adaptation to intercropping systems. Firstly, an on-station field experiment was conducted in 2018. The selected promising lines and a standard check were evaluated in three locations in an intercropping system and on-farm trials. Significant differences were observed among the cowpea genotypes for all the traits measured. Two improved lines, UAM14-122-17-7 and UAM14-123-18-3, had superior grain and fodder yields under sole and intercropping systems and in different agroecological systems, revealing their adaptability. Based on our findings, UAM14-122-17-7 and UAM14-123-18-3 are recommended for a cereal-cowpea mixture because they are adapted to intercropping and produce high-grain yield under intercrop and sole-cropping systems. [ABSTRACT FROM AUTHOR]

Cowpea improvement has continued to play key roles in the quest for national food security. This work elucidated the molecular genetic diversity and phylogenetics among four released cowpea varieties (FUAMPEA-1, FUAMPEA-2, FUAMPEA-3 AND FUAMPEA-4). DNA was extracted from 14 day old seedlings using the CTAB method. A total of nine (9) SSR (Simple Sequence Repeats) markers were employed in DNA amplifications. Binary matrix was generated from banding profiles of gel images and uploaded into the Minitab 17.0 software for analysis. Polymorphic Information Content (PIC) was computed for the primers and cowpea varieties. Cluster analysis was carried out using the Single Linkage method measured on Euclidean Distance. Four primers (CLM1190, CLM0342, RB38 and RB7) produced maximum of two bands each resulting in 15.4% polymorphism and 0.977 Polymorphism Information Content (PIC). Varietal Polymorphic Content (VPC) varied from 15.4% in FUAMPEA-2 as the lowest to 38.5% in FUAMPEA-1 as the highest. FUAMPEA-1 had the lowest genetic similarity index (19.82). Dendrogram further showed that FUAMPEA-2 and FUAMPEA-3 were more closely related than others with about 46.55 similarity index. Therefore, FUAMPEA-1 was the most divergent and genetically diverse variety followed by FUAMPEA-4. These are potential genetic resource material that can used to develop more cultivars when their inherent agronomic traits and genes coding for the traits are identified and tapped. [ABSTRACT FROM AUTHOR]

Several maize (Zea mays L.) hybrids have been developed and commercialized in the Nigeria savannas, but limited informationis available on how they perform at plant densities higher than the recommended density of 53,333 plants ha-1. Therefore, field trials were conducted in northern Nigeria in 2015 and 2016 at two locations with contrasting rainfall amount to evaluate the performance of selected maize hybrids at plant densities of 53,333 and 88,888 plants ha-1. All maize hybrids had higher grain yields, total dry matter, ears m-2, and number of grains m-2 at 88,888 than at 53,333 plants ha-1 at both locations. The magnitude ofincreases in yield when plant density was increased to 88,888 plants ha-1 was, however, higher for the new hybrids than for the old commercial hybrids. In Tudun Wada, five hybrids produced significantly higher mean grain yields than the remaining hybrid sat both plant densities. One of the hybrids (M1227-12) produced the highest grain yield at both planting densities at this location. In Samaru Zaria, the hybrid M1227-12 produced the highest grain yield only at 53,333 plants ha-1 at this location, whereas M0926-8 produced the highest yield at 88,888 plants ha-1. The 500-grain weight was 7-8% lower at 88,888 plants ha-1 than at 53,333 plantsha-1, which was offset by a significant increase in grain number. Our results showed that farmers in the Nigeria savannas can increase planting density of hybrid maize to 88,888 plants ha-1 and significantly increase their yields. [ABSTRACT FROM AUTHOR]

