SATrends Issue 81 August 2007
  • Pearl size on upward trajectory
  • High hopes with hybrids
  • Gaining and growing with groundnut
  • 1. Pearl size on upward trajectory
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    Traditionally, pearl millet [Pennisetum glaucum (L.) R. Br.] is a small-seeded crop, a trait associated with its adaptation to the arid environments in which its progenitors evolved. However, seed size is an important yield component and a farmer-preferred trait.

    Breeding for large grain size is one of the objectives of pearl millet research at ICRISAT. The first ICRISAT-bred open-pollinated variety (OPV), WC-C75, released in 1982, had a 1000-grain weight of 8-9 g, more than the most widely cultivated hybrid, BJ 104 (6-7 g 1000-1). Then came commercial hybrids produced on male-sterile line 843A, which is based on an ICRISAT reselection of KS 79-2068B from Kansas State University, with a 1000-grain weight of 8-10 g.

    The search for large-seeded genotypes continued. Screening of germplasm at ICRISAT revealed accessions with 1000-grain weight of 19-20 g, most of which were from the Iniadi landrace of the Togo - Ghana - Burkina Faso - Benin region of Africa. It was now possible to develop breeding lines, OPVs and hybrid parental lines with 1000-grain weight of >18 g.

    Progress in breeding for grain size

    At ICRISAT, considerable progress has been made to introgress this trait in hybrid seed parent lines and early generation progenies. As a result, male-sterile line 863A, derived directly from Iniadi germplasm, was released in 1986 with 1000-seed weight of 11-12 g. Subsequently, many commercial hybrids and OPVs were released with 1000-grain weight of 10-12 g. ICTP 8203, the earliest-maturing commercial open-pollinated pearl millet variety released in 1988 in India, was developed by recombining five progenies selected from a landrace of Togo with >12 g of 1000-grain weight. The grain size of ICTP 8203 was at least 50% higher than any open-pollinated cultivar previously released in India.

    Thus, the success of the Iniadi lines led to intensive germplasm evaluation and constitution at ICRISAT of the Bold-seeded early composite (BSEC) seeds with large globular seeds weighing 13 g per 1000 grains; and ICMP 94001, an Extra-early-maturing and nearly daylength-insensitive maintainer (B) Composite (EEBC) with 1000-grain weight of 14 g.

    An effort to introgress large seed size into well-adapted elite genetic backgrounds continues at ICRISAT and presently advanced seed parental lines with seed weight of >16 g per 1000 grains are available. Most of these lines have a soft endosperm. Research is underway to increase starch granules in bold-seeded lines to bring in grain-hardiness, which in turn, will further increase grain weight. The possibility of having elite lines with 1000-grain weight of more than 20 g now looks promising.

    For further information, contact r.bhattacharjee@cgiar.org

    2. High hopes with hybrids
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    If the goal is increased yield, more uniformity, or better resistance to environmental stresses, hybrids may be the way to go. Resulting from the pollination of very carefully chosen parents, hybrids often exhibit characteristics that are superior to either parent. A four-year study of the performance of sorghum hybrids in eight Southern Africa Development Community (SADC) countries shows that hybrids have a greater potential to increase productivity and impact farmers' livelihoods than open-pollinated varieties (OPVs).

    Hybrids displayed a yield advantage of 20-60% when compared to improved OPVs and local landraces. Across the four years and eight study countries, the average sorghum yields for hybrids were consistently higher than those for OPVs by more than 0.6t/ha. While not so different in years with favorable growing conditions, hybrids significantly outperform OPVs in dry years. For example, in 2001, hybrids yielded 3.8 t/ha whereas varieties produced 2.9t/ha - a yield difference of 0.9 t/ha. However, in 2002, a dry year, hybrids yielded 2.5t/ha and varieties produced 1.3 t/ha - a yield difference of 1.2 t/ha. These characteristics of hybrids increase their importance in dry areas and are a potential strategy to mitigate the effects of climate variability.

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    Dr Elijah Mwenge, ICRISAT scientist in Nairobi, shows the difference in yield between a hybrid (on his right) and an OPV.

    Hybrids are also able to compensate for missing plants better than OPVs. If a plant dies as a result of a pest attack, its hybrid neighbor will then utilize the available moisture more efficiently and carry a larger head, canceling out some of the effect of the reduced yield. Some other advantages of hybrids include early flowering and greater uniformity.

    However, despite this demonstrated potential, only a few sorghum hybrids have been released. In the eight study countries (Angola, Botswana, Malawi, Mozambique, Namibia, Tanzania, Zambia and Zimbabwe) 27 OPVs have been released as compared to only six hybrids that were released in the three countries of Botswana, Zambia and Zimbabwe. Farmers interested in growing hybrids have to buy seed each season and must have the economic motivation to do so. To increase cultivation and adoption of hybrids, inadequacies in the seed systems must be addressed and functional markets should be closely linked with industry. This will help create an environment where hybrids will take the position they deserve in enhancing crop productivity and profitability for improved livelihoods.

    For further information, contact m.mgonja@cgiar.org.

    3. Gaining and growing with groundnut
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    Shabila Musa belongs to Mpeta village, Chingutwa Ward, Masasi District in southern Tanzania. Groundnuts, the second most important smallholder crop after cashewnut in the district, and grown on approximately 20,000ha (representing 10% of the national hectarage), is central to her livelihood. Shabila is the secretary for her group of 22 farmers known as "Mapambano" established by Researcher's at the Oilseed Crops Research Institute - Naliendele in 1994, to conduct Participatory Variety Selection. By 1996 the group had narrowed down the number of elite lines from 25 to 6, among them ICRISAT varieties ICGMS 33 and ICGMS 46. ICGMS 33 was released as Pendo in 1998, and ICGMS 46 as Sawia in 2000.

    Pendo was an instant hit. However, the poor availability of seed became the greatest hindrance to the promotion of the variety. The oilseed crops research program at Naliendele Research Center decided that formation of more farmer-researcher groups could provide the solution. An initial pilot program was launched for Mpeta village, where two more groups "Umoja" and "Upendo" were formed. Researchers trained these groups on quality seed production and linked them to the national seed service network. Seed produced by these groups is now sold to other districts in Tanzania. This year the Mapambano group cultivated 32 hectares of groundnut seed from where they harvested 300 x 90kg bags of good quality seed. The impacts from this achievement are obvious. For example, in 1996 Shabila was the owner of a modest mud grass thatched house. Today she owns a good three-bedroom brick house.

    Shabila posing with husband and son in front of
    their new house(her old mud hut is on the left).

    Other members of the Mapambano group who built houses from groundnut benefits include Mr Hassan Gowele and Mr Yahaya Lazima. Another member of the group, Mr Salum Omari, bought a welding machine with his groundnut profits. The group has purchased a groundnut sheller and an oil expeller, which is used by the group as well as rented out to other members of the community. The enhanced financial position makes it possible for members to take their children through Secondary Schools. The Mapambano group has now become the official seed grower contract group for Naliendele Research Station.

    Shabila receiving a certificate from the Masasi District Commissioner, Hon. Saidi Amanzi, for the best seed pavilion.

    Some of the reasons that contributed to the success of this group include (a) their strategic position (Mpeta is in the middle of the groundnut growing area), (b) cohesiveness of the group due to good leadership from their secretary Shabila, and (c) a common learning field block where farmers and researchers interacted on new technologies.

    For more information contact: e.monyo@cgiar.org or omarimponda@hotmail.com