Utilization of the Azotobacter and Mycohorrhiza as biofertilizer for improving the growth of (Zea mays) by Using sterile soil

Abstract

This study was conducted to isolate and identify the Azotobacter from soils collected from several local sites in Al–Ramadi city to be used later as biofertilizer instead of chemical fertilizer for the growth of (Zea mays). Eleven isolated of bacterial were isolates and identified as Azotobacter one isolate then selected as a sportier its ability to fix nitrogen. Mycohorrhiza was also isolated from the corn roots and used with and without Azotobacter isolate as a biofertilizer as with corn seeds. Fifty four plastic pots were filled with 10kg soil each. Half of these pots were filled with sterile soil. Ten corn seeds were sown in each pot which thinned into three plants after two weeks from planting. The experiment was setup in a completely randomized design with the following treatments which replicated three times:- 1- Control. 2- Seeds inoculated with Azotobacter. 3- Seeds inoculated with Mycohorrhiza. 4- Seeds inoculated with Azotobacter + Mycohorrhiza. 5- Soil with half of the recommended nitrogen (50% N). 6- Azotobacter + 50% N (Az + 50% N). 7- Mycohorrhiza + 50% N (My + 50% N). 8- Azotobacter + Mycohorrhiza +50% N (Az + My + 50% N). 9- Whole of the recommended nitrogen (100% N). The parameters used in biological experiment were plant tall, leaf area, leaf number and stem diameter. The total content of chlorophyll and carbohydrates were estimated in plant tissues. The percentage of nitrogen and phosphors were also estimated in shoots and roots of the plant and in the soil. The results of this work show that:- 1- Plant height reached 97.3cm. In plant treated with Az + 50% N. The total leaf surface area was higher with (Az) treatment compared with other treatments 18.3 dm2 /plant. 2- Leaf number 14.6 leaf/plant treated with (My) treatment. The average diameter of stem was 1.9 cm/plant on plants treated with Az + 50% N. 3- The average dry weight of the shoot was 21.6 g/shoot with (My) or My + 50% N. The dry weight of the root reached an average of 7.33g/plants. 4- Higher amount of chlorophyll (A) was recorded with treatment (Az) 4.65 mg/g. On the other hand chlorophyll (B) was higher in plant treated with My + 50% N 0.95 mg/g. However, higher amount of total chlorophyll was recorded in plants treated with Az + My + 50% N 5.26 mg/g. 5- Higher amount of carbohydrates were recorded in plants treated with My + Az the amount of carbohydrates were 14.73 g/100g shoot and 14.15 g/100g in the tissues. 6- Using Az + My treatment resulted in higher percentage of Nitrogen 2.773% in the shoot. The percentage of Nitrogen in the root tissues was much higher in plants received Az + My treatment 2.52%. 7- The percentage of phosphorus in the shoot was much higher in plants treated with Az + My 0.85%. However, the percentage of phosphorus in the roots was the same 0.95% irrespective of the treatment or type. 8- The percentage of residual Nitrogen and phosphorus were estimated in the soil. The percentage of Nitrogen was 213 mg/kg Az + My treatment. The percentage of phosphorus was 25.6 mg/kg using Az + My +50%N treatment.