Improving sugar beet (Beta vulgaris L.) productivity by inoculation with Gluconacetobacter spp.

Abstract

Gluconacetobacter diazotrophicus is nitrogen fixing endophyte that associates with sugar cane. Fourteen strains of Gluconacetobacter spp., including Gluconacetobacter diazotrophicus, were tested for capability of fixing nitrogen in sugar beet at 1 mM and 10 mM NO[subscript 3][superscript -]. Inoculation at different growth stages with different bacteria concentrations was assessed in sugar beets provided 5 mM NO[subscript 3][superscript -] to evaluate its impact on infection level and capacity of nitrogen fixation. A 16S rRNA based PCR technique was applied for identification of isolated strains. GUS labeled strains were also used to investigate the possible sites that the bacteria infect the host plant. Results showed that certain strains improved plant growth significantly. A greater biomass increase and higher nitrogen fixation was found at lower nitrogen treatments. Utilization of GUS-labelled strains of Gluconacetobacter diazotrophicus indicated that root tips, root hairs and the intersection of lateral roots were possible sites of infection by the bacterium.