Co-Inoculation with <i>Azospirillum brasilense</i> and <i>Bradyrhizobium</i> sp. Enhances Nitrogen Uptake and Yield in Field-Grown Cowpea and Did Not Change N-Fertilizer Recovery
Fernando Shintate Galindo,
Paulo Humberto Pagliari,
Edson Cabral da Silva,
Vinicius Martins Silva,
Guilherme Carlos Fernandes,
Willian Lima Rodrigues,
Elaine Garcia Oliveira Céu,
Bruno Horschut de Lima,
Arshad Jalal,
Takashi Muraoka,
Salatiér Buzetti,
José Lavres,
Marcelo Carvalho Minhoto Teixeira Filho
Affiliations
Fernando Shintate Galindo
Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba 13418-900, Brazil
Paulo Humberto Pagliari
Southwest Research and Outreach Center, Department of Soil, Water, and Climate, University of Minnesota, Lamberton, MN 56152, USA
Edson Cabral da Silva
Goiano Federal Institute, Rio Verde Campus, Rio Verde 75901-970, Brazil
Vinicius Martins Silva
Department of Biology Applied to Agriculture, São Paulo State University, Jaboticabal 14884-900, Brazil
Guilherme Carlos Fernandes
Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira 1585-000, Brazil
Willian Lima Rodrigues
Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira 1585-000, Brazil
Elaine Garcia Oliveira Céu
Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira 1585-000, Brazil
Bruno Horschut de Lima
Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira 1585-000, Brazil
Arshad Jalal
Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira 1585-000, Brazil
Takashi Muraoka
Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba 13418-900, Brazil
Salatiér Buzetti
Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira 1585-000, Brazil
José Lavres
Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba 13418-900, Brazil
Marcelo Carvalho Minhoto Teixeira Filho
Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira 1585-000, Brazil
This study was designed to investigate the effects of Azospirillum brasilense and Bradyrhizobium sp. co-inoculation coupled with N application on soil N levels and N in plants (total N, nitrate N-NO3− and ammonium N-NH4+), photosynthetic pigments, cowpea plant biomass and grain yield. An isotopic technique was employed to evaluate 15N fertilizer recovery and derivation. Field trials involved two inoculations—(i) single Bradyrhizobium sp. and (ii) Bradyrhizobium sp. + A. brasilense co-inoculation—and four N fertilizer rates (0, 20, 40 and 80 kg ha−1). The co-inoculation of Bradyrhizobium sp. + A. brasilense increased cowpea N uptake (an increase from 10 to 14%) and grain yield (an average increase of 8%) compared to the standard inoculation with Bradyrhizobium sp. specifically derived from soil and other sources without affecting 15N fertilizer recovery. There is no need for the supplementation of N via mineral fertilizers when A. brasilense co-inoculation is performed in a cowpea crop. However, even in the case of an NPK basal fertilization, applied N rates should remain below 20 kg N ha−1 when co-inoculation with Bradyrhizobium sp. and A. brasilense is performed.
