SATrends Issue 73 December 2006
  • Micronutrients against malnutrition
  • Strangulating the Striga scourge
  • Great in theory, not so good in practice

  • 1. Micronutrients against malnutrition
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    The human cost of malnutrition in the Savannah zone of West Africa is devastating. In Mali for example, 39% of children under five are stunted, and 88% are anemic, with iron (Fe) deficiency as the most probable cause. Likewise, severe zinc deficiency causes short stature, impaired immune function and hinders the sense of taste and smell, with children's apathy to eat further compounding the problem. Sadly the situation is similar across the region. Furthermore, micronutrient deficiencies may even be increasing in the sorghum/millet zones of West Africa with population doubling every 30 years and with decreasing access to the best source of bio-available iron - meat.


    Guinea-race sorghum is a staple in Mali

    Sorghum and pearl millet provide the main staple foods for over 100 million people living in the semi-arid tropics of West and Central Africa. These crops are also an important source of micronutrients in this region, providing one third to one half of Fe/cap/day. Fortunately, genetic variability has been observed in adapted sorghum and millet varieties for grain quality, with over two-fold differences in iron and zinc contents being observed. Exploiting this genetic variability for key grain characteristics is one key approach to improving the nutritional value of these staple cereals.

    A team of research and development institutions (IER, INRAN, University of Hohenheim, German Agro Action, and Wageningen University) and farmers' organizations (ULPC, AOPP, Mooriben, Fuma Gaskiya) are actively working with ICRISAT in Mali and Niger to improve sorghum and pearl millet productivity through participatory breeding. Study of mineral contents of sorghum and millet has been initiated at ICRISAT through the HarvestPlus project. Additional efforts supported by the McKnight Foundation complement these studies with nutritional assessments at the household level and development of methodologies for incorporating nutrition into variety development programs.

    This team has just been further strengthened with the arrival at ICRISAT-Mali of Marjolein Smit, Associate Professional Officer- Human Nutrition. Marjolein has a Masters Degree in Nutrition and Health from Wageningen University with specialization in dietary behavior, disease prevention, and emphasis on food and nutrition security.

    Marjolein Smit will help in conducting studies on options for improving child nutrition in the Sahelian and Sudanian zones in WCA. These studies will include assessment of g rain traits of potential importance for retention of minerals during the decortication process. Major emphasis will also be given to village level assessments of methods of grain processing, food preparation, and feeding and dietary practices.

    For more information contact f.rattunde@CGIAR.ORG
    2. Strangulating the Striga scourge
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    Striga hermonthica (Del.) Benth., a parasitic weed, is a major biotic constraint to sorghum production particularly in the semi-arid regions of Africa. During droughts, it causes up to 100% yield losses. Over the last 10 years, ICRISAT and the University of Hohenheim have made significant progress in identifying molecular markers for Striga resistance in sorghum. During this period, five genomic regions (Quantitative Trail Loci or QTL) associated with stable Striga resistance from resistant line N13 were identified across a range of 10 field trials in Mali and Kenya. The resistance conferred is expected to be broad and durable.


    The pretty-looking Striga is the scourge of sorghum farmers.

    Flanking simple sequence repeats (SSR) markers to the QTLs in marker-assisted backcrossing is vital in transferring Striga resistance from the donor N13 to susceptible farmer preferred sorghum varieties (FPSVs). Through the project entitled Arresting the scourge of Striga on sorghum in Africa by combining the strengths of marker-assisted backcrossing and farmer-participatory selection , which is a three-year initiative funded by the BMZ, near-isogenic FPSVs will be developed carrying one to three Striga resistance QTLs. 

    Simultaneously, studies are undertaken to enhance the understanding of sorghum seed supply systems and to ensure the effective integration of seven Striga -resistant FPSVs into farming systems in Eritrea, Kenya, Mali and Sudan.  The extent of outcrossing rates and gene flow are being determined in five selected FPSVs.

    So far, 712 plants were genotyped from two backcross generations (BC 2 F 1 ) at the BecA research platform (ILRI Campus) using a total of 10 foreground SSR markers and 16 background SSR markers. Genotyping revealed that 256 plants from the second backcross generation (BC 2 F 1 ) were heterozygous for 1 to 3 QTLs.

    In Kenya, 43 BC 2 F 1 plants were selfed and genotyped to select for segregating homozygous BC 2 S 1 plants that have been taken through another selfing generation (BC 2 S 2 ) to fix the QTLs. Plans are now underway to genotype the BC 2 S 2 plants, and those confirmed to contain one to three QTLs will then be multiplied and evaluated for Striga resistance in artificially infested fields.

    In Mali and Sudan, genotyping of the BC 2 S 1 will be followed by selfing to fix the QTLs. Preliminary studies have revealed some variability in FPSVs with outcrossing rates ranging between 3 and 5%. Initial gene flow studies have shown pollen dispersal for distances of up to 100 m in multiple directions, with a marked decrease after 40 m from the center.

    For more information contact d.kiambi@cgiar.org

    3. Great in theory, not so good in practice
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    Some ideas can be great in theory, but not so in practice. A recent ICRISAT and University of Zimbabwe (UZ) survey shows that drip irrigation is one of these. Drip irrigation has the potential to significantly impact crop production. Fitting a field with a drum that stores water, a filter, and meters of pipes releasing water directly to the roots can, in theory, save a farmer significant amounts of labor, water and time.

    Given these potential advantages, drip irrigation kits were believed to be an important piece of the solution in addressing the challenges of HIV/AIDS and drought that farmers routinely face in eastern and southern Africa. Since 2001 NGOs have distributed around 70,000 drip irrigation kits to farmers in Zimbabwe. Each kit costs between 15 and 25 USD. Add distribution costs and staff time, and you have made a significant investment.

    The ICRISAT and UZ surveyed how well these drip kits faired in practice. Did this technology actually help the most vulnerable households? The survey liaised with seven NGOs who had distributed drip kits and also followed up with around 400 farmers in 14 districts in Zimbabwe.


    Lifting and pouring water into elevated drums is a labor-intensive task, making farmers reluctant to continue using drip kits.

    The results revealed that drip kits failed to have a significant impact on improving livelihoods and nutrition. In fact, most farmers failed to use the kits for more than one or two seasons. Their reasons for this included a lack of support in terms of advice and spare parts and, in many cases, a shortage of water forcing families to walk 12 km to the nearest boreholes. They also had to lift and pour the water into elevated drums a chore that many viewed as extremely labor intensive.

    The study also showed that many farmers misunderstood the concept of drip irrigation. Since the tubes deliver water directly to the roots, the surface of the soil remains dry. Many farmers wrongly interpreted this as a need for additional water or believed their drip kits were not functioning properly.

    The survey concluded that while drip irrigation has its advantages, using it in the context of relief work is unsuitable. Providing farmers with sound advice on crop, soil and water management, and support in terms of high-quality seed and other inputs, has a much more immediate and significant impact on nutrition and income. Perhaps drip irrigation will find a place in long-term development strategies. But, for now, the technology has not been able to successfully cross the divide between theory and practice.

    For more information contact p.belder@cgiar.org