Introduction:

Bioproduct’s development to beneficiate economic importance crops such rice, contributes directly to our food sovereignty. The objective of the work was: To obtain and characterize bacterial strains associated with two rice cultivars widely distributed in Cuba, in terms of their potential as Plant Growth Promoting Bacteria.

Methods:

Bacteria associated to the rhizosphere and seeds of INCA LP-5 and INCA LP-7 rice cultivars were isolated and identified by partial 16S rRNA sequencing. The strains were characterized in terms of potentialities as biofertilizers, phytostimulants, biocontrol, and attributes of infection and colonization. The endophytic capacity of a Rhizobium strain was studied in rice seedlings, from inoculation tests and confocal fluorescence microscopy. Inoculation experiments were carried out under controlled, semi-controlled and field conditions.

Results:

We isolated 43 strains; 24 from the rhizosphere and 19 from rice seeds and eight associated bacterial genera were identified: Rhizobium, Pantoea, Pseudomonas, Acinetobacter, Mitsuaria, Enterobacter, Bacillus and Paenibacillus. Some strains solubilized calcium and potassium phosphate, grew in nitrogen-free media, and produced siderophores, indole compounds, hydrolytic enzymes, and formed biofilms. The endophytic capacity of a Rhizobium strain was verified by systemic colonization of rice seedlings. The inoculation of some strains increased the content of nutrients, some biomolecules and rice plant growth. Furthermore, the crop yield enhanced between 30% - 80% with reduction of 40% - 60% of nitrogen fertilization. Conclusions, the research constitutes a contribution to the knowledge of Rhizobium-rice interaction and in the identification, characterization and selection of bacterial strains with potential for the development of bioproducts that positively impact the environment, the economy and the society.

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