Grain legumes are nutritionally important components of smallholder farming systems in sub-Saharan Africa and Asia. Unfortunately, limited access to quality seed of improved varieties at affordable prices due to inadequate seed systems has reduced their contribution to improving nutrition and reducing poverty in these regions. This paper analyses four seed systems case studies: chickpea in Ethiopia and Myanmar; cowpea in Nigeria; and tropical grain legumes in Nigeria, Tanzania and Uganda highlighting outcomes, lessons learned, and the enabling factors which supported the successful innovations. All four case studies highlighted at least some of the following outcomes: increased adoption of improved varieties and area planted; increased productivity and income to farmers; improved market access and growth; and significant national economic benefits. Important lessons were learned including the value of small seed packets to reach many farmers; the value of innovative partnerships; capacity building of value chain actors; and continuity and coherence of funding through Tropical Legumes projects II and III and the recently funded Accelerated Varietal Improvement and Seed Delivery of Legumes and Cereals in Africa (AVISA) project. Successful adoption of innovations depends not just on the right technologies but also on the enabling environment. The case studies clearly showed that market demand was correctly identified, establishment of successful partners and institutional linkages overcame constraints in production and delivery of improved seed to smallholders, and fostered conducive policies supported national seed systems. All were integral to seed system viability and sustainability. It is hoped that these examples will provide potential models for future grain legume seed systems efforts. In addition, the analysis identified a number of areas that require further research. [ABSTRACT FROM AUTHOR]

This article evaluates the impact of cowpea market participation on household food security and income in northern Nigeria. Using household survey data from a representative sample of over 1,500 farm households and applying a combination of instrumental variable techniques and dose–response functions, we found that cowpea market participation had a statistically significant positive impact on household food security and income. Cowpea market participation increased food expenditure by 1.6% and household income by 0.7% with a 10 unit increase in the quantity of cowpea sold. These results underscore the importance of cowpea market participation for household food security and income improvement. We also found that selling cowpea to rural and urban traders significantly increased household income, food expenditure, and food security. Results show that selling cowpea to rural and urban traders increased household income by 17% and 13%, respectively. The results point to the need for an enabling policy environment and public infrastructure to enhance market participation of farmers and traders. Public infrastructure investments in the form of feeder road construction and maintenance in the distant villages are encouraged, which in the long run can translate into improved cowpea productivity and welfare of smallholder farmers. [ABSTRACT FROM AUTHOR]

Striga hermonthica infestation causes significant losses of maize yield in the Nigerian savannas and several technologies have been developed and promoted to control Striga in maize. However, since no single technology has been found to be effective against Striga, integrated management is needed to achieve satisfactory and sustainable Striga control. Both on-station and on-farm trials were undertaken from 2013 to 2015 in Bauchi and Kano States of Nigeria to evaluate the performance of integrated Striga control technologies. In the on-station trials, a soybean–maize rotation did not suppress Striga in maize in either location. However, nitrogen application suppressed and reduced Striga infection, except in Bauchi in 2014. The soybean–maize rotation accompanied by N application reduced Striga damage in both locations. On farmers' fields, rotating soybean with maize significantly reduced Striga infection. At the same time, the use of maize varieties with a combined tolerance to drought and resistance to Striga parasitism also increased maize grain yield on farmers' fields, probably due to three factors: a reduction in Striga infection, reduced effects of a mid-season moisture deficit, and increased uptake of nutrients from the soil. We concluded that the use of Striga-resistant maize varieties in combination with the application of N fertilizer and rotation with soybean could increase the productivity of maize in Striga-infested fields in the Nigerian savannas. [ABSTRACT FROM AUTHOR]

There are several hurdles to ensure sustainable seed production and consistent flow of improved legume varieties in sub‐Saharan Africa (SSA) and South Asia (SA). The unreliable demand, autogamous nature of most of the grain legumes, and slow variety replacement rate by smallholder farmers do not provide strong incentive for private seed companies to invest in legume seed business. Unless a well thought‐out and comprehensive approach to legume seed delivery is developed, current seed shortages will continue, eroding emerging market opportunities. The experiences reported here are collated through a 10‐year partnership project, the Tropical Legumes in SSA and SA. It fostered innovative public–private partnerships in joint testing of innovative market‐led seed systems, skills and knowledge enhancement, de‐risking private sector initiatives that introduced in new approaches and previously overlooked entities in technology delivery. As new public and private seed companies, individual seed entrepreneurs and farmer organizations emerged, the existing ones enhanced their capacities. This resulted in significant rise in production, availability and accessibility of various seed grades of newly improved and farmer demanded legume varieties in the target countries. [ABSTRACT FROM AUTHOR]

