اثر باکتری‌های ریزوسفر در بیوکنترل بیماری پوسیدگی ریشه و طوقه‌ی گندم ایجاد شده توسط قارچFusarium culmorum

Wheat is one of the most important food products that feeds around 40% of the world's population. Among the limitation factors of wheat production, we can point out the wheat root and crown rot disease caused by Fusarium culmorum as one of this factors. The harmful effects of chemical methods in controlling soil-borne pathogens and on the other hand environmental risks of using chemical compounds have attracted the attention of scientists to the use of antagonistic microorganisms. The bacteria were identified by phenotypic and genotypic methods and It was determined that 19 isolates belonged to Pseudomonas genus and 16 isolates were Bacillus spp. In the following, survey of the antagonistic properties of bacteria in laboratory conditions with on either side bacterial and fungal were performed in PDA. After complete growth of control, it was found 17 isolates of Pseudomonas (P) and 2 isolates of Bacillus (B) were inhibitory against Fusarium culmorum. Respectively, Isolates were P2 (2.5 cm), P3 (2.5 cm), P5 (2.4 cm) P2 (2.4 cm), P4 (2.4 cm), P12 (2.4 cm) and P10 (2.4 cm) had the highest Inhibition hole, and the lowest Inhibition was related to 2 isolates Bacillus with numbers B10 and B14 (1 cm). Due to the fact that the bacteria had antagonistic properties, survey of enzymes of cellulase, amylase, chitinase and protease were done on these bacteria. The results of cellulase test showed that the highest production of this enzyme was due to P2, P3, P9, P13 and P15 isolates, and other antagonistic bacteria didn't produce this enzyme. The result of amylase enzyme test showed that two bacteria Bacillus, B10 and B14 had the highest amount of production, followed by P2, P3, P5, P8, P9 and P13, and this feature was not showed on other bacteria. The protease test showed that the antagonistic bacteria were produced this enzyme, and the most enzymatic production was related to P2, P3, P4, P11, P14 and P15. In chitinase test, enzyme production was performed by P2, P3, P4, P8, B10 and B14 bacteria. The comparison of the results of enzymatic tests with antagonistic test showed that protease enzyme plays an important role in biocontrol effect because all of the antagonistic bacteria in this study had this enzyme and P2 and P3, which were the most successful biocontrol samples, was able to produce all the enzymes that destroyed cell wall of fungal and showed the role of these enzymes in biocontrol.