Effects of biological and chemical fertilizers (nitrogen and phosphor) on yeild and oil content of peppermint plant under the climatical conditions of Arak

Peppermint is an important medical plant which contains essential oil that has many usages in different industry. Nitrogen and phosphor are considered to be the most limiting factors of the plant's growth after the factor of water. Chemical fertilizers which are so much used to remove the shortage of these two elements have destructive environmental effects and reduce the quality of crops. Today, using biological fertilizers are considered to be the most suitable strategy to prevent the dangers of chemical fertilizers. This experiment was carried out in the form of factorial based on the Complete Randomized Block Design with four repetitions and two treatments, one of which is Nitrogen fertilizer including three levels of Super Nitro Plus biological fertilizer containing bacteria such as Azospirillum which controls the path of the soil-organism's genetic factors (Basillus sp) and PGPR, plant growth provocative (Pseudomonas flurescens), Nitroxin biological fertilizer containing different doses of Azospirillum bacteria, and Urea chemical fertilizer (300 kg/ha) and also phosphor fertilizer in three levels of Barvar II biological fertilizer containing phosphor releasing bacteria accompanying with Ammonium de phosphate fertilizer (125 kg/ha), Barvar II biological fertilizer and Ammonium de phosphate chemical fertilizer (250 kg/ha) in the agronomical year 1387 in the researching farm of Islamic Azad University of Arak. The results of the mentioned experiment demonstrated that the Super Nitro Plus biological fertilizer and in the second place, Nitroxin cause the significant improvement of the fresh and dry weight of offshoot also amount and efficiency offshoot's essential oil. The combinational treatment of Barvar II and Ammonium de phosphate causes significant improvements of the essential oil efficiency of offshoot. The combinational treatment of Super Nitro Plus and Barvar II causes the significant improvement of offshoot's fresh weight. Also, decreasing the chemical phosphor fertilizer consumption up to fifty percent becomes possible through employing phosphor-releasing bacteria without any significant decline in the growth characteristics and plant essential oil efficiency.