Yam is an important tuber crop nutritionally, socio-culturally, and an income generator for many Nigerian. This explains its high demand both locally and internationally, causing increased production as Nigeria leads world production with about 45.41 million metric tons annually. The peculiarity of yam production in Nigeria entails lower yield, high cost of production, and post-harvest losses. Yam produced in Nigeria falls far below the potential crop yield, therefore, it is essential to close these yield gaps through the provision of solutions to the different constraints that hamper sustainable yam production. Despite the challenges, there is still insufficient information on the impact of policies, weeds, pests, and diseases which constitute major constraints. Nigerian farmers mostly utilize indigenous cultural approaches to manage yam production. Their goal of production is to produce yam cultivars that are suitable mainly for food products leading to the neglect of other cultivars. Few selected institutions with a yam mandate have been working on improving the production of D. rotundata and D. alata through breeding yam cultivars suitable for consumption and resilient against pests and diseases. However, more extensive studies should focus on breeding programs for yam resilient under drought and flooding, with peculiar physicochemical properties that give unique textual qualities considered in pounded yam and other yam food products. In this review paper, the significance and limitations of yam production in Nigeria and her efforts to achieve sustainable production are extensively studied.

Maize is an important cereal crop widely grown in all of Nigeria’s agroecology based on its economic and food values. This has led to its optimum production with Nigeria ranking top 12th maize producer in the world. Presently, the fall armyworm (FAW), Spodoptera frugiperda is considered a potential threat to food security in Nigeria due to its devastating feeding pattern on maize and its wide host range. Its invasive and high dispersal nature enhances its spread from its first reported state (Oyo) in early 2016 to the entire 36 states of Nigeria by the year 2018. It accounts for averagely an estimated 34% or more yield reduction in Nigeria’s maize field, hence, a need for an efficient management approach. Although most farmers rely on the use of insecticide, it is found ineffective because of the inaccessible location of FAW in maize. This study was carried out to investigate the different management approaches adopted in Nigeria to control FAW and its impact on the insect pest population. Conventional measures such as planting improved seeds, avoidance of late planting, and polyculture to increase the natural enemy’s population have been used but with limited control of FAW. Maize lines with aflatoxin resistance or transgenic Bt-maize are found resistant to FAW. Botanicals such as neem extract lowered the percentage of leaf area damage, incidence of FAW larva infestation, and the number of larvae. It is difficult to curtail the menace of FAW through one control method, hence, the need for an integrated approach

Soybean is an important crop widely grown in the northern region of Nigeria for human and animal consumption. Commercial production of soybean in Nigeria has existed for eight decades. Current malnutrition and nutrient health problems in Nigeria warranted the introduction of high nutritive and affordable food sources such as soybean in the Nigerian diet. The high demand for soybean and its products has led to the rise in the cultivation of soybean in Nigeria. Although an increase in production has been recorded, the region of production has failed to achieve the potential yield per hectare. In improving soybean production in Nigeria, it is paramount to understand the factors that contribute to the process of production. This review paper provides information on factors affecting soybean production across the regions of production in Nigeria. The identified factors responsible for the yield gap include the impact of climate change on the agroecology shift, nutrient depletion and soil fertility, sowing date, the emergence of pests and diseases, and limited improved soybean cultivars. Adoption of improved soybean variety suitable in agroecology and sowing, at the appropriate sowing date by Nigerian farmers, can guarantee optimum soybean production. Further soybean breeding improvement studies are needed to provide more improved varieties with superior performance in Nigeria’s agroecology to achieve yield potential.

Development and fecundity of the foxglove aphid, Aulacorthum solani (Hemiptera: Aphididae) were investigated at ten constant temperatures (photoperiod: 15L:9D) from 2.5 to 30℃ on soybean (Glycine max) leaves. The nymphs couldn’t emerge to adults at 2.5 and 30℃. The lower development temperature threshold and thermal constant of development completion estimated with a linear development model in nymph were 5.02℃ and 131.2 degree-days. The lethal temperatures were estimated as 33.9 and 32.5℃ with Lactin 2 and Logan 6 non-linear models, respectively. Mean generation time (from 78.4 to 11.8 d) decreased with increasing temperatures (from 7.5 to 27.5℃). The highest net reproductive rate (77.4) was observed at 20℃. The highest intrinsic rates of population increase (0.282) and shortest population doubling times (2.07 d) were recorded at 25℃.

