SO1. Advancing the Productivity Frontier

SO1: Advancing the Productivity Frontier for Grain Legumes

To sustainably and substantively increase grain legume productivity by improving plant adaptation to diverse agroecologies and reducing smallholder farmer vulnerability to climate change, with special consideration for the livelihoods of women.

The global production of grain legumes is inadequate to meet current and projected demands for food for the growing world population. Enhancing grain legume productivity presents certain formidable challenges because the average yields of edible grain legumes in many regions of the world are unacceptably low, frequently less than 25 percent of genetic yield potential (400–800 kg/ha versus 1800–3200 kg/ha). Long-term trends in grain legume productivity do not provide much hope that yields will increase in the near future without the deployment of game-changing technologies or the intensification of production management practices utilizing inputs.

Because smallholder farmers in developing countries are frequently resource-constrained, the purchase of costly inputs, such as fertilizers and pesticides, is not an option. Moreover, farmers must have confidence in the efficacy of the input(s) before pursuing credit to purchase them. High vulnerability to risk, especially when the purpose for growing grain legumes is to provide household food, becomes a major disincentive for resource-poor farmers.

The development of grain legume varieties with increased genetic yield potential is a sustainable strategy that clearly benefits farmers regardless of scale or access to resources. Because grain legumes are self-pollinating and can be used from one generation to another for planting, genetic traits in a new variety conferring higher productivity potential and resistances to abiotic and biotic stresses would benefit farmers over the long term.

The genomics revolution has recently transformed the genetic improvement of crops and made feasible the effective use of biological diversity to improve agricultural systems in new and innovative ways. Sequencing the genome of legume species allows for the identification of quantitative trait loci (QTLs) for specific morphological, biochemical, and physiological traits associated with grain yield and adaptation to stress. With genetic markers for important traits, a breeder can more efficiently and effectively incorporate and combine genes to achieve breeding objectives.

This strategic objective 1 provides a research framework for exploiting new genomics tools (e.g., affordable high-resolution SNP genotyping, high-density gene maps, SNP markers, phenotyping of germplasm collections, etc.) for both Phaseolus vulgaris (common bean) and Vigna unguiculata (cowpea), including markers identified through BeanCAP and TL-1 (CGIAR-GCP), to achieve substantial gains in genetic yield potential that will enable smallholder farmer households to become nutritionally secure while concurrently creating income generation opportunities.

A concomitant strategy must be pursued to reduce the yield gap in legume production, that is, the difference between genetic yield potential and actual grain yields achieved by farmers. The success record of agronomic scientists in reducing the yield gap in grain legumes on smallholder, resource-poor farms in developing countries has been dismal. Formidable challenges to increasing yields through integrated crop management are attributable to high variability in soil fertility and water availability across a production landscape, the inability of farmers to effectively diagnose abiotic, edaphic, and biotic constraints to grain legume productivity, and limited access by farmers to information and productivity-enhancing technologies and inputs. The Legume Innovation Lab will seek to address these constraints to productivity where modern science affords opportunities to provide sustainable and appropriate solutions to smallholder farmers (e.g., the biological control of pests in cowpea).

Two strategic subobjectives are therefore proposed under SO1:

  • SO1.A: To substantively enhance the genetic yield potential of common bean and cowpea by exploiting new research tools afforded by genomics and molecular breeding approaches (MAS), with a focus on improving resistances to economically important abiotic and biotic constraints that limit yield in strategic cropping systems in Africa and Latin America where grain legumes are extensively grown.