The ability of endophytic bacteria to inhibit the growth of crown and root rot fungal-like Phytophthora nicotianae and Phytophthora citrophthora on Bakraii rootstock (Citrus sp.)

Endophytic bacteria are one of the most powerful tools in bio-controlling plant pathogens and protecting plants from damage. The evaluation of inhibitory effect of endophytic bacteria isolated from Mandarin orchards in Hormozgan province against crown and root rot caused by fungal-like Phytophthora nicotianae and Phytophthora citrophthora in laboratory (completely randomized design) and greenhouse (factorial experiment in completely randomized design) was performed with three replications. Also, the biomass parameter of fresh and dry weight of the stem, root and their corresponding lengths were investigated. In this experiment, 17 isolates of endophytic bacteria were identified using 16S rDNA gene. In the laboratory experiment was found that out of 17 endophytic bacteria, 3 isolates had significant inhibitory effect at the 5 percentage probability level; So that in the greenhouse conditions they reduced the disease severity of P. nicotianae and P. citrophthora isolates by 75.5 percentage compared to the control. The sequence of these three isolates was 99 percentage similar to the sequence of Paracrauroccus sp. , Kytococcus schroeteri and Psychrobacillus psychrodurance species. In the greenhouse experiment, the comparison of the means showed that the fresh weight of stem, root and stem length treated with endophytic bacteria increased compared to the control. In general, the endophytic bacteria Paracrauroccus sp. ,Kytococcus schroeteri and Psychrobacillus psychrodurance separately and in combination can be suggested as an effective tool for biological control of the cause of crown and root rot at the Bakraii rootstock.