Improving crops

Modernizing the IITA soybean breeding program for enhanced genetic gains

  • October 16, 2020

IITA’s Soybean Improvement Program (ISBP) remains the primary source of improved germplasm for both private and public organizations with over 100 varieties released by partners. The ISBP activities are mainly supported by the USAID (about 75%) and partly by the Soybean Innovation Laboratory and CGIAR Research Program on Grain, Legumes, and Dryland Cereals (GLDC). Increasing the rate of genetic gain through a consistent rate of variety turnover to avoid genetic dilution is the cornerstone of the breeding program.

High yielding soybeans

High yield soybean varieties in the breeding pipeline.

As part of the modernization process, the program focused on:

  • Operationalizing the stage-gate breeding process
  • Refining product profiles and market segments
  • Expanding network testing through the Pan African variety trials, and
  • Upgrading and implementing modern technologies, mechanization, and digitization of data collection and transfer

Operationalizing the stage-gate breeding process

To clearly define the roles, responsibilities, expertise, and criteria of making decisions as well as engage collaborators at various stages of the breeding program, the Stage-Gate approach has been operationalized in the IITA soybean breeding program. The Stage-Gate approach permits advancements, process, and resource allocation based on defined breeding metrics. These metrics allow quantifying genetic gain, which is crucial in measuring the impact of the breeding programs. The stage-gate also allows leverage of germplasm in gene pools and breeding populations to increase and preserve genetic diversity for long-term improvements as well as avoid dilution of genetic gain by managing the product life cycle. (Figure 1)

Refining product profiles, trait prioritization, and market segmentation

The program aims to develop products suited for market needs in alignment with the value chain based on product profiles. Product profiles, trait prioritization, and market segmentation are refined in consultation with public and private sector partners. The four main market segments which the breeding program will focus on include early maturing soybean for the lowland savanna, early maturing soybean for the mid-altitude savanna, medium to late maturing soybean for the lowland savanna, and medium to late maturing soybean for the mid-altitude savanna. A portfolio of deliverables within the market segments included soybean varieties with resistance to the Asian soybean rust (Phakopsora pachyrhizi), large-seeded varieties, tolerance to lodging and shattering. Breeding pipelines are based on the market segments to ensure that varieties developed to meet the specific demands as per the product profiles have also been initiated. On average more than 20,000 lines at different breeding stages are evaluated annually to identify lines that fit within the product profiles determined by the market segments.

Expanding network testing through Pan African Variety Trials

The Pan-African Soybean Variety Trial (PAT) network is an initiative by the Soybean Innovation Lab (SIL), IITA, the Syngenta Foundation for Sustainable Agriculture (SFSA), and the African Agricultural Technology Foundation (AATF). The Pan-African Soybean Variety Trial network fast tracks testing, release, and registration of soybean varieties through a transparent process. Over 21 countries are participating in the PAT and with evaluated lines coming from Australia, Colombia, USA, and both the national and private sector breeding programs in Africa. Figure 3 shows the number of countries and organizations that participated in the PAT during the 2019 season.

Figure 1. The stage-gate variety delivery process by the IITA soybean breeding program. Refining product profiles, trait prioritization, and market segmentation.

Upgrading and implementing modern technologies

Optimization of trial designs and field management practices to reduce error and maximize heritability and genetic gain is an essential aspect of the modernization of the soybean breeding program. With support from the Soybean Innovation Laboratory,

Figure 2. Pan African Variety Trial Network 2019 – countries and institutions.

Table 1. Mean yield (kg/ha) of the best five varieties in the Pan African Variety Trials in Nigeria, 2019 season.

Variety Ibadan Zaria Mean
PANORAMA-27-D 4733 3002 3868
SC-SIGNA 3251 2976 3113
TGX1951-3F (IITA check) 2967 3006 2986
QUARSHE 3055 2422 2739
JENGUMA 2669 2797 2733
Mean 2481.1 1686.2 2083.6
PROB 0.0008 <.0001 <.0001
SE 558.5 138.3 284.2
soybean farmland

Figure 3. Trials planted with a mechanical planter at the IITA station in Lusaka, Zambia.

IITA soybean breeding is one of the first programs to adopt mechanical planting (Fig. 4).  Mechanized planting ensures precise planting depth and seed placement, allowing for uniform germination, hence better experimental data and accuracy for the breeding program. The speed of planting is also significantly increased. One can plant four-row plots of between 3,000-4,000 plots per day. Digitization of data collection and transfer which include the use of the Breeding Management System has also been adopted with training offered to national program partners involved in the PAT.

The future

Although a sustained rate of genetic gain is key to African agricultural transformation, the success of a breeding program is measured not only by variety turnover but also by the performance of the new varieties in farmers’ fields. The ability to track metrics and identify bottlenecks requires a well structured breeding program. In collaboration with Excellence in Breeding (EiB) and the private sector, there is still scope for continuous improvements of CGIAR breeding programs to effectively deliver genetic gains to farmers’ fields in a cost-effective way similar to private sector partners.

 

Authors: Godfree Chigeza, Abush Tesfaye, Christabell Nachilima, McDonald Nundwe and Ulitile Machivete

 

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