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Apr 30, 2022Keywords:
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Main Article Content
Effects of Two Unrelated Viruses on Growth and Yield of Some Cowpea (Vigna unguiculata L. Walp.) Cultivars in Mokwa, Southern Guinea Savannah
Abstract
Twenty five cowpea cultivars were evaluated for their reaction to Blackeye cowpea mosaic virus (BICMV) and Cowpea mottle virus (CPMoV) singly and the mixture of BICMV + CPMoV under field conditions at Mokwa, Southern Guinea agro-ecological zone in the 2017 wet season. The trial was laid out using randomized complete block design with three replications. For the single virus inoculation, seedlings of the twenty five cultivars were mechanically inoculated singly with BICMV or CPMoV at 10 days after sowing, while for the mixed virus inoculation, cowpea seedlings were mechanically inoculated with double virus mixture; that is BICMV at 10 days after sowing (DAS) and CPMoV at 17 DAS. Symptom expression such as bright yellowing, mosaic and mottling started one week after inoculation (WAI) from all treatments, while at 2 WAI, 50.0–84.3 % infection was observed among the viruses and cowpea cultivars. The plants showed typical symptoms of both viruses but at varying levels. The rating done on a scale of 1 - 5 with respect to symptomatology indicated that the viruses had significant (p˂ 0.05) severe effects on the crops. The severity of the viruses on symptom rating indicated that BICMV caused the highest severity effects in Ife Brown, IT99K – 316 – 2 and IT07K – 211 – 1 - 8 which rated 4.3, CPMoV induced the highest severity effects in Ife brown, IT99K – 316 – 2 and IT06K – 137 – 1 with ratings of 4.3, while disease severity rating of the co-infections of BICMV + CPMoV did not differ from those of BICMV alone. However, BlCMV disease severity was significantly lowest (1.6) in cultivars IT97K-568-18 and IT03K-337-6. Cultivars IT90K-277-2, IT96D-610, IT99K-316-2, IT04K-267-8, IT04K-332-1 and IT07K-243-1-10 exhibited significantly low disease severity of 1.8 on CPMoV infection, while cultivars IT96D-610, IT97K-499-35, IT97K-573-2-1 and IT04K-332-1 show the lowest disease severity score of 1.6 in the mixed virus infections. Generally, cowpea cultivar IT07K-292-1-10 consistently gave significantly (p˂0.05) highest seed weight per plant irrespective of the virus treatments. The results indicate the potentials of cultivar IT07K-292-1-10 as source of resistance gene (s) for breeding cowpea against BICMV and CPMoV disease to enhance productivity and food security.
