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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCING BIOLOGICAL NITROGEN FIXATION (BNF) OF LEGUMINOUS CROPS GROWN ON DEGRADED SOILS IN UGANDA, RWANDA, AND TANZANIA
2012 Annual Report


1a.Objectives (from AD-416):
Characterize inheritance of biological nitrogen fixation in dry beans and develop germplasm with improved biological nitrogen fixation.


1b.Approach (from AD-416):
Optimze biological nitrogen fixation in dry beans through genetics and plant breeding. Identify lines with high BNF and cross with lines with low BNF to devlop breeding populations. Evaluate breeding and mapping populations for BNF response and populate with markers for QTL analysis.


3.Progress Report:

TThis is the final Report for project 5354-21220-016-00D terminated in September 2012. This three year project evaluated select bean germplasm for biological nitrogen fixation (BNF) with Rhizobium inoculant and without. The first two years (2010 and 2011) of field studies in Washington State showed that inoculant had a consistent negative 5% reduction on yield. This result was caused by competition between the native and added rhizobium strains. A few lines performed well under low N and were used in crosses with lines which had poor performance to generate segregating populations for investigating inheritance of enhanced BNF. The investigations in 2012 dropped inoculant as a treatment and added other stresses. Three experiments were planted in Spring 2012. All three experiments were planted with lines from the Andean Diversity Panel for Association Mapping of traits affecting abiotic stresses induced by low fertility and drought. The drought study consists of 584 plots, the low fertility study consists of 375 plots, and a study looking at biological nitrogen fixation consists of 1280 plots. Stand and flowering date has been recorded and tissue samples for determining biomass and nitrogen concentration have been collected. Partial single-nucleotide polymorphism (SNP) analysis has been completed for 272 of the 392 lines in the diversity panel. Under sub-objective 1B of the related in-house project, "Develop dry bean germplasm with enhanced disease and/or abiotic stress resistance using MAS in combination with traditional breeding approaches", significant progress was made in identifying lines with general resistance to abiotic stresses. The overall impact of the accomplishments is that breeders have a better understanding of which lines to use for increasing BNF in their breeding programs and that farmers should run test strips to confirm that rhizobium inoculants are improving performance.


Last Modified: 7/28/2014
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