SATrends Issue 26                                                                                                                   January 2003

Have you ever heard the expression “Don’t throw out the baby with the bath

  • Babies and Bath Water
  • The Multipurpose Mouse Killer
  • Scientists' Meet on Chickpea
  • Groundnut in West Africa
  • 1. Babies and Bath Water
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    Have you ever heard the expression “Don’t throw out the baby with the bath water”? In other words, in your enthusiasm to get rid of the unwanted, don’t harm what is useful. One of the latest catchwords today is “biotechnology”, which holds great promise for developing crop plants with resistance to pests. Development and deployment of insect-resistant transgenic crops, for example, will lead to a drastic reduction of insecticide sprays and insecticide residues in food. Decreasing insecticide use will also increase activity of other, non-target, natural enemies. But, lest we err beyond redemption, it is important to also study the effects of transgenic crops on non-target enemies.

    Genes from bacteria such as Bacillus thuringiensis (Bt) have been used successfully for pest control through transgenic crops on a commercial scale. However, transgenics are not a panacea for solving all pest problems, and they have their limitations.

    • Secondary pests may assume a major pest status.
    • Control of secondary pests will kill the natural enemies.
    • Proximity to sprayed fields and insect migration may reduce benefits of transgenics.
    • Development of resistance in insect populations may limit the usefulness of transgenics.

    Scientists have conducted many experiments to see the effects of transgenic crops on non-target predators, parasitoids, and also on flora and fauna in the rhizosphere. Long-term field studies with larger sample sizes, however, should be conducted to further characterize the effects of transgenic crops on natural enemies in the field.

    Insect pests are major constraints to increased production and productivity of ICRISAT mandate crops – sorghum, pearl millet, pigeonpea, chickpea and groundnut. The avoidable losses due to insect pests have been estimated at over US$ 14 billion annually. Therefore, there is a need to develop cost effective measures to minimize the pest-associated losses to stabilize crop production in the semi-arid tropics.

    In collaboration with the Swiss Federal Research Station for Agro-ecology and Agriculture (FAL), Zurich, Switzerland, and the Department of Biotechnology, India, ICRISAT has initiated studies on the effects of transgenic chickpea on the non-target natural enemies of Helicoverpa armigera, (right) which aims to:

    • Develop methods (laboratory, and semi-field) to test the impact of insecticidal proteins from genetically modified plants on selected beneficial insects (Campoletis chlorideae and Coccinella septempunctata - important natural enemies of Helicoverpa armigera and aphids).
    • Assess the impact of pure transgene products (Bt toxins, and garlic lectin) and transgenic chickpea plants on selected arthropod natural enemies when attacking pest insects containing the transgenic proteins.
    • The information generated through these studies will lead to a realistic assessment of transgenic chickpea for its effects on non-target natural enemies.

    For more information contact h.sharma@cgiar.org

    2. The Multipurpose Mouse Killer
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    Gliricidia sepium. The very name has a musical lilt that makes one want to wax lyrical about it. But the attraction doesn’t end with the name. Gliricidia is a fast-growing, tropical, leguminous tree that one scarcely notices. Yet it is ubiquitous. One passes it on highways and back roads. It is found in just about any patch of wild trees and bushes.

    The benefits of Gliricidia, a native of Central America, have been known for years. Although the tree was introduced into South India in the 1930s when it was grown as a shade tree in coffee and tea estates, Indian scientists only began to pay attention to it in the 1950s.

    What is so special about Gliricidia? The most obvious benefit is that it is a legume and thus useful for fixing nitrogen in the soil (about 30 kg/ha/year). Also, this adaptable tree can grow in a wide range of soils – acidic, sandy, heavy clay, calcareous limestone and alkaline.

    Interestingly, Gliricidia means mouse or rat killer. This part of the name is derived from its bark and leaves, which when cooked with grains can be used as poisonous bait for rodents. Though poisonous to rodents and insects, the leaves contain 3-4% dry weight of nitrogen (and small amounts of phosphorus, potassium, calcium and magnesium), so they can be used as excellent green manure and fodder for farmyard animals.

    At ICRISAT Gliricidia was part of an agroforestry project in the 1980s, but from 1996 onwards soil scientists began to draw the full benefits from this amazing tree. Its role in soil management is invaluable. Also, the roots stabilize sloping lands and reduce soil erosion. (Below right, spreading green manure)

    All farmers should be encouraged to grow Gliricidia on their farm bunds and borders of fields – not only would they be improving their soil quality, increasing crop yields and sequestering carbon for the organic matter hungry tropical soils, but the tree could also be used for timber, firewood, hedges, plantation shade and poles. Above all, propagating and sustaining Gliricidia is easy and inexpensive. Seed propagation is convenient for a large number of plants, but the tree re-sprouts quickly after pruning or even a fire, and the cuttings root very easily. No wonder they call it “quick stick” in Jamaica!