Legumes are important components of sustainable agricultural production, food, nutrition and income systems of developing countries. In spite of their importance, legume crop production is challenged by a number of biotic (diseases and pests) and abiotic stresses (heat, frost, drought and salinity), edaphic factors (associated with soil nutrient deficits) and policy issues (where less emphasis is put on legumes compared to priority starchy staples). Significant research and development work have been done in the past decade on important grain legumes through collaborative bilateral and multilateral projects as well as the CGIAR Research Program on Grain Legumes (CRP‐GL). Through these initiatives, genomic resources and genomic tools such as draft genome sequence, resequencing data, large‐scale genomewide markers, dense genetic maps, quantitative trait loci (QTLs) and diagnostic markers have been developed for further use in multiple genetic and breeding applications. Also, these mega‐initiatives facilitated release of a number of new varieties and also dissemination of on‐the‐shelf varieties to the farmers. More efforts are needed to enhance genetic gains by reducing the time required in cultivar development through integration of genomics‐assisted breeding approaches and rapid generation advancement. [ABSTRACT FROM AUTHOR]

SUMMARY: Field studies were conducted during the 2014 and 2015 wet seasons at Zaria in the northern Guinea savanna and at Iburu in the southern Guinea savanna of Nigeria to determine the productivity of maize–soybean intercropping system. There were four treatment combinations in the experiment: sole maize; sole soybean; maize spaced at 50 cm and intercropped with soybean; and maize spaced at 65 cm and intercropped with soybean. The experiment was laid out in a randomized complete block design with three replications. The results showed that sole cropped maize and soybean generally outperformed the intercropped component crops. Land Equivalent Ratio (LER) was greater than 1 for all the intercrop treatments, indicating that it is advantageous to grow maize and soybean in association than in pure stands. Except for 2014 in Zaria, LER for intercropped maize spaced at 50 cm was higher than that for maize spaced at 65 cm. Gross Monetary Value (GMV) was generally higher for intercrops than sole crops except in Iburu in 2015 where GMV for intercropped maize spaced at 65 cm was similar to those of sole maize and soybean. Monetary Advantage Index (MAI) was positive for all intercrop treatments in both locations and years, which shows definite yield and economic advantages compared to the sole cropping systems. This suggests that farmers can intercrop soybean and maize with maize spaced at 50 cm and 65 cm. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated the inheritance of resistance to Fusarium oxysporum f.sp. tracheiphilum (Fot) in cowpea lines. Resistant and susceptible cowpea lines were crossed to develop F1, F2 and backcross populations. Reaction to Fot was evaluated in 2015 and 2016 using seed soak and modified root‐dip inoculation methods. The expression of resistance reaction in the F1 and segregation in F2 generations indicated the role of dominant gene controlling Fot in cowpea. These results were further supported by the result of backcross (BC1P1F1 and BC1P2F1) progeny tests. The backcross of F1 with the resistant parent produced progeny that were uniformly resistant, whereas backcross of F1 with the susceptible parent produced progeny that segregated into 1:1 ratio. The F2 segregation ratio in the reciprocal cross showed no evidence of maternal effect in the inheritance of the resistance. Allelism test suggests that the gene for resistance in TVu 134 was the same in TVu 410 and TVu 109‐1. We also identified an SSR marker, C13‐16, that cosegregated with the gene conferring resistance to Fot in cowpea. [ABSTRACT FROM AUTHOR]

