نوع مقاله : مقاله کامل علمی پژوهشی
نویسنده
گروه گیاهپزشکی، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسنده [English]
Background and objectives: Seedling disease complex is one of the most seroius diseases of cotton in most cotton-gowing areas.The soilborne fungi, Rhizoctonia solani is a prevalent and important pathogen in the incidence of the disease associated with reduced plant vigor. The inoculation of seeds or roots with fluorescent Pseudomonas to increase plant vigour and growth has been a worldwide studied practice. This study, focused on the fluorescent Pseudomonas strains, for inhibition capacity of fungal growth in vitro and their useful for the suppression of R. solani in the cotton rhizosphere.
Materials and methods: To find suitable approach to control of damping-off caused by Rhizoctonia solani, the effects of seed priming with four isolates of Pseudomonas fluorescens on some physiological characteristics of three cotton cultivars (Sahel, Golestan and Varamin) as well as infection rate were investigated. The cotton seeds were coated with P. fluorescens by soaking them in bacterial suspensions of 108 cells/ml bacteria for 15 min, plated in Petri dishes and germinated at 25°C. The effect of soil treatment method with P. fluorescens on plant growth and infection rate was studied in pot experiments using infected soils. The bacterial isolates evaluated for volatile and non-volatile metabolites, sidrophore, hydrogen cyanide and IAA production.
Results: The results show the production of indole acetic acid, sidrophoreand hydrogen cyanide contents were significantly different among bacterial isolates. Analysis of variance also revealed the significant improved of seed germination, root and stem growth and plant dry weight and decrease of disease index by bacteria. The total pheniolic content and proxidase activity also significantly increased in roots after P. fluorescens treatments and the inverse relationship with disease index. The effects of bacterial isolates on studied characteristics were different and significant correlated with IAA and non-volatile metabolites production by bacteria (pearson coefficient 52-82). The effect of bacterial isolates on cotton cutivars were not siginificant.
Conclusion: These results indicate that certain members of the P. fluorescens strains may be useful as an antagonist to R. solani and may facilitate establishment of stands of healthy cotton seedlings. seedling growth improvement and induced resistance against R. solani disease of cotton is possibly the result of the production of the antifungal antibiotic and growth hormones. These results suggest the role of bacteria in germination and. Hence, using of bacteria as a biotechnologic approach be suggested for improve plant to damping-off resistance. These results suggest the role of bacteria in germination and. Hence, using of bacteria as a biotechnologic approach be suggested for improve plant to damping-off resistance.
کلیدواژهها [English]