Department of Plant Science

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Department of Plant Science

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Browsing Department of Plant Science by Subject "Cowpea"

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    Artificial Defoliaton of Cowpea [Vigna unguiculata (L.) Walp.] cv. Ife Brown to Simulate Insect Damage: Effects on Crop Performance
    (Faculty of Agriculture, University of Ife, 1980) Akingbohungbe, A. E.
    The effects of defoliation on cowpea, Vigna unguiculata (L.) Walp cv. Ife Brown, were studied in the screenhouse by removing varying proportions of the laminae of leaflet along-the transverse plane, to give varying nominal levels of defoliation. Plants subjected once to 25%, SO%, 75% and 100% defoliation at either the primary leaf stage, the first trifoliate leaf stage or the second trifoliate leaf stage, were not adversely affected with respect to days to peak flowering, number of flowers per plant, number of pods per plant as well as number and weight of seeds per plant. However, 100% defoliation significantly delayed the days to first flower production. When plants were subjected to 25%, 50% and 75% nominal defoliation once a week for a period of three weeks, commencing at the first trifoliate leaf stage, significant treatment effects were observed with the 75% defoliation adversely affecting the number of pods per plant, number and weight of seeds per plant. I t was also observed that defoliated leaflets tended to compensate by increasing their widths. The importance of the results are discussed in relation to the impact of defoliators and recommendation's for their control in cowpea production.
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    A Note on the Heritability of Pod Length and Number of Seeds per Pod in Cowpea, Vigna unguiculata s.sp. unguicalata (L) Walp
    (Faculty of Agriculture, University of Ife, 1982) Ogunbodede, B. A.; Fatunla, T.
    KR 91, (a short podded cowpea cultivar) was crossed to Paraquay No. 2, (a long podded cultivar), while Victor (a crowder) was crossed with B33 (a non-crowder) to study the inheritance of pod length and seed number respectively in the two crosses. The two parents, PI, P2, and the progenies F1, BC1, BC2 and F2 of each cross were evaluated at the University of Ife Teaching and Research Farm. Narrow sense heritability estimates of 72.1% and 36.8% were obtained for pod length and number of seeds per pod respectively. About seven and eight pairs of genes control pod length and number of seeds per pod respectively.
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    Studies on Cowpea Varietal Resistance to the Cowpea Flower and Pod Borer, Maruca Testulalis (Geyer) (Lepidoptera Pyralidae).
    (Obafemi Awolowo University, 1985) Echendu, Thank-God Nnamdi; Akingbohungbe, A.E.
    Several varieties of cowpea, Vigna unguiculata s.sp. unguiculata (L,) Walp., were screened for resistance to the cowpea flower and pod borer, Maruca testulalis (Geyer) using free-choice field trials, cohort tests in large screened cages and no-choice tests in the screenhouse and the laboratory. The damage potential of M. testulalis on Ife Brown cowpea was also studied using controlled infestations in order to establish a baseline infestation level that could be used to differentiate resistance effectively in no choice tests. The study on the damage potential showed that successful establishment of the first in star larvae could only be obtained and sustained throughout the crop growth at the flower bud stage. At this stage, infested plants showed significantly reduced numbers of flowers and pods as well as seed yield. Two first in star larvae per plant was the lowest infestation that produced such significant differences between infested plants and the control. Thus, it is suggested as an adequate level for differentiating susceptible and resistant varieties in no choice tests employing Ife Brown as a standard. The free choice field trials showed significant differences in the degree of susceptibility of the varieties screened. Using overall susceptibility indices that considered some parameters associated with pest attack and which could affect flowering, podding and seed yield, TVu 1896 A/G, Sese, EW/1 and H64-3 were found to be moderately resistant to flower damage; while 2Ak and TVu 1896 A/G were shown to be moderately resistant to pod and seed damage. The field resistance was confirmed by the cohort and no-choice tests. TVu 1896 A/G and H51-1 were found to be resistant to pod and seed damage while TVu 946 and 2Ak were moderately resistant. Non-preference for oviposition and larval feeding appeared responsible for the resistance observed. Antibiosis manifested in form of reduced weight and size, and lengthened pupal period was also observed.