CONTROL OF BACTERIAL CANKER BY TWO PSEUDOMONADS FLUORESCENT ISOLATES UNDER TOMATO PRODUCTION CONDITIONSN. Amkraz1, H. Boubaker, El H. Boudyach and A. Ait Benaoumar
Our research topic fits into the context of biological control which can be considered as a potential alternative to chemicals when used to control many crops diseases. The effectiveness of two selected strains of fluorescent Pseudomonas studied here (RN69 and RN39e) to protect tomato plants against the invasion of bacterial canker under production conditions was carried out. The results obtained are very promising and they have confirmed that these two isolates significantly reduce the incidence of disease compared to untreated controls. In fact their application alone (RN 39e or RN 69) or as a mixture, reduced the Disease Incidence (DI) to 21.5%, 23.5% and 11.5% respectively. The ability of these bacterial strains to promote tomato's vigor was also tested. Results showed a very interesting PGPR effect especially in the early stages of culture. This improvement is accentuated when using the antagonist mixture. For example, after one month of transplantation, there was a gain of 35.19% and 32.17% over the control for stem height and neck diameter, respectively. The dry weight of both the roots and stems is significantly improved compared to the control for the three types of treatments. There was also a clear increase in the fresh weight of seedlings one month after transplantation. The last step of this work was the in vitro evaluation of the action of some abiotic factors i.e.; temperature, pH and salts on the growth of the two isolates RN39e and RN69. The results showed that these isolates have a wide range of resistance to tested factors. Taking all of the above into account, it can be stated that the two isolates of this study may be of interest both as antagonists and as growth promoters of tomato plants under conditions of saline stress
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