نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 دانشجوی کارشناسی ارشد گروه علوم خاک، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان ایران.
2 هیات علمی
3 دانشیار گروه مهندسی علوم خاک دانشگاه تهران
4 دانشگاه علوم کشاورزی و منابع طبیعی
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: Over the past few decades, soil salinity has reduced global agricultural production by more than 50%. This problem is considered one of the main barriers to crop productivity in arid and semi-arid regions. Salinity stress affects plant growth by altering osmotic pressure and ionic toxicity, disrupting soil biodiversity. Halotolerant actinobacteria can mitigate abiotic stresses such as salinity and drought and improve soil physical, chemical, and biological properties, leading to higher agricultural crop yields. Plant growth-promoting actinobacteria also increase nutrient availability, improve plant growth, and control plant pathogens. Therefore, this research was conducted with the aim of isolating and screening halotolerant actinobacterial isolates from the rhizosphere of agricultural plants and evaluate their silicate solubilization ability and some other plant growth-promoting mechanisms.
Materials and methods: Plant growth-promoting actinobacteria were isolated and screened from the rhizosphere of agricultural crops corn, tomato, soybean, and sesame. To assess their salinity tolerance, all isolates were evaluated in culture medium with different salinity levels. Actinobacteria isolates with the ability to grow in medium containing 1M NaCl were selected and then the plant growth-promoting properties of the isolates including: the ability to produce indole compounds, solubilize inorganic phosphate, solubilize inorganic silicate, produce siderophores, ammonia, and hydrolytic enzymes including cellulase and protease were measured.
Results: A total of 67 actinobacteria isolates were isolated from the rhizosphere of corn, tomato, soybean, and sesame crops. All isolates were able to grow in a culture medium containing 0.2 M sodium chloride. In a medium with 0.5 M sodium chloride, 80% of the isolates grew. Growth was observed in 32.8% of the isolates in a medium with 1 M sodium chloride, 23.9% in a medium with 1.5 M sodium chloride, and one isolate was able to grow in a medium containing 2 M sodium chloride. All actinobacterial isolates were capable of producing indolic compounds, with isolate GP12 showing the highest production rate. Twenty isolates were able to dissolve inorganic phosphate and GP64 isolate exhibiting the highest dissolution rate with 187.8 mg L-1. Six isolates could dissolve inorganic silicate in a solid environment, and quantitative measurements indicated that isolate GP32 had the highest rate (122.79 mg L-1) of inorganic silicate dissolution. Fourteen isolates were capable of producing siderophores, with isolate GP67 achieving the highest siderophore production in quantitative measurements. Isolates GP20, GP67, GP91 had qualitatively more ammonification ability than other isolates. Regarding the production of hydrolytic enzymes, 11 isolates were able to produce cellulase enzyme, and 3 isolates had the ability to produce protease enzyme.
Conclusion:
In the current study, actinobacterial isolates demonstrated growth in high-salinity sodium chloride culture media and exhibited multiple plant growth-promoting characteristics. These isolates show promise as agents to improve plant growth and crop yield. Confirming their effectiveness and capabilities requires pot and field trials to evaluate their influence on plant development and nutrient absorption.
کلیدواژه‌ها [English]
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