Landraces represent crop varieties that have been grown for centuries, often by traditional farmers. These farmer-selected cultivars can be uniform for seed shape and color, or represent mixtures of different seed types. Similarly, agronomic traits can be uniform or mixtures of different types. Many landraces are locally adapted but can be distributed regionally. Landraces, because of their natural selection under low input production systems and often in challenging environments, are great reservoirs of genetic diversity for many different traits including adaptation to low fertility soils, drought, and other abiotic and biotic stresses.
With this in mind, the FtF ARS Grain Legumes Team, obtained all the dry bean landrace accessions that had been collected from East Africa and conserved at the USDA-ARS, Western Regional Plant Introduction Station in Pullman, WA (250 accessions). A subset of 95 landrace accessions from this group, originally collected from Tanzania, and representative of the large-seeded market classes currently grown there, were first increased for seed in Prosser, WA, and then evaluated in a replicated field trial at Sokoine University of Agriculture in Morogoro, Tanzania. The trial, coordinated by Professor Susan Nchimbi and Eninka Mndolwa (Research Associate), sought to test the accessions for general adaptation for growth under low soil fertility. Yields ranged from 640 to 1650 kg/ha, and some accessions possessed more nodules for biological nitrogen fixation than others (ranging from 4 to 38 nodules). The positive and significant correlation (47%) between grain yield and nodule number observed in this trial supports the hypothesis that accessions with more nodules have potential to yield more in low fertility soils. These data, and observations for disease reaction against fungal (angular leaf spot, rust) and viral (bean common mosaic) pathogens provide a rich baseline dataset to guide future utilization of these landrace accessions in breeding of improved dry bean cultivars for East Africa.
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