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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Sustainable Agricultural Systems Laboratory » Research » Publications at this Location » Publication #279049
Title: Cropping history affects nodulation and symbiotic efficiency of distinct hairy vetch genotypes with resident soil rhizobia

Author
item MOTHAPO, NAPE - North Carolina State University
item GROSSMAN, JULIE - North Carolina State University
item Maul, Jude
item SHI, WEI - North Carolina State University
item ISLEIB, THOMAS - North Carolina State University

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2013
Publication Date: 2/20/2013
Citation: Mothapo, N., Grossman, J., Maul, J.E., Shi, W., Isleib, T. 2013. Cropping history affects nodulation and symbiotic efficiency of distinct hairy vetch genotypes with resident soil rhizobia. Plant and Soil. 49:871-879.

Interpretive Summary: Hairy vetch is a nitrogen fixing cover crop used throughout the United States which can provide soil fertility, reduce weed pressure on crop plants and reduce soil erosion. Hairy vetch also provides important ecosystem services such as improved aggregate stability and increased soil carbon sequestration. Many traits found in hairy vetch have proven to be valuable to farmers practicing reduced input and organic farming methods and can contribute to overall farming system sustainability by reducing off farm inputs. Despite being a valuable crop component of sustainable agricultural systems, there has been little effort to improve hairy vetch trait characteristics. Experiments in collaboration with North Carolina State University showed that there are clear differences among hairy vetch cultivars in regards to nodulation and the community of symbiotic Rhizobial bacteria responsible for biological nitrogen fixation. Knowledge of the breadth of genetic diversity among hairy vetch cultivars form the basis for future breeding programs targeting improved traits such as increased biomass production, improved nitrogen fixation capacity and synchronized flowering and development. This information will be used by breeders planning to target specific traits of interest as well as innovative farmers who engage in participatory or self-directed on-farm breeding programs.

Technical Abstract: Presence of compatible rhizobia strains is essential for nodulation and BNF of hairy vetch (Vicia villosa, HV). We evaluated how past HV cultivation affects nodulation and nitrogen fixation across host genotypes. Five groups of HV genotypes were inoculated with soil dilutions from six paired fields, three with 10-yr HV cultivation history (HV+) and three with no history (HV-), and used to trap rhizobia. Nodulation was equated to nodule number and mass, and nitrogen fixation to plant nitrogen. Both HV cultivation history and genotype affected all nitrogen fixation parameters; with the exception of genotype effect on plant biomass. Plants inoculated with HV+ soil dilutions averaged 60% greater nodule number (P<0.005) and 70% (P<0.005) greater nodule mass. Such plants also had greater (P<0.005) plant biomass and plant tissue N than those inoculated with soil dilutions from HV- fields, except one site where no difference in N was found perhaps as a result of rhizobia population mixing between the fields. Plant biomass and tissue N were strongly correlated to nodule mass (r2 = 0.80 and 0.50, respectively), while correlations to nodule number were low (r2 = 0.50 and 0.31, respectively), indicating nodule mass to be a better symbiotic efficiency indicator than number. Although hairy vetch rhizobia occur naturally in soils, past cultivation of HV appears to enhance populations of rhizobia capable of high nodulation and enhanced N fixation.