Striga gesnerioides (Willd) Vatke, is a major destructive parasitic weed of cowpea (Vigna unguiculata (L.) Walp.) which causes substantial yield reduction in West and Central Africa. The presence of different virulent races within the parasite population contributes to significant genotype 9 environment interaction, and complicates breeding for durable resistance to Striga. A 3-year study was conducted at three locations in the dry savanna agro-ecology of Nigeria, where Striga gesnerioides is endemic. The primary objective of the study was to identify cowpea genotypes with high yield under Striga infestation and yield stability across test environments and to access suitability of the test environment. Data collected on grain yield and yield components were subjected to analysis of variance (ANOVA). Means from ANOVA were subjected to the genotype main effect plus genotype 9 environment (GGE) biplot analysis to examine the multi-environment trial data and rank genotypes according to the environments. Genotypes, environment, and genotypes 9 environment interaction mean squares were significant for grain yield and yield components, and number of emerged Striga plants. The environment accounted for 35.01%, whereas the genotype 9 environment interaction accounted for 9.10% of the variation in grain yield. The GGE biplot identified UAM09 1046-6-1 (V7), and UAM09 1046-6-2 (V8), as ideal genotypes suggesting that these genotypes performed relatively well in all study environments and could be regarded as adapted to a wide range of locations. Tilla was the most repeatable and ideal location for selecting widely adapted genotypes for resistance to S. gesnerioides. [ABSTRACT FROM AUTHOR]

Historically, conventional breeding has been the primary strategy used to develop a number of Striga-resistant varieties currently grown in the Sahel of Western Africa. In this study, we have successfully developed and applied a marker-assisted selection strategy that employs a single backcross programme to introgress Striga resistance into farmer preferred varieties of cowpea for the Nigeria savannas. In this strategy, we have introduced the Striga resistance gene from the donor parent IT97K-499-35 into an elite farmer preferred cowpea cultivar 'Borno Brown'. The selected 47 BC1F2 populations confirmed the recombinants with desirable progeny having Striga resistance gene(s). The 28 lines selected in the BC1F2:4 generation with large seed size, brown seed coat colour and carrying marker alleles were evaluated in the field for resistance to Striga resistance. This led to the selection of a number of desirable improved lines that were immune to Striga having local genetic background with higher yield than those of their parents and standard varieties. [ABSTRACT FROM AUTHOR]

Insect pests are major constraint to cowpea production in northern Nigeria causing yield losses up to 70%. Several cowpea varieties have been developed and delivered to farmers by IITA over the past four decades. These varieties have varying degrees of resistance to insect pest attacks. A field study was established in northern Nigeria to determine the response to insecticide spraying of old cowpea varieties developed in the late 1970s and new varieties developed in the 2000s in order to determine whether new varieties have lesser requirement for spraying with insecticides than the old ones. The result revealed that the new cowpea varieties developed in the 2000s require more spraying than the old varieties developed in the 1970s. Infestations by the insect pests, maruca (Maruca virataFabricius) and flower thrips (Megalurothrips sjostedtiTrybom) were significantly less at zero and 1 spray for old varieties than for the new varieties. Old varieties also produced significant higher grain yield at zero and 1 spray compared with new varieties. Newer varieties require more spray to maximise yield gain. [ABSTRACT FROM AUTHOR]

Soybean (Glycine max) is a major cash crop in the savannas of Nigeria although productivity is typically constrained by poor soil fertility. The objective of this research was to determine the interactive effect of N and P on soybean productivity in the northern Guinea and Sudan savannas of northeast Nigeria. Experiments were conducted using locally adapted early and late maturing cultivars. Two rates of N and three rates of P fertilizer were also compared at both sites over two years. At both sites, pods plant−1 and seed yield were higher in 2006 than in 2007, possibly due to better rainfall distribution in 2006. Nitrogen fertilizer had no significant effect on seed yield or pods plant−1. Application of P fertilizer increased pods plant−1 by 40–66%. Averaged across site and year, seed yield with no P was 1057.2 kg ha−1 while yield with 20 and 40 kg ha−1 P were 1941.0 kg ha−1 and 2371.5 kg ha−1, respectively. No significant interaction effect between N and P fertilizer on seed yield and pods plant−1 was observed. The late maturing cultivar yielded less than the earlier maturity group cultivar in 2007 likely due to moisture stress. For optimum seed yield 40 kg of P fertilizer ha−1 is recommended for soybean production in both locations. Our results suggest that N fertilizer is not critical for soybean production in this area. [ABSTRACT FROM PUBLISHER]

