Nodulation and biological nitrogen fixation of common bean rhizobia from Santa Catarina Plateau soils

Abstract

Curitibanos town is the third regular bean producer (Phaseolus vulgaris L.) in Santa Catarina. However, the regional production decreased due to problems such as the nitrogen fertilizers cost. Farmers do not use seed inoculation because of inoculant’s rhizobia low performance and adaptation to edaphoclimatic conditions. Thus, 36 rhizobia were isolated, characterized, and evaluated by in vitro indole acetic acid (IAA) production and phosphate solubilization, as auxiliary tools to the rhizobia selection. Ninety-two percent of the isolates produced IAA and 64% solubilized calcium phosphate. The isolates selected for field trials during two consecutive years were RBZ14 and RBZ15. RBZ14 produced an IAA higher amount than strain CIAT899 (recommended for inoculants) and RBZ15 formed a lower amount. For phosphate solubilization, all showed similar performance. In the first year, the isolates increased leaf N contents in the TAA Dama cultivar. RBZ15 increased the productivity. In the second year, in the IPR Tuiuiú cultivar, the isolates also increased leaf N contents, and there was no difference at productivity but increments of 120 and 205 kg.ha-1 with RBZ14 and RBZ15 inoculations, respectively. Therefore, it suggested their potential for BNF in different genotypes and that evaluated mechanisms may help to the selection of a more efficient rhizobia.