N2-Fixation, nodule efficiency and biomass accumulation after two years in three Chilean legume trees and Tagasaste Chamaecytisus proliferus subsp. palmensis |
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Authors: | Carlos Ovalle Luis Longeri James Aronson Alfonzo Herrera Julia Avendaño |
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Institution: | (1) Instituto de Investigaciones Agropecuarias (INIA), Quilamapu Experimental Station, Casilla 426, Chillán, Chile;(2) Laboratory of Soil Science, University of concepción, Chillán, Chile;(3) CNRS/CEFE, B.P. 5051, 34033 Montpellier, France;(4) Laboratory of Rhizobiology, University of Concepción, Chillán, Chile;(5) Cauquenes Experimental Substation, INIA, Cauquenes, Chile |
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Abstract: | Initial results of a long-term field experiment are presented for the above and below-ground biomass accumulation after two years, as well as root nodulation, nodule efficiency (g N fixed/g nodules) and biological N2 fixation (using the 15N isotope dilution method) of four N2-fixing tree species (NFTs) grown in the subhumid mediterranean-climate zone of central Chile. Two non-legume tree species, Fraxinus excelsior and Schinus polygamus, were used as reference plants for the isotope dilution calculations.Over two years, Tagasaste (Chamaecytisus proliferus subsp. palmensis, a Papilionoideae from the Canary Islands), produced 10 to 20 times more biomass than the other three NFTS (Acacia caven, Prosopis alba and P. chilensis); all Mimosoideae native to Chile, and nodulation and nitrogen fixed were an order of magnitude higher as well. At the end of the second year, the percentage of N derived from N2 fixation (%Ndfa) in Tagasate averaged 85.6, equivalent to ca. 49.1 g N fixed per tree. For all four NFTs, however, %Ndfa, nodule efficiency, and total N accumulation varied from one year to the next; caution is thus required in interpreting or predicting NFT performance over the long term, even if Tagasaste can already be considered a highly promising NFT for central Chile. |
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Keywords: | Acacia caven agroforestry Chamaecytisus proliferus subsp palmensis isotope dilution 15N nitrogen fixation nodule efficiency Prosopis |
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