Bambara groundnut (Vigna subterranean L. Verdc) is a leguminous plant and its seeds are highly nutritious and can be considered as complete food. In addition to being a neglected crop; its production is limited by several constraints among which virus diseases are the most implicated. In order to contribute to the improvement of bambara groundnut in Nigeria, landraces of bambara groundnut were screened for resistance to Cucumber mosaic virus (CMV), one of the most damaging viruses in grain legumes. Treatments consisted of five landraces namely Black, Brown, Cream, Red nav, and Zebra coloured got from local farmers. These were arranged in Randomised Complete Block Design, with three replicates. Seedlings were infected with CMV isolate three weeks after sowing (WAS), during the 2019 and 2020 trials. The infected plants exhibited various symptoms of chlorosis, leaf deformation, growth retardation, and plant stunting. The sCMV caused significant reduction in plant height, the number of branches, leaves, pods, and seeds weight. In the 2019 and 2020 trials, 100 % incidence with the highest severity was observed in the Bambara groundnut landraces. Disease incidence varied between 41.6% in “Black” and 95.8 % in “Cream,” while disease severity was higher in “Cream” and “Red nav” with 5.0 respectively. “Black” and “Zebra” were the tallest with 16.8 cm among the infected as well as disease-free with 22.6 cm tall plants. “Black” landrace produced the highest number of pods in both CMV infections with 21 and disease-free with 33 pods respectively. Conversely, the number of days to flowering of 43 days was highest in infected plants of “Black”. The “Black” and “Zebra” landraces recorded uniform seed weights and the highest seed weight under CMV infection with 1.7 g per plant. The impact of the virus on yield loss was lowest in “Black” and “Zebra” landraces which indicated their possible use in the management of Cucumber mosaic virus disease in Bambara groundnut.

properties of soil on the incidence and infestation of plant-parasitic nematodes on Pepper, Capsicum spp from two local government areas (LGAs) of Niger State, Nigeria. One hundred and twenty soil and plant root samples were randomly collected from pepper fields and examined. Results showed that six genera of plant-parasitic nematodes were recorded. The most frequently observed and widely distributed nematode species were Helicotylenchus multicinctum followed by Meloidogyne spp. and Scutellonema bradys with frequencies of occurrence of 48.2, 34.8 and 12.6 % respectively. Highest nematodes population density of 405 in 100 ml soil was recorded from Maje followed by Annaba with 205, both in Magama LGA, while the lowest nematodes of 20 in 100ml soil were recorded from Nagwamatse in Kontagora LGA. Correlation analysis revealed a weak relationship between soil physico-chemical properties and nematode population density with maximum value of r = 0.38. The results also showed that apart from the direct influence of the host plant, soil properties play an important role in the distribution, abundance, and structure of plant parasitic nematode communities. This demonstrates the potential of nematodes as bio-indicator organisms of soil health.

Field surveys were conducted during the 2015 cropping season to identify and determine the distribution of legume viruses in Niger State, Nigeria. A total of 27 locations were visited during the surveys. Leaves were collected from weed plants showing virus and virus-like symptoms in fields of cowpeas, groundnuts and soyabean. Samples were also collected from asymptomatic plants within the vicinity of infected plants. The antigen coated plate - enzyme linked immunosorbent assay (ACP –ELISA) method was employed for virus detection in the collected leaf samples. Results showed that Blackeye cowpea mosaic virus (BICMV), Cowpea mild mottle virus (CPMMV) and Cowpea mottle virus (CPMoV) were the viruses detected. Thus Aeschynomene indica, Amaranthus caudatum and Centrosema pubescens were positive to BICMV; while Aspilia africana, Cleome viscera, Euphorbia hirta and Heterotis rotundifolia were hosts of CPMoV and CPMMV was detected in Chenopodium amaranticolor, Desmodium scorpiurus, and Vicia faba. The detection of these viruses in weed species in the surveyed areas indicates their importance in the ecology, survival and the significant role they play in the epiphytology of the various virus diseases. The occurrence of BICMV, CPMoV and CPMMV in these weed species is believed to be the first report in the study area.

Cowpea being a dependable source of protein for human growth and development is widely cultivated in sub-Saharan Africa including Nigeria. In spite of its numerous uses, infection by viruses constitutes serious problems to its productivity and once plants are infected, there is no remedy as is with other pathogens such as bacteria, fungi and nematodes. A field trial was conducted to investigate the reactions of twenty five cowpea cultivars to single and mixed infections with two unrelated viruses: Blackeye cowpea mosaic virus (BlCMV) and Cowpea mottle virus (CPMoV) on seed germination and longevity. The trial was conducted at the Teaching and Research Farm of the Ahmadu Bello University (ABU), Zaria, Mokwa Station and set up in a randomized complete block design (RCBD) with three replicates. For the single virus infection, seedlings of the twenty five cultivars were inoculated at 10 days after sowing (DAS), while for the mixed virus infections, seedlings were inoculated at 10 and 17 DAS. Results showed that all the cultivars were susceptible to single and mixed infections but to seemingly different extents. Germination of seeds was generally high before storage but was short lived indicating that conservation of infected seeds of the cultivars was impaired. Seeds of cultivars IT04K-267-8 and IT07K-222-2 recorded germination percentages of 54.6 and 53.7% respectively, while cultivars IT96D-610 and IT04K-291-2 had germination values of 52% which did not differ from each other. Viability of seeds amongst the 25 test cowpea cultivars from single infection with CPMoV alone and BICMV alone did not differ in some instances. Percent germination in cultivars IT98K-205-M8, IT90K-277-2 and IT07K-222-2 inoculated with BICMV + CPMoV were not much affected. Test of accelerated ageing germination (AAG) percentage for four weeks showed that seed vigour was greatly impaired in cultivars IT07K-292-2-10, IT06K-124 and IT90K-277-2 infected with BICMV + CPMoV compared to the lowest AAG percentage of 31.6 recorded in seeds of cultivar IT99K-377-1. Constant monitoring of legume fields through regular field sanitation and disease surveys to identify new and emerging viruses as facts obtained from this study are good starting point for legume virus diseases diagnosis.

Soyabean is an important source of protein for millions of people in developing countries. However, infection by Cucumber mosaic virus (CMV) causes devastating losses. Cultivation of resistant varieties has been identified as the best management strategy in many crops. The present study was, therefore, conducted to identify soyabean genotypes with high stability for growth and seed weight under CMV and disease-free conditions. Thus, eight soyabean genotypes were evaluated as CMV-infected and uninfected, using completely randomised design replicated five times and set up in the screenhouse at the School of Agriculture and Agricultural Technology, Federal University of Minna, (lat.9°40֬ N;long 6°30֬ E at an altitude of 220 m.a.s.l), Nigeria in 2018. Soyabean seedlings were infected with the virus by sap transmission at 10 days after sowing (DAS). Additive Main Effects and Multiplicative (AMMI) analyses of the evaluated parameters for growth and seed weight of the test genotypes showed that environments’ effects -infected and uninfected- were significant (p<0.05). They accounted for 100% Genotype × Environment (G×E) interaction. Disease-free soyabean plants enhanced significantly higher growth and seed weight than the CMV-infected plants. The AMMI and Genotype main effects (G) plus Genotype×Environment (GGE) analyses showed that TGX 1993-4FN was the genotype with the greatest stability for leaf diameter, leaf length, number of leaves per plant, number of days to flowering and seed weight. It is recommended that, the soyabean genotype TGX 1993-4FN, can be exploited for breeding purposes and strategies that will prevent CMV infection in soyabean fields should so be adopted by farmers.