The efficiency of Bacillus subtilis and Thuja orientalis leaves extracts as biocontrol agents of damping off in wheat (Triticum aestivum)

Aims: This study was aimed to identify the impact of Bacillus subtilis and alcoholic and aqueous extracts of Thuja orientalis leaves on the mycelium growth of Fusarium solani and Rhizoctonia solani responsible for damping off in wheat plants (Baraka variety).Methodology and results: Four concentrations (10, 15, 20 and 25 mg/mL) of aqueous and alcoholic extracts of T. orientalis and B. subtilis powder were tested for their inhibitory activity against F. solani and R. solani on PDA media.An in vivo experiment was also conducted by soaking wheat seeds in 25 mg/mL aqueous and alcoholic extracts of T. orientalis.On the other hand, B. subtilis was used to contaminate seeds that were planted in soil polluted with the tested fungi to evaluate the disease severity and measure some vitality parameters.The results showed that B. subtilis was effective at inhibiting the growth of F. solani with an inhibition rate of 51.2%.Higher inhibition rates were observed (83.67% and 70.48%) when using 25 and 20 mg/mL of Thuja alcoholic extract, respectively.Greenhouse experiments showed that the alcoholic extract, at a concentration of 25 mg/mL reduced disease severity from 0.39 to 0.2 in soil contaminated with R. solani and from 0.77 to 0.19 by B. subtilis in soil contaminated with F. solani.These treatments of seeds with B. subtilis led to an increase in the growth parameters of wheat seedlings, as the dry weight of the shoot increased from 0.019 g in the control of F. solani to 0.041 g and from 0.027 g to 0.046 g in the control of R. solani.The length and weight of the root system treated with both aqueous and alcoholic extracts against R. solani significantly increased. Conclusion, significance and impact of study:Research findings suggest the possibility of using B. subtilis as well as the alcoholic extract of T. orientalis to treat F. solani, as they were both effective in eliminating the growth of F. solani in laboratory conditions as well as reducing the severity of the disease in the greenhouse experiment.Results showed significant inhibitory activity against R. solani and F. solani; the highest inhibition rate was 83.67% and 64.82%, respectively.The alcoholic extract of T. orientalis was more effective in eliminating the growth of F. solani compared to the aqueous extract.