Effect of Azospirillum brasilense and Bacillus subtilis inoculation on durum wheat growth response under four inoculation methods

The growth response of durum wheat (Triticum durum) to inoculation by two rhisospheric rhizobacteria: Azospirillum brasilense and Bacillus subtilis was evaluated by using four ways of inoculation, to determine the best way that gives better results. The two rhizobacteria were inoculated on LB liquid medium. Durum wheat was inoculated twice. For the first inoculation, part of the germinated seeds was directly sown on the ground, and inoculated by bacterial pellet or by medium containing bacterial culture. As for the other part of the germinated seeds, they were firstly soaked for 45 min in a medium containing the bacterial culture, after that, they were sown on ground. For the second inoculation, it was carried out 10 days after sowing, by the same method, except for the seeds soaked in the culture medium, which were inoculated this time by bacterial pellet or by medium containing bacterial culture. After 3 weeks of growth, different plant parameters such as the fresh and dry weight of leaves and roots, the number of leaves, the length of leaves and roots, chlorophyll and carotenoid levels were compared between inoculated and non-inoculated plants and according to different inoculation ways. The results demonstrated that the inoculation of durum wheat with these two strains stimulated the growth of the plant, some parameters gave similar effects between the two bacteria and other parameters gave different effects. Similarly, the type of inoculation influenced the response of the plant to the bacterium; some types gave better results compared to others.