Sorghum (Sorghum bicolor [L.] Moench) is one of the most important cereal crops grown in the dry savannas and semi-arid regions of West Africa under rain-fed conditions. Although total sorghum production in Nigeria has increased over the years, the average grain yield on farmers' fields has remained low. A two-year trial was conducted to evaluate the effect of planting dates on three exotic sorghum cultivars (P9402, P9405, and PSL985061) and an improved local cultivar (KSV 8) under natural infestation with Striga hermonthica in northeast Nigeria. At Nzuda, the highest yield was obtained when planting was carried out on 19 July 2006 and on 5 July 2007. The decline in yield in 2007 as planting dates increased was largely due to early cessation of rain, which affected grain yield. At Sabon-Gari, KSV 8 and P9402 produced comparable grain yields that were higher than the yields of other cultivars at all planting dates. Grain yields of KSV 8 and P9402 were greater for 5 July than for the other planting dates and decreased significantly as the planting date was delayed, probably due to long maturity period. The highest grain yields were obtained from P9405 and PSL985061 when planted on 12 July and 19 July, respectively. KSV 8 had the highest number of emerged Striga plants at both locations. The number of emerged Striga plants under KSV 8 was 4.0-5.1 times higher at Nzuda and 2.4-2.6 times higher at Sabon-Gari than the number on the exotic cultivars at those locations. Among the exotic cultivars, differences in the number of emerged Striga plants were not significant. Farmers in the zone would maximize sorghum yield if improved cultivars are planted at the appropriate dates in Striga infested fields. [ABSTRACT FROM AUTHOR]

A number of improved varieties have been developed by the International Institute of Tropical Agriculture (IITA), combining diverse plant type with resistance or tolerance to several diseases, insect pests, and parasitic weeds and possessing other good agronomic traits. Trials were established with farmers to evaluate several new IITA-bred cowpea varieties on-farm in a process of participatory varietal selection. Central to this has been a 'mother-daughter' approach with researcher-managed 'mother' trials and farmer-managed 'daughter' trials in order to combine researchers' and farmers' criteria in evaluation of new varieties. In both set of trials, new varieties IT89KD-391, IT97K-499-35, and IT89KD-288 were favoured by farmers because of their high grain and fodder yields. Farmers have also shown interest in the continuous use of a local variety Kanannado Brown. It is suitable for relay intercropping; having a creeping habit, and the ability to smother weeds. The brown seeds fetch higher market prices. The implications are that improved cowpea varieties should be suitable for relay-intercropping and controlling weeds, be brown in colour, have large grain size, be pest resistant as well as give high yields of grain and fodder. At the same time, it is important that the farmer's criteria should be considered in breeding and varietal selection programmes. [ABSTRACT FROM AUTHOR]

Field studies were conducted in northeast Nigeria to evaluate the response of early and late-maturing maize varieties infested with natural populations of Striga to different rates of nitrogen (N) fertilizer. There were significant reductions in the number of emerged Striga at 120 kg N ha-1 for the early varieties and at 60 and 120 kg N ha-1 for the late varieties. The number of emerged Striga only significantly differed among the late varieties. Averaged across varieties, grain yield of the early varieties was 144% higher at 60 kg N ha-1 and 192% higher at 120 kg N ha-1 than without added N. For the late varieties the increase in grain yield was 85% higher at 60 kg N ha-1 and 144% higher at 120 kg N ha-1 than without added N. Among the early varieties, TZE COMP4 C3 had significantly lower grain yield than the other varieties. Among the late varieties, grain yields of 8338-1-1 and TZB-SR were significantly lower than in the other varieties. Our results show that the application of 60-120 kg N/ha to Striga resistant or tolerant varieties may reduce damage and increase grain yield. Higher economic rates of return was obtained at N rates of 60-120 kg N/ha than the other rates. [ABSTRACT FROM AUTHOR]

