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Tough Pod Wall: A Factor Involved in Cowpea Resistance to Pod Sucking Bugs

  • H. S. Chiang
  • L. E. N. Jackai
Research Article

Abstract

Six cowpea cultivars, TVu 1890, TVu 1, TVx 3343-03E, IT82E-9, VITA-3 and Ife Brown, with different responses to infestation and damage by pod-sucking bugs (PSBs) were studied for the biophysical and biochemical characteristics of pod that may be involved in this differential response to feeding by PSBs. Tough pod wall, requiring a force of 25 newtons/mm2 to penetrate at pod maturity, is considered to be an important factor contributing to the lesser PSB feeding damage observed in the cultivar TVu 1890. The phenolic content of the pods of the studied cowpea cultivars was not correlated with their tannin content. Furthermore, no correlation could be established between the tannin content in the pod and the level of susceptibility of the cowpea cultivars to infestation and damage by PSBs. While tannins are considered to be important in conferring certain types of anti-herbivory properties to a number of plants and crop varieties, our findings suggest that in the cowpea cultivars studied, phenols in addition to the tough pod wall may be more important in conferring resistance to PSBs.

Résumé

Six cultivars de niébé, TVu 1890, TVu 1, TVx 3343-03E, IT82E-9, VITA-3 et Ife Brown, ayant différentes réponses à l’infestation et aux dégâts des punaises nuisibles (PSBs), ont fait l’objet d’une étude visant à évaluer les caractéristiques biophysiques et biochimiques des gousses probablement à l’origine de cette diversité de réactions aux PSBs. La dureté de la paroi des gousses est considérée comme un important facteur contribuant à la réduction des dégâts observés sur le cultivar TVu 1890, dans la mesure où la pénétration de cette paroi au stade de maturité des gousses requiert une force de 25 newtons/mm2. Les cultivars étudiés n’ont révélé aucune corrélation entre le phénol et le tanin contenus dans les gousses. Aucune corrélation n’a non plus été établie entre le tanin contenu dans les gousses et le niveau de sensibilité des cultivars de niébé aux dégâts des PSBs. S’il est vrai que les tanins confèrent certains types de propriétés anti-herbivores à plusieurs plantes et de variétés culturales, nos découvertes nous font supposer que dans les cultivars de niébé étudiés, une combinaison des phénols et de la dureté des parois des gousses contribuent davantage à la résistance aux PSBs.

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Copyright information

© ICIPE 1988

Authors and Affiliations

  • H. S. Chiang
    • 1
  • L. E. N. Jackai
    • 1
  1. 1.International Institute of Tropical AgricultureIbadanNigeria

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