Document Type : Research Paper
1 Faculty member of the Department of Biotechnology and Plant Breeding
2 PhD student of Ferdowsi University of Mashhad, Faculty of Agriculture, Department of Biotechnology and Plant Breeding
3 head of Genetic & Agricultural Biotechnologhy Institute of Tabarestan
4 Faculty member of Ferdowsi University of Mashhad, Faculty of Agriculture, Department of Biotechnology and Plant Breeding
Cyanobacteria are the oldest oxygenic photoautotrophs on earth with a wide ecological distribution. They increase soil productivity by affecting its physicochemical properties. Increasing the application of chemical fertilizers is harmful. Therefore, it has become necessary to look for alternative renewable resources to meet at least a part of the demand for crops. In this study, aimed at increasing the efficiency of cyanobacterial biofertilizer, the effects of nitrogen, phosphorus and potassium elements in the form of urea, superphosphate and potassium chloride fertilizers were evaluated on nitrogen fixation activity measured by gas chromatography, nifH gene expression and the growth of cyanobacterium Aliinistoc sp. In general, the growth and nitrogen fixation activity of the sample decreased as the concentration of nitrogen and phosphorus sources increased. The most effect of nitrogen source was on nitrogenase activity, and at the end of the experimental period compared to the beginning (before treatment), the amount of nitrogenase activity decreased 50 and 100% in the presence of 10 and 100 mg/L urea, respectively. Phosphorus had a significant effect on the growth of the sample, and at the highest concentration of superphosphate (500 mg/L), growth declined about 80%. On the other hand, potassium especially at the lowest concentration (125 mg/L), significantly increased growth by about 20% and doubled nitrogenase activity. In addition, the evaluation of nifH gene expression confirmed the pattern of nitrogenase activity. In general, the results of this study indicate that the dosage of elements used in combination with cyanobacterial biofertilizers should be considered.