Foxglove aphid, Aulacorthum solani (Kaltenbach), is a Hemipteran insect that infected a wide variety of plants worldwide and caused serious yield losses in crops. The objective of this study was to identify the putative QTL for foxglove aphid resistance in wild soybean, PI 366121, (Glycine soja Sieb. and Zucc.). One hundred and forty one F2-derived F8 recombinant inbred lines developed from a cross of susceptible Williams 82 and resistant PI 366121, were used. The phenotyping of antibiosis and antixenosis was done through choice and no-choice assays with total plant damage (TPD) and primary infestation leaf damage (PLD); a genome-wide molecular linkage map was constructed with 504 single nucleotide polymorphism markers utilizing a GoldenGate assay. Using inclusive composite interval mapping analysis for foxglove aphid resistance, one major candidate QTL on chromosome 7 and 3 minor QTL regions on chromosome 3, 6 and 18 were identified. The major QTL on chromosome 7 showed both antixenosis and antibiosis resistance responses. However, the minor QTLs showed only antixenosis resistance response. The major QTL mapped to a different chromosome than the previously identified foxglove aphid resistance QTL, Raso1, from the cultivar Adams. Also, the responses to the Korea biotype foxglove aphid were different for Raso1, and the gene from PI 366121 against the Korea biotype foxglove aphid were different. Thus the foxglove aphid resistance gene from PI 366121 was determined to be an independent gene to Raso1 and designated to Raso2. This result could be useful in breeding for new foxglove aphid resistant soybean cultivars.

Foxglove aphid, Aulacorthum solani (Kaltenbach), is a Hemipteran insect that infected a wide variety of plants worldwide and caused serious yield losses in crops. The foxglove aphid resistance gene, Raso2 was previously mapped from PI 366121 (Glycine soja Sieb. and Zucc.) to a 26cM marker interval on soybean chromosome 7. The development of additional genetic markers, which are mapped closer to Raso2 were required to accurately position the gene to improve the effectiveness of marker assisted selection. The objective of this study was to narrow down the putative QTL region, which is responsible to foxglove aphid resistance in PI366121 using recently developed high-density 180K Axiom SoyaSNP genotyping array. One hundred and forty one F8-derived F12 recombinant inbred lines developed from a cross of susceptible Williams 82 and resistant PI 366121, were used to generate a fine map of Raso2 interval. The phenotyping of antibiosis and antixenosis was done through choice and no-choice assays with total plant damage (TPD) and primary infestation leaf damage (PLD). The composite interval mapping analysis showed that the physical interval between two flanking makers, which was corresponding to Raso2, was narrowed down to 500kb on the Williams 82 genome assembly (Glyma2.0), instead of 4Mb in the previous report using Goldengate assay. In the Raso2 interval, there are about 60 candidate genes, including 4 of NBS-containing putative R genes. This result could be useful in breeding for new foxglove aphid resistant soybean cultivars.

The depletion of stratospheric ozone has resulted in increased amount of ultraviolet-B radiation (UV-B: 280-320 nm) reaching the Earth’s surface and could cause significant biological effect in plants. In this study, putative quantitative trait loci (QTL), which is responsible to UV-B resistance in soybean, was identified using recently developed high-density 180K Axiom SoyaSNP genotyping array. A population of 115 recombinant inbred lines (RILs) derived from a cross between susceptible Keunolkong and resistant Iksan 10 was analyzed. A total 8,970 polymorphic SNP markers were used to construct linkage map. The both parents and RILs were grown with supplemental UV-B radiation in a greenhouse condition. Three categories of UV-B induced morphological damage, degree of leaf chlorosis, leaf shape change, and total plant damage were evaluated. Using composite interval mapping analysis, one major QTL associated with all of the phenotypic traits was detected on 7.7cM of soybean chromosome 7 with 22 of LOD score accounting for about 60% of phenotypic variance. Also, the allele from Iksan 10 were responsible for the UV-B resistance. Thus, the UV-B resistance QTL on chromosome 7 from Iksan 10 was designated to qUVBR1, corresponding to 30kb on the Williams 82 genome assembly (Glyma2.0) including 7 candidate genes. This result could be useful in breeding for new foxglove aphid resistant soybean cultivars. In addition, these results provided useful information not only for marker-assisted selection for UV-B resistance soybean, but also for the future identification of putative candidate genes, responsible for UV-B resistance in soybean.