    For more information contact s.wani@cgiar.org

    3. Scientists' Meet on Chickpea
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    After winning the year 2002 King Baudouin Award for research on chickpea, the fraternity of scientists from ICRISAT and national research institutions gathered for the Second Biennial Chickpea Scientists’ Meet at Patancheru on 16 and 17 January.

    Organized jointly by the Indian Council of Agricultural Research and ICRISAT, 40 scientists from Indian research institutions participated. Also present were delegates from Bangladesh, Nepal, Pakistan, Ethiopia, Australia and Canada.

    The experts discussed developments in chickpea research and reviewed future trends. The visiting scientists selected breeding material and germplasm for field trials. At the same time, ICRISAT scientists were able to glean nuggets of wisdom from the visitors to help them tweak their research strategy.

    Because it can withstand considerable stress, chickpea can support farmers’ livelihoods in the rainfed tropics. It is also the most important leguminous food grain for the people of South Asia, providing dietary protein to vegetarians.

    Across the globe, 8.25 million tons of chickpea were produced in 2002 from 10.66 million hectares of farmland. India accounted for nearly 65% of the global cropped area.

    Although the area sown to chickpea area has not increased during the past two decades, yield has increased, resulting in a modest annual growth of 2%.

    Though originally a cool-season crop of the temperate latitudes, the development of short-duration, heat-tolerant varieties have moved this crop further south in the dry tropics. In South Asia the chickpea growing area has dramatically shifted. For instance, the growth of irrigated agriculture in the north has pushed the chickpea belt south into the peninsular region. In Andhra Pradesh, where once the crop was hardly grown at all, it has become a major crop.

    The most interesting trend, however, is that in some places farmers are shifting to chickpea cultivation from cash crops. For instance, in Andhra Pradesh, farmers debt-ridden from purchasing chemicals for their tobacco, chili and cotton crops are moving to chickpea. The result: a tenfold increase in production since 1986.

    An opportunity in South Asia is to bring large tracts of land lying fallow after rice harvest into chickpea cultivation. Encouraging results have come from Bangladesh where 10,000 hectares of rice fallow are now being used for chickpea.

    The challenge is to develop cultivars with improved water use efficiency and drought tolerance. This is especially important, because as water sources become increasingly scarce across the globe, the portion used for agriculture is dropping.

    For more information contact p.gaur@cgiar.org

    4. Groundnut in West Africa
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    If you are a groundnut farmer in West Africa then there is cause to cheer.  The recently completed Groundnut Germplasm Project has collected and identified the best germplasm for the crop.

    The Common Fund for Commodities funded the project, with scientific partnership from ICRISAT, Institut Senegalais de Reserches Agricole (ISRA) and the International Cooperation Centres for Agronomic Research for Development (CIRAD). The Governments of Nigeria, Niger, Burkina Faso and Mali implemented the project.

    Since the objective was to identify the germplasm with best economic traits, the first step was to assemble, maintain and conserve groundnut germplasm in these counties. Over 12,000 accessions were assembled and recorded. (Right, groundnut collection in Mali).

    This was followed by the preparation of a readily available description of assembled germplasm. In addition to distributing and exchanging the germplasm with the national agricultural research system of the project countries, a seed multiplication project was also carried out.

    It is one thing to collect germplasm, quite another to see how they perform in various locations. Multilocation evaluation of collected germplasm was carried out before they were identified and shortlisted for their economic importance.

    The genetic sources of economic importance were identified and characterized and information on them communicated to the national scientists. The promising genetic material was made available to the national research system for further testing.

    Groundnut productivity in West and Central Africa is limited by a number of biotic and abiotic constraints – foliar diseases, groundnut rosette virus, peanut clump virus, aflatoxin contamination and drought. The germplasm was therefore screened for sources of resistance to these biological stresses. It was also screened for edible groundnut characteristics such as pod and kernel size and threshing percentage.

    Promising drought-tolerant varieties developed by ICRISAT and CIRAD in collaboration with ISRA/CERRAS were used in regional testing nurseries. New lines that produce acceptable yields under drought stress have been identified.

    More than 40 varieties were identified that can be used to significantly increase groundnut yields in the region. These varieties were made available to the interested national research stations, and steps initiated for their multiplication.

    The initial responsibility of seed multiplication from breeder seed nuclei was given entirely to ISRA. This production was progressively decentralized to ICRISAT and the NARS to enable easy distribution in close proximity to users.

    To further disseminate the technical information, workshops were held for the groundnut business and academic community of the region. Newsletters, bulletins and catalogs were also used.

    For more information contact f.waliyar@cgiar.org.