Gluconacetobacter diazotrophicus (G.d) is a nitrogen-fixing, endophytic
and non-nodulating bacterium isolated from sugarcane. The aim of this
study was to investigate the effect of different G.d concentrations on
tomato plants grown at very low nitrogen levels to examine its ability to
colonize plant tissues and improve crop yield. Tomato seeds were
inoculated with different doses of G.d (109, 1010, and 1011 CFU/ml) and
grown in the glasshouse under nitrogen deficiency conditions. Estimation
of endophytic bacterial population was performed by bio-PCRs analysis
using specific primers for G.d. Three months after sowing, significant
variations in the phenotypes and biomass production were observed: the
inoculated plants with 1010 and 1011 of G.d-Nfix-3%sucrose showed
increased plant height, root length, nitrogen content, and flower number.
They also exhibited a healthier phenotype and higher fruit production in
comparison to 109 of G.d-Nfix-3%sucrose and non-inoculated control
plants. These results showed that coating tomato seeds with specific
concentrations of G.d-Nfix-3%sucrose (1010 and 1011 CFU/ml) was an
effective enhancer for crop production at low nitrogen levels and proved
the ability of G.d to enhance production of tomato fruits. In conclusion,
this study aimed to develop a natural nitrogen fixing seed coating
technology to provide a sustainable solution to fertilizer overuse and
nitrogen pollution. This technology is environmentally friendly because it
based on a food-grade bacterium (G.d) derived from sugarcane. It aims to
address the need of international market for sustainable agricultural
fertilizers. Moreover, it provides a cost benefit to the farmers via reduced
fertilizer costs and improved crops yields.