INVESTIGADORES
GARRIZ andres
congresos y reuniones científicas
Título:
CHARACTERIZATION OF NITROGEN FIXING BACTERIA IN SOILS FROM ENTRE RIOS IN SYMBIOSIS WITH Lotus Spp FORAGE SPECIES
Autor/es:
MAGUIRE V.; BOUILLY P; JUAN PEDRO EZQUIAGA; ANDRÉS GÁRRIZ; OSCAR A RUIZ
Reunión:
Congreso; Reunion conjunta SAIB-SAMIGE 2020; 2020
Resumen:
Entre Ríos is the second most important province for rice production in Argentina. The most suitable soils for rice cultivationare those belonging to the Vertisol order, characterized by low edaphic phosphorus and nitrogen concentration and a highlydiverse microbial community (Maguire et al APSOIL2020 https://doi.org/10.1016/j.apsoil.2020.103535). In order to isolate,select and identify indigenous microorganisms able to fix nitrogen more efficiently than the commercial strains used for Lotusspp forage species, we grew 100 Lotus spp. ?trap plants? in pots containing Vertisol soil samples collected in rice-pasturerotation systems, the main crop management strategy used in Chajarí (Entre Rios, Argentina). Nitrogen fixing bacteria wereisolated from harvested root nodules, and BOX-PCR analysis were performed in order to discard duplicate strains. From atotal of 32 isolated bacterial strains, 8 were exhaustively tested in L. corniculatus plants for nitrogen fixation efficiency, alongwith the reference strain NZP2213, a commercial inoculant (NITRASOIL®) and control plants irrigated with inorganic N.Under our experimental conditions, the RIZ17 and RIZ35 strains showed a clear tendency to increase stem and root dry weightin inoculated plants. RIZ17, NZP2213, RIZ35, RIZ24 and the commercial strain were the treatments that showed the highestimpact in leaf areas. Plants inoculated with RIZ17, despite showing the highest nodule number, present the lowest mean noduleweight. Infection with RIZ17, RIZ35 and RIZ20 did not lead to differences in total N contents in stems from those found inplants inoculated with the commercial, NZP2213 and control plants. At last, the variable stem dry weight was best explainedby nodule weight (r=0.86) and total nodule area (r=0.73). We conclude that RIZ17 and RIZ35 show valuable potentials for theformulation of inoculants for Lotus spp. After sequencing and analyzing the ribosomal marker gene 16S rRNA, RIZ17 andRIZ35 were taxonomically classified as Mesorhizobium sp. and Variovorax paradoxus, respectively. Moreover, through theN15 isotopic abundance technique, the ability of L. corniculatus to fix nitrogen through its association with native rhizobia wasevaluated, and the amount of N derived from the atmosphere (%Ndfa) was equal to 82.6%. After L. corniculatus ?B factor?determination, a potential 2,5 kg N/ha fixation was estimated in rice pasture rotation in Vertisol soils.