The effects of different nitrogen and phosphorus doses on essentialoil components of some Mentha genotypes

The present study was conducted in Erzurum during the years 2010 and 2011 to determine the effects of different nitrogen and phosphorus doses on essential oil components of spearmint genotypes (Mentha spicata L. and Mentha villoso-nervata Opiz.). Two genotypes of Mentha spicata (genotypes 2 and 6) and one genotype of Mentha villoso-nervata (genotype 4) were tested under three nitrogen and phosphorus doses (0, 50, and 100 kg/ha) in a randomized complete block design with three replications. Essential oil components of the genotypes were determined and subjected to variance analysis. Effects of experimental year and nitrogen and phosphorus doses on investigated traits were found to be significant. Considering the experimental years of 2010 and 2011 and the nitrogen-phosphorus fertilizer doses, 1.8-cineole contents varied respectively between 2.12% and 3.98% (for nitrogen treatments) and between 2.42% and 3.77% (for phosphorus treatments); 4-terpineol contents varied between 1.34% and 2.74% and between 1.30% and 2.73%; pulegone contents between 3.41% and 9.64% and between 4.11% and 8.93%; carvone contents between 21.05% and 33.64% and between 21.77% and 33.54%; piperitone contents between 2.41% and 17.75% and between 2.04% and 17.60%; and finally caryophyllene between 3.98% and 4.93% and between 3.62% and 4.49%, respectively. The greatest 1.8-cineole content was observed in genotype 4 in the first year and in genotype 2 in the second year. Genotype 6 was prominent for 4-terpineol, pulegone, and caryophyllene contents in both years and genotype 4 was prominent for carvone content. The greatest piperitone content was observed in genotype 6 in the first year and in genotype 2 in the second year.