Abstract

In Mali, rice cultivation is faced with declining yields due to insufficient soil nutrients and diseases with yield losses of up to 80%. The use of endophytic bacteria and fungi is a more ecological and effective alternative compared to chemicals. This study aims to select at least one endophytic rice bacterium in combination with mycorrhizal fungi to improve the rice production in Mali and effectively control the growth of Xanthamos oryzae. This selection focused on: (i) the isolation of endophytes and (ii) the identification of PGP traits and their enzymatic productions. Thirty seven (37) endophytic bacteria were successfully isolated from rice roots (10 isolates) and seeds (27 isolates) (Table 1). Among the strains isolated, 24 and 29 isolates showed antibiosis activities, respectively against XOO and XOOC, 24 and 12 isolates showed, respectively chitin and melanin activities, and 20 isolates produced siderophore. All inoculated rice roots with the endophytic bacteria showed a rice growth-promoting ability. In vitro selection made it possible to retain 6 isolates (DK1, DK2, DK3, DK4, REM2 and REM9). An 18.4% increase in grain weight per plant of rice and 17.14% in yield per hectare for the treatments inoculated with DK4. The size of the plants, the number of fertile thalli, the biomass (fresh and dry) were respectively improved by 8.48, 10.1, 11.82 and 18.43% for the treatments inoculated with DK4 followed by REM9. All agronomy parameters measured were significantly increased by bacterial endophytes compared to the controls. These results showed that bacterial endophytes with high PGP activities improve host-plant growth traits and can be used as biofertilizers.

Key words: Bacterial endophytes, rice, biofertilizer, plant growth, Mali.