Evaluation of Quantitative and Qualitative Yiled of Peppermint under Amino Acids, Chemical and Organic Fertilizers

Peppermint is a medicinal plant belong to the Lamiaceae familly which is used in various pharmaceutical, cosmetic and food industries. This research was conducted as a factorial based on randomized complete block design with three replications to evalueate the effect of amino acid application on quantitative and qualitative yield of peppermint under chemichal and organic fertilizers at the research farm of Plant Production and Genetics Department, Faculty of Agriculture, University of Maragheh, Iran in 2017. Treatments were included: I- control, II- chemichal fertilizer, III- vermicompost, and IV- farmyrad manure as first factor and amino acids application as second factor were included application in one stage (before flowering), application in two stages (before flowering and flowering stage) and control. Results showed that the highest plant height, flowering stems number, auxiliary stems number and leaf number were obtained from amino acids application in two stages. The highest dry matter yield of both harvest were obtained by chemical fertilizer application without significant differences with vermicompost application. The highest essential oil yield at the first harvest were obtained by all of the three fertilizers (chemical, vermicompost and farmyard) application and the highest essential oil yield at second harvest were obtained by chemical and vermicompost application. The highest essential oil percentage at first harvest was obtained by foliar application of amino acids at two stages + farmyard manure application (2.91%) and foliar application in two stages + vermicompost application (2.77%). In general, the results showed that the application of organic manures especially vermicompost, like chemical fertilizer are effective in increasing the morphological traits and yield of peppermint. Therefore, considering the incomptable effects of chemical fertilizers on environment, the use of organic fertilizers such as vermicompost and amino acids in sustainable agriculture sustems is recommended.