اثر سيدروفورهاي ميكروبي توليد شده بوسيله سويه هاي بومي ازتوباكتر كروكوكوم بر جذب عناصر كم مصرف در گندم

Effects of Microbial Siderophores Produced by Native Azotobacter chroococcum Strains on Micronutrients Uptake by Wheat Plant

در اين آزمايش 14 سويه ازتوباكتر كروكوكوم جداسازي شده از مزارع گندم اطراف تبريز از نظر توان توليد سيدروفور در شرايط درون شيشه اي با استفاده از محيط كشت جامد حاوي كروم آزرول-اس مورد ارزيابي قرار گرفتند كه برخي از سويه هاي مورد بررسي از توان توليد سيدروفور نسبتاً بالايي برخوردار بودند. سپس با استفاده از خاك سترون در يك آزمايش گلخانه اي با گياه گندم بهاره رقم فلات در قالب طرح كاملاً تصادفي با 16 تيمار شامل 14 سويه باكتري، شاهد مثبت (با كود نيتروژن و بدون باكتري) و شاهد منفي (بدون كود نيتروژن و بدون باكتري) با چهار تكرار، اثر آنها بر جذب Fe ، Zn، Mn و Cu توسط اين گياه مورد ارزيابي قرار گرفت. نتايج تجزيه آماري و مقايسه ميانگين ها نشان داد كه مايه زني با باكتري بر غلظت و مقدار عناصر Fe، Zn و Cu بخش هوايي و ريشه گياه، مقدار Mn ريشه گياه و همچنين انتقال عناصر Fe، Zn و Cu از ريشه به بخش هوايي اثر معني داري داشت. اثر مايه زني باكتري بر غلظت و مقدار Mn بخش هوايي، غلظت Mn ريشه و انتقال Mn از ريشه به بخش هوايي معني دار نشد. نتايج نشان داد سويه هاي برتري كه در شرايط درون شيشه اي از توان توليد سيدروفور بالايي برخوردار بودند باعث افزايش غلظت و مقدار Fe و همچنين انتقال اين عنصر از ريشه به بخش هوايي گياه گندم شده اند.

In this study, 14 strains of A. chroococcum isolated from wheat grown fields around the city of Tabriz, in northwest of Iran, were assayed for siderophore production using chrome azurol-S agar (CAS-agar) method under in-vitro conditions. Results showed that some strains had relatively higher ability in siderophore production. In a pot culture experiment with sterile soil, wheat plants (Triticum aestivum L.CV. Falat ) were inoculated with 14 bacterial strains. Positive control received nitrogen fertilizer without bacterial inoculation and negative control was left un-inoculated and without N- fertilizer. Totally, 16 treatments with four replications were arranged in completely randomized design. Concentartions and contents of Fe, Cu, Zn and Mn in shoot and root as well as translocations of these elements from root to the shoot were determined at the harvest time. Results showed that the inoculation with Azotobacter had significant effects on concentrations and contents of Fe, Zn and Cu in shoot and root. Translocations of Fe, Zn and Cu from root to the shoot were markedly increased in bacterial treatments compared to the positive and negative controls. Mn concentration and content as well as its translocation from root to the shoot were not significantly affected. In-vitro assessment of siderophore production revealed that the higher siderophore production in bacterial stains was in accordance with higher Fe in plant tissue and its translocation as well.