Knowledge of the genetic structure and diversity of germplasm collections is crucial for sustainable genetic improvement through hybridization programs and rapid adaptation to changing breeding objectives. The objective of this study was to determine the genetic diversity and population structure of 281 International Institute of Tropical Agriculture (IITA) soybean accessions using diversity array technology (DArT) and single nucleotide polymorphism (SNP) markers for the efficient utilization of these accessions. From the results, the SNP and DArT markers were well distributed across the 20 soybean chromosomes. The cluster and principal component analyses revealed the genetic diversity among the 281 accessions by grouping them into two stratifications, a grouping that was also evident from the population structure analysis, which divided the 281 accessions into two distinct groups. The analysis of molecular variance revealed that 97% and 98% of the genetic variances using SNP and DArT markers, respectively, were within the population. Genetic diversity indices such as Shannon's diversity index, diversity and unbiased diversity revealed the diversity among the different populations of the soybean accessions. The SNP and DArT markers used provided similar information on the structure, diversity and polymorphism of the accessions, which indicates the applicability of the DArT marker in genetic diversity studies. Our study provides information about the genetic structure and diversity of the IITA soybean accessions that will allow for the efficient utilization of these accessions in soybean improvement programs, especially in Africa. [ABSTRACT FROM AUTHOR]

Abstract: A 2-year field study was conducted to assess the effect of weed competition on the performance of upland rice cultivars in the savannas of Nigeria. A split-plot design was used with three weeding levels as the main plot treatments and the rice cultivars CG 14, ITA 150, WAB 56-104, NERICA1, NERICA2, and NERICA4 as the subplots. Grain yield, spikelets plant−1 and days to flowering differed significantly in plots weeded once or twice. Weed dry weight was negatively correlated with grain yield. Grain yield in all cultivars was over 50% less in the unweeded plots than in plots weeded once or twice. At Sabon-Gari, NERICA1 (unweeded or weeded twice), and NERICA4 (weeded once) were the most profitable. At Tilla, NERICA4 was the most profitable when weeded once or twice. Results showed that, given the profitability levels under the different weeding regimes, farmers would have higher marginal returns if they grew NERICA1 at Sabon-Gari and NERICA4 at Tilla and weed their rice plots twice. [Copyright &y& Elsevier]

The cultivation of soybean is increasing in the savannas of Nigeria due to its widespread use in the food and feed industry. Production is, however, constrained by low soil phosphorus (P) levels in northeast Nigeria. This study evaluated four soybean varieties for their response to three rates of P in two agro-ecozones in 2004 and 2005. Experimental design was a split-plot arrangement of treatments with three replications. The main plots were assigned the P treatments and subplots were soybean cultivars randomised within the main plots. The studies found that soybean responds to P application but differences between 20 and 40 kg P/ha were not significant, despite low test P levels. This may be due to limitations in other nutrients. More studies are needed to determine the synergistic effect of P and other nutrients on soybean growth and yield. Soybean growth and seed yield were lower in 2004 than in 2005 because trials were established comparatively late in 2004 and crops were therefore affected by late season moisture stress. There is, therefore, a need to establish the appropriate time for planting soybean in these zones. Late maturing varieties produced higher yields than early maturing varieties in 2005 probably due to early planting which allowed full use of the growing season. [ABSTRACT FROM AUTHOR]

Use of small doses of imazapyr and pyrithiobac for seed coatings of imazapyr-resistant maize hybrids (IR-Maize) offers an effective means to control Striga hermonthica. Field trials were conducted in Bauchi and Kano States of Nigeria in 2014 and 2015 under heavy Striga infestation to evaluate the potential effectiveness of herbicide coated hybrids maize on Striga control in farmers' field. Results showed that herbicide coated seeds reduced number of emerged Striga per m2 and Striga damage symptoms in farmers' fields in all the locations. In Kano the number of emerged Striga was 4.9 to 7.9 times less in herbicide treated hybrids in comparison with those of the same hybrids planted without herbicide treatment. The Striga-resistant open pollinated variety (OPV) (TZL COMP1 SYN) had 6.7 to 8.0 times more Striga than the treated hybrids. In Bauchi, the number of emerged Striga on the untreated IR-maize hybrids were over four-times higher on the treated IR-maize hybrids than on the untreated hybrids. The Striga-resistant OPV check had four-times more Striga than the treated IR-maize hybrids and twice more than the untreated IR-maize hybrids across the two years. However, the effects of herbicide seed coating on grain yields were not consistent because of strong seasonal effects. The result revealed that coating of imazapyr-resistant hybrid maize seeds with imazapyr was effective in reducing Striga infestation in farmers' fields. Although herbicide seed coating did not give consistent yield advantages of the hybrids over the untreated checks, a combination of herbicide seed treatment and genetic resistance to Striga would serve as an effective integrated approach that could significantly reduce the parasite seed bank from the soil and prevent production of new seeds. The IR-hybrids and the OPV checks contained Striga resistance/tolerant genes that protected them against drastic yield loss in the Striga infested fields in both Bauchi and Kano. [ABSTRACT FROM AUTHOR]

We used the CROPGRO-Soybean model to simulate the production potential of rainfed soybean in northeast Nigeria. Data from ten soybean experiments conducted under optimal conditions in 2016–2018 at Kano and Dambatta in the Sudan savanna (SS) agroecological zone were used to determine the cultivar coefficients and calibrate the model for the varieties TGX 1448–2E and TGX1951–3 F. The model was evaluated with data from four phosphorous response trials conducted at Zaria and Doguwa in the northern Guinea savanna (GS) of Nigeria between 2016 and 2018. Results show that the CROPGRO-Soybean model was able to accurately simulate soybean growth and grain yield with low RMSE and high d -index values. Consequently, the model was used to investigate the rainfed yield potential of the two varieties in 24 sites in northeast Nigeria under different sowing windows using 30-year (1985–2014) weather data. The result shows that soybean can be grown in northeast Nigeria, but yield performance is dependent on location, variety and sowing window. The simulated yield was higher in the SS than in the GS agro-ecozone despite the longer growing period in the later. Low yield was simulated for TGX 1448–2E for most of the sites. The yield of TGX1951–3 F was above a threshold of 1500 kg ha−1 in 5 out of 12 sites in the GS and 7 out of 12 sites in the SS, suggesting that this variety is the most suitable for cultivation in northeast Nigeria. Sowing TGX 1951–3 F can be delayed to July 16 at Gwaskara, Nasarawo Demsa and Tawa in the GS and at Briyel, Lakundum, Jara Dali, Kurbo Gayi, and Mathau in the SS with a low-risk of crop failure. The desired yield will be achieved at Chikala and Puba Vidau with a significantly low risk of crop failure for all sowing windows. The results from this study suggest that the CSM-CROPGRO-Soybean model can be a valuable tool in determining the right variety and sowing window for soybean production in targeted agroecological zones in northeast Nigeria. • The CROPGRO-Soybean model was calibrated and validated for two varieties of soybean TGX1951–3 F and TGX1448-2E. The model accurately reproduced the observed values. • A 30-year seasonal analysis showed that the simulated grain yield was generally higher in the Sudan savanna (SS) than in the Guinea savanna (GS) zone. • Higher yields were simulated for TGX1951–3 F than for TGX 1448-2E across planting windows and sites. • Best sowing window depends on location and variety, but TGX1951–3 F generally has a wider sowing window than TGX1448-2E [ABSTRACT FROM AUTHOR]

Knowledge of the genetic structure and diversity of germplasm collections is crucial for sustainable genetic improvement through hybridization programs and rapid adaptation to changing breeding objectives. The objective of this study was to determine the genetic diversity and population structure of 281 International Institute of Tropical Agriculture (IITA) soybean accessions using diversity array technology (DArT) and single nucleotide polymorphism (SNP) markers for the efficient utilization of these accessions. From the results, the SNP and DArT markers were well distributed across the 20 soybean chromosomes. The cluster and principal component analyses revealed the genetic diversity among the 281 accessions by grouping them into two stratifications, a grouping that was also evident from the population structure analysis, which divided the 281 accessions into two distinct groups. The analysis of molecular variance revealed that 97% and 98% of the genetic variances using SNP and DArT markers, respectively, were within the population. Genetic diversity indices such as Shannon's diversity index, diversity and unbiased diversity revealed the diversity among the different populations of the soybean accessions. The SNP and DArT markers used provided similar information on the structure, diversity and polymorphism of the accessions, which indicates the applicability of the DArT marker in genetic diversity studies. Our study provides information about the genetic structure and diversity of the IITA soybean accessions that will allow for the efficient utilization of these accessions in soybean improvement programs, especially in Africa.