Plant-promoting rhizobacteria Methylobacterium komagatae increases crambe yields, root system and plant height

The urgent need to reduce the use of fossil sources, whether agricultural inputs or fuels, and to promote a more sustainable means of production has become an incessant search worldwide. Plant growth-promoting rhizobacteria (PGPR) can be an important alternative once they act in the biogeochemical cycles of nutrients in the soil and in the maintenance of soil and plant health and quality. Crambe abyssinica has been recognized as an important crop for the production of high-quality biodiesel. The identification of specific PGPR are of great importance for the production of sustainable and low-cost biodiesel. The effect of four different PGPR and its mixture, on the growth and yield of Crambe was assessed in a greenhouse setting. Six treatments were used: Azospirillum brasilense (strain Ab-V5), Methylobacterium komagatae (strain ZM), Rhizobium sp. (strain 8.1.2.1), Azomonas sp. (strain 4.3.1.2), a mixture of these four and no inoculation. Plant height and stem diameter, the area of roots, and yield were evaluated. M. komagatae, Azomonas sp. and Rhizobium sp. provided an average of 102% greater root area compared to uninoculated crambe. However, only M. komagatae provided a significant yield increase (108%). The positive responses of a bacterium not previously reported as growth-promoting enables also a series of study possibilities such as the elucidation of the mechanisms of association and testing in other plantas, particularly other Brassicaceae.