Co-inoculation with diazotrophic bacteria in soybeans associated to urea topdressing

• Main Authors: Glauber Monçon Fipke, Gerusa Massuquini Conceição, Luiz Fernando Teleken Grando, Rodrigo Luiz Ludwig, Ubirajara Russi Nunes, Thomas Newton Martin
• Format: Article
• Language: English
• Published: Universidade Federal de Lavras
• Series: Ciência e Agrotecnologia
• Subjects: Azospirillum spp.; Bradyrhizobium spp.; Glicine max (L.) Merr; nitrogen.
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542016000500522&lng=en&tlng=en

ABSTRACT Increased grain yield can be obtained via an interaction between plants and growth-promoting microorganisms. The Bradyrhizobium spp. are capable of fixing atmospheric nitrogen in soybeans [Glycine max (L.) Merril], and Azospirillum spp. induce the synthesis of phytohormones. The aim of this study was to evaluate inoculation with Bradyrhizobium and co-inoculation with Bradyrhizobium + Azospirillum brasilense in soybeans in combination with the application a topdressing of 0, 75 or 150 kg of N ha-1 of urea during the reproductive stage. Three soybean cultivars (BMX Ativa, TEC 6029 and BMX Potência), were tested in field experiments in Santa Maria, RS, Brazil, during two agricultural years (2013/2014 and 2014/2015) and two sowing times. Morphological, nodulation and yield components were evaluated. Co-inoculation increased the grain yield by 240 kg ha-1 compared with conventional inoculation. When co-inoculated, cultivars BMX Ativa, TEC 6029 and BMX Potência showed increased grain yields of 6, 4 and 12%, respectively. The application of 150 kg ha-1 of N as a topdressing increased the grain yield by 300 kg ha-1 in the co-inoculated cultivars TEC 6029 and BMX Potência, but without a financial return. When inoculated only with Bradyrhizobium, the cultivars did not respond positively to the application of urea.