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Characterization of nodulation capacity with native rhizobia in germplasm of underutilized forage species of Macroptilium (Benth.) Urb.

Juan Marcelo Zabala , Lorena Marinoni , Nicolas Zuber, Laura Fornasero, José Pensiero

Abstract

Context: Great Chaco is a livestock region with several underutilized legume forage genetic resources. Aims: To generate reliable characterization and selection schemes in germplasm of Macroptilium for biological nitrogen fixation with native rhizobia, we carried out a trial to evaluate the germplasm variability for initial growth and nodulation capacity with native soil of subtropical environment. Methods: the trial used seeds of 20 accessions of 5 species of Macroptillum from germplasm banks. Plants were grown - under two conditions, substrate with and without nitrogen added. The variables were analyzed through a nested ANOVA with the factor species, accessions nested within species, nitrogen level and the corresponding interactions. Relationships between variables and accessions were examined using principal component analysis. Key Results: There was variability in the symbiotic response and initial growth, and most of the variance was explained by differences between intraspecific. Nodulation capacity was related with biological nitrogen fixation, since the accessions with higher nodule number and nodule weight showed higher initial growth and higher crude protein content in shoot. Conclusions: In the evaluated germplasm we found variability for nodulation capacity associated with biological nitrogen fixation. In relation to effectiveness, five of twenty accessions evaluated were classified as effective. Implications: our breeding approach could contribute to develop native legume forage cultivars with better symbiosis with native rhizobia, which would reduce implantation costs and reduce the use of chemical nitrogen fertilizers.

CP24290  Accepted 16 January 2025

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