SATrends Issue 77 April 2007
  • The "acid" test!
  • Food security fires hope
  • A presidential push for prosperity

  • 1. The "acid" test!
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    Abiotic stresses such as drought and salinity constitute major causes of yield loss in crops. But crops have remarkable strategies for tolerance within their genetic makeup. Understanding the physiological and genetic bases that underlie these adaptive strategies is vital for crop improvement towards sustainable agriculture under water-limited conditions.

    A regulatory component that plays an important role in many plant responses to drought is abscisic acid (ABA), a compound that is also involved in the regulation of many aspects of plant growth and development, including stomatal function. The more ABA in shoots the less stomatal conductance (leading to conservation of water, but also to limited capacity to fix carbon) and increase in root biomass. It is therefore important to understand the physiology of ABA regulation in response to water-stress to determine its role in improvement of drought tolerance.

    ICRISAT's high performance computer Dry-down experiment in cylinders to determine the ABA response under water-stress conditions in the groundnut varieties, TAG-24 (drought tolerant) and TMV-2 (drought susceptible).

    As a first step, a simple indirect competitive enzyme-linked immunosorbent assay (cELISA) was developed to accurately estimate ABA levels in plants. The test involves purification of the free ABA from fresh leaf tissue, followed by cELISA estimation, where the sample's free ABA and a known amount of ABA standard bound to the plate compete for binding with the known concentration of anti-ABA antibodies. Antibodies bound to free ABA are removed and the plate-bound antibody-ABA complexes are detected via a colorimetric reaction with an enzyme-labeled reporter antibody to provide an estimate of the original ABA concentration. This test can detect levels of ABA in samples as low as 5 picogram/ml. The estimated cost for each analysis is around US$ 2. The test is simple to perform, and is effective for routine and high-throughput analysis.

    The cELISA was validated by measuring ABA in groundnut varieties - TMV 2 (drought susceptible) and TAG 24 (drought tolerant), grown under progressive soil-drying treatments. ABA concentration at two-weeks after stress imposition was high in water-stressed TAG 24, and low in water-stressed TMV 2, compared to respective controls, indicating a difference in water use pattern between the two varieties, ie, TAG 24 had a more "conservative" mechanism to use water under drought conditions. It will be necessary to analyze many additional and diverse genotypes of various crops to fully understand the relationship between ABA and drought tolerance. The cELISA technique now allows us to undertake these studies.

    For more information contact v.vadez@cgiar.org or p.lavakumar@cgiar.org

    2. Food security fires hope
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    The impact of HIV and AIDS on agriculture has long been a source of concern and a topic of numerous studies. Infection rates continue to increase in southern Africa and other SAT regions. AIDS has a devastating impact on rural households, decreasing labor power, time and resources available for farming. Furthermore, the high mortality rates among the working generation change the demography and consequently the needs of the rural population.

    Most studies have focused on the effects of AIDS, generally concluding that as a result food insecurity increases. However, less attention has been directed at the reverse relationship - the ways in which food insecurity fuels the spread of HIV and AIDS. This is unfortunate, because improved awareness and understanding of the dynamics that facilitate the pandemic can reveal potential new areas for intervention.

    fertilizer to resource-poor farmers The vicious circle of food insecurity and AIDS.

    A new study among women smallholder farmers in Malawi aims to address the question of how agricultural development can increase the resilience and resistance of rural SAT women to HIV and AIDS. The study will use anthropological research methods to increase the understanding of the relationship between AIDS and food insecurity at the village level and assess the information adoption constraints among smallholder women farmers as well as their (changing) agricultural needs.

    Women are found to be increasingly infected with HIV; in southern Africa they constitute 58% of all those infected, and this proportion continues to rise. There appears to be several reasons for this unequal distribution - women are physically more susceptible to infection, their economic and socio-cultural dependence on men leads to male dominance within sexual relations, and poor women resort to transactional survival sex. Conventional AIDS interventions aimed at raising awareness have had little effect, arguably because underlying causes such as food insecurity and gender inequality inhibit people, especially poor women, to live up to the propagated behavior changes.

    More secure livelihoods for rural women could help prevent hazardous survival sex and exploitative power relations that increase their risk of becoming infected with and spreading HIV. Improved agricultural technologies can diminish rural food insecurity, and, if well targeted, diminish gender inequality. However, the uptake of agricultural information, just like the uptake of AIDS information, is generally low among poor rural women. To increase adoption levels, innovations need to be relevant and communication methods appropriate for the target group and within the specific context.

    For more information contact j.verheijen@malawi.net

    3. A presidential push for prosperity
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    The soils of the semi-arid tropics are generally marginal and highly degraded, so combating land degradation and increasing productivity here is a major challenge.

    Affordable and sustainable crop management options (nutrients, water management, crop-livestock, IPM, cultivar, rotations) developed and promoted in collaboration with NARES partners in Africa and Asia recently caught the attention of, and influenced policy makers in India, specifically the President of the Government of India, Dr APJ Abdul Kalam, and parliamentarians in Madhya Pradesh state of India.

    The ICRISAT-led consortium of community watersheds used characterization of soil resources in the benchmark watersheds of Madhya Pradesh and Rajasthan states in India as an entry point activity. Stratified sampling of fields revealed widespread deficiency of multiple nutrients particularly Zn (67-100 %), B (72-100 %) and S (72-100 %) along with N and P, which could be limiting the yield potential in the watersheds.

    ICRISAT's high performance computer A healthy soybean field managed with balanced nutrition.

    The President of India addressed elected representatives of the Madhya Pradesh Assembly in 2006 highlighting the outputs from the recently concluded Tata-ICRISAT-ICAR project to double the productivity of soybean in India based on project outputs in the area of integrated watershed management. This indicated that by adopting a holistic watershed improvement approach, the potential productivity of soybean could be increased by 100%. Overall systems productivity improvement with better water and integrated nutrient management options had resulted in a doubling of farmer income in the watersheds.

    The farmer participatory trials highlighted the urgency to provide the right information about soil health to the farmers in time, thus empowering them to adopt balanced nutrient management strategies for increasing productivity and minimizing cost of inputs.

    President Kalam charted out the path, based on ICRISAT's experience, on how to proceed in the future to achieve these ends. He indicated that ICRISAT should be able to provide the appropriate technical assistance, and that financial assistance can be provided by the National Bank for Agriculture and Research Development, bringing in private companies for post harvest processing. He indicated that through this approach the total revenue for farmers from soybean could be doubled and could potentially benefit up to 5 million farm families in the country.

    For more information contact s.cherukumalli@cgaiar.org or s.wani@cgiar.org