, Volume 132, Issue 1, pp 7–22 | Cite as

Classification of cassava into ‘bitter’ and ‘cool’ in Malawi: From farmers' perception to characterisation by molecular markers

  • Jonathan Mkumbira
  • Linley Chiwona-Karltun
  • Ulf Lagercrantz
  • Nzola Meso Mahungu
  • John Saka
  • Albert Mhone
  • Mpoko Bokanga
  • Leon Brimer
  • Urban Gullberg
  • Hans Rosling


Cassava roots, a major food in Africa, contain cyanogenic glucosides that may cause toxic effects. Malawian women farmers considered fields of seemingly similar cassava plants to be mixes of both ‘cool’ and ‘bitter’ cultivars. They regard roots from ‘cool’ cultivars as non-toxic. Roots of ‘bitter’ were considered to require extensive traditional processing done by women to be safe for consumption. But curiously, these women farmers preferred ‘bitter’ cultivars since toxicity confers protection against theft, which was a serious threat to the food security of their families. We studied how well these farmers comprehend the effects of genetic variations in cassava when dealing with cyanogenesis in this complex system. Using molecular markers we show that most plants farmers identified as belonging to a particular named cultivar had a genotype typical of that cultivar. Farmers' ethno-classification into ‘cool’ and ‘bitter’ cultivars corresponded to a genetic sub-division of the typical genotypes of the most common cultivars, with four-fold higher cyanogenic glucoside levels in the bitter cultivars. Examining morphology, farmers distinguished genotypes better than did the investigators when using a standard botanical key. Undoubtedly, these women farmers grasp sufficiently the genetic diversity of cassava with regard to cyanogenesis to simultaneously benefit from it and avoid its dangers. Consequently, acyanogenic cassava – the breeding of which is an announced good of some cassava genetic improvement programmes – is not a priority to these farmers. Advances in molecular genetics can help improve food supply in Africa by rapid micropropagation, marker assisted breeding and introduction of transgenic varieties, but can also help to elucidate tropical small-scale farmers' needs and skills.

cassava cultivars cyanogenic glucosides molecular markers farmers'perception genotype Manihot esculenta 


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Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  • Jonathan Mkumbira
    • 1
    • 2
  • Linley Chiwona-Karltun
    • 3
    • 4
  • Ulf Lagercrantz
    • 2
  • Nzola Meso Mahungu
    • 5
  • John Saka
    • 6
  • Albert Mhone
    • 5
  • Mpoko Bokanga
    • 7
  • Leon Brimer
    • 8
  • Urban Gullberg
    • 2
  • Hans Rosling
    • 3
  1. 1.Bvumbwe Agricultural Research StationLimbeMalawi
  2. 2.Department of Plant BiologySwedish University of Agricultural SciencesUppsalaSweden
  3. 3.Division of International Health, Department of Public Health SciencesKarolinska InstituteStockholmSweden
  4. 4.Nutrition Unit, Department of Medical SciencesUppsala UniversityUppsalaSweden
  5. 5.IITA/SARRNET, Chitedze Research StationLilongweMalawi
  6. 6.Department of Chemistry, Chancellor CollegeUniversity of MalawiZombaMalawi
  7. 7.International Institute for Tropical AgricultureIbadanNigeria
  8. 8.Department of Pharmacology and PathobiologyThe Royal Veterinary and Agricultural UniversityFrederiksberg C.Denmark

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