The effect of chemical and biological nitrogen fertilizers on quantitative and qualitative traits of Peppermint (Mentha piperita L.)

Bio-fertilizers in agriculture have great importance and use of these fertilizers in addition to nitrogen-fixing air also makes significant contributions in reducing use of nitrogen chemical fertilizers. Therefore an experiment to investigate the effect of nitrogen chemical fertilizer and Nitroxin bio-fertilizer was conducted factorial randomized complete block design (RCBD) with three replications. Experimental factors were involved nitrogen chemical fertilizer at three levels zero (no fertilizer as control), 100 and 200 kg Urea ha-1, Nitroxin biological fertilizer at two levels of non-inoculated and inoculated with biological fertilizer (4 lit.ha-1) and harvest time three levels of harvested before flowering, coinciding with flowering and after flowering. The results showed that the effect of urea fertilizer, bio-fertilizer, harvest time and the interaction effect of two way and three way of this treatment was significant on fresh and dry matter yield, plant height, percentage and yield of essential oil and harvest index. The maximum dry matter (550 kg), harvest index (72%), oil yield and essential percentage (respectively 20.35 kg.lit-1 and3.7%) was obtained in application of 200 kg Urea ha-1fertilizer with the use of Nitroxin bio-fertilizer in harvest during flowering. Nitroxin biological fertilizer application (4 kg.ha-1) at harvest during flowering caused increase quantitative and qualitative yield of peppermint. Generally the results show that nitroxin bio-fertilizer are positive effects on peppermint through nitrogen fixation and growth